View source for Chemistry:Vinyl iodide functional group

[[File:Vinyl_iodide_general_structure.png|thumb|168x168px|General structure of vinyl iodides]]
In [[Chemistry:Organic chemistry|organic chemistry]], a '''vinyl iodide''' (also known as an '''iodoalkene''') [[Chemistry:Functional group|functional group]] is an [[Chemistry:Alkene|alkene]] with one or more [[Chemistry:Iodide|iodide]] substituents. Vinyl iodides are versatile molecules that serve as important building blocks and precursors in organic synthesis. They are commonly used in carbon-carbon forming reactions in transition-metal catalyzed cross-coupling reactions, such as [[Chemistry:Stille reaction|Stille reaction]], [[Chemistry:Heck reaction|Heck reaction]], [[Chemistry:Sonogashira coupling|Sonogashira coupling]], and Suzuki coupling.<ref>{{Cite journal |last=Xie |first=Meihua |last2=Wang |first2=Jialiang |last3=Zhang |first3=Wei |last4=Wang |first4=Shaowu |date=2009-06-15 |title=Regio- and stereospecific synthesis of vinyl halides via carbozincation of acetylenic sulfones followed by halogenation |url=https://www.sciencedirect.com/science/article/pii/S0022328X09001806 |journal=Journal of Organometallic Chemistry |volume=694 |issue=14 |pages=2258–2262 |doi=10.1016/j.jorganchem.2009.03.006 |issn=0022-328X}}</ref> Synthesis of well-defined geometry or complexity vinyl iodide is important in stereoselective synthesis of natural products and drugs.

== Properties ==

Vinyl iodides are generally stable under nucleophilic conditions. In S<sub>N</sub>2 reactions, back-attack is difficult because of steric clash of R groups on carbon adjacent to electrophilic center (see figure 1a).<ref name="books.google">{{Cite book |last=Klein |first=David R. |url=https://books.google.com/books?id=SsX9pbarkQkC |title=Organic Chemistry |date=2011-08-24 |publisher=Wiley |isbn=978-1-118-13750-5 |language=en}}</ref> In addition, the lone pair on iodide donates into the ╥* of the alkene, which reduces electrophilic character on the carbon as a result of decreased positive charge. Also, this [[Chemistry:Stereoelectronic effect|stereoelectronic effect]] strengthens the C-I bond, thus making removal of the iodide difficult (see figure 1b).<ref>{{Cite book |last=MEHTA |first=BHUPINDER |url=https://books.google.com/books?id=QV6cwXA9XkEC |title=ORGANIC CHEMISTRY |last2=MEHTA |first2=MANJU |date=2005-01-01 |publisher=PHI Learning |isbn=978-81-203-2441-1 |language=en}}</ref> In S<sub>N</sub>1 case, dissociation is difficult because of the strengthened C-I bond and loss of the iodide will generate an unstable [[Chemistry:Carbocation|carbocation]](see figure 1c)<ref name="books.google" />

[[File:Properties of vinyl iodide.jpg|center|500px|thumb|'''Figure 1.''']]

In cross-coupling reactions, typically vinyl iodides react faster and under more mild conditions than vinyl chloride and vinyl bromide. The order of reactivity is based on the strength of carbon-halogen bond. C-I bond is the weakest of the halogens, the bond dissociation energies of C-I is 57.6kcal/mol, while fluoride, chloride and bromide are 115, 83.7, 72.1 kcal/mol respectively.<ref>{{Cite journal |last=Blanksby |first=Stephen J. |last2=Ellison |first2=G. Barney |date=2003-04-01 |title=Bond Dissociation Energies of Organic Molecules |url=https://pubs.acs.org/doi/10.1021/ar020230d |journal=Accounts of Chemical Research |language=en |volume=36 |issue=4 |pages=255–263 |doi=10.1021/ar020230d |issn=0001-4842}}</ref> As a result of having weaker bond, vinyl iodide does not polymerize as easily as its vinyl halide counterparts, but rather decompose and release [[Chemistry:Iodide|iodide]].<ref>{{Cite journal |last=Herman |first=Jan A. |last2=Roberge |first2=Pierre |date=December 1962 |title=X‐ray induced polymerization of vinyl iodide in solution |url=https://onlinelibrary.wiley.com/doi/10.1002/pol.1962.1206217444 |journal=Journal of Polymer Science |language=en |volume=62 |issue=174 |doi=10.1002/pol.1962.1206217444 |issn=0022-3832}}</ref>
It is generally believed that vinyl iodide cannot survive common [[Chemistry:Redox|reduction]] conditions, which reduces the vinyl iodide to an olefin or unsaturated [[Chemistry:Alkane|alkane]].<ref>{{Cite journal |last=Zhang |first=Xing |last2=Liu |first2=Jun |last3=Sun |first3=Xue |last4=Du |first4=Yuguo |date=2013-02-04 |title=An efficient cis-reduction of alkyne to alkene in the presence of a vinyl iodide: stereoselective synthesis of the C22–C31 fragment of leiodolide A |url=https://www.sciencedirect.com/science/article/pii/S0040402012018273 |journal=Tetrahedron |volume=69 |issue=5 |pages=1553–1558 |doi=10.1016/j.tet.2012.12.008 |issn=0040-4020}}</ref> However, there is evidence in literature, in which a [[Chemistry:Propargyl alcohol|propargyl alcohol]]'s [[Chemistry:Alkyne|alkyne]] was reduced in presence of a vinyl iodide using hydrogen over Pd/CaCO<sub>3</sub> or [[Chemistry:Crabtree's catalyst|Crabtree's catalyst]].<ref>{{Cite journal |last=Denton |first=Richard W. |last2=Parker |first2=Kathlyn A. |date=2009-07-02 |title=Functional Group Compatibility. Propargyl Alcohol Reduction in the Presence of a Vinyl Iodide |url=https://pubs.acs.org/doi/10.1021/ol900927a |journal=Organic Letters |language=en |volume=11 |issue=13 |pages=2722–2723 |doi=10.1021/ol900927a |issn=1523-7060 |pmc=2726658 |pmid=19476372}}</ref>
[[File:Figure 3 Parker group work.jpg|center|Parker's group reduction methods]]

== Other applications ==

[[File:Scheme 1..jpg|thumb|350px|'''Scheme 1.''' Magnesium-halogen exchange]]
Besides using vinyl iodides as useful substrates in transition metal cross-[[Chemistry:Coupling reaction|coupling reaction]], they can also undergo [[Chemistry:Elimination reaction|elimination]] with a strong base to give corresponding [[Chemistry:Alkyne|alkyne]], and they can be converted to suitable vinyl [[Chemistry:Grignard reagents|Grignard reagents]]. Vinyl iodides are converted to [[Chemistry:Grignard reagents|Grignard reagents]] by magnesium-halogen exchange (see Scheme 1a).<ref name="Rottlander, M. 1999">{{Cite journal |last=Rottländer |first=Mario |last2=Boymond |first2=Laure |last3=Cahiez |first3=Gérard |last4=Knochel |first4=Paul |date=1999-02-01 |title=Stereoselective Preparation of Functionalized Alkenylmagnesium Reagents via an Iodine−Magnesium Exchange Reaction |url=https://pubs.acs.org/doi/10.1021/jo981941l |journal=The Journal of Organic Chemistry |language=en |volume=64 |issue=4 |pages=1080–1081 |doi=10.1021/jo981941l |issn=0022-3263}}</ref> The scope of this synthetic method is limited since it requires higher temperatures and longer reaction time, which affects functional group tolerance. However, vinyl iodide with electron withdrawing group can enhance rate of exchange(see Scheme 1b).<ref name="Rottlander, M. 1999" /> Also addition of [[Chemistry:Lithium chloride|lithium chloride]] helps enhance magnesium-halogen exchange (see Scheme 1c). It is predicted lithium chloride breaks up aggregates in organomagnesium reagents.<ref>{{Cite journal |last=Ren |first=Hongjun |last2=Krasovskiy |first2=Arkady |last3=Knochel |first3=Paul |date=2004-11-01 |title=Stereoselective Preparation of Functionalized Acyclic Alkenylmagnesium Reagents Using i- PrMgCl·LiCl |url=https://pubs.acs.org/doi/10.1021/ol048363h |journal=Organic Letters |language=en |volume=6 |issue=23 |pages=4215–4217 |doi=10.1021/ol048363h |issn=1523-7060}}</ref>

== Methods of synthesis ==

[[File:Stereo-regio isomers.jpg|thumb|[[Social:Nomenclature|Nomenclature]]]]
Vinyl iodides are synthesized by methods such as iodination and [[Chemistry:Substitution reaction|substitution reaction]]. Vinyl iodides with well-defined geometry (regiochemistry and [[Chemistry:Stereochemistry|stereochemistry]]) are important in synthesis since many natural products and drugs that have specific structure and dimension. Example of regiochemistry is whether the iodide is positioned in either alpha or beta position on the olefin. [[Chemistry:Stereochemistry|Stereochemistry]] such as E-Z notation or cis-trans alkene geometry is important since some transition metal cross-coupling reactions, such as the Suzuki coupling, can retain olefin geometry. In synthesis, it is useful to introduce vinyl iodide at various positions to be set up for a coupling reaction at the next synthetic step. Below are various means and methods in introducing and synthesizing vinyl iodides.

=== Synthesis from alkynes ===

The common and simplest approach to make vinyl iodide is addition of one equivalent [[Chemistry:Hydrogen iodide|HI]] to [[Chemistry:Alkyne|alkyne]]. This generally makes 2-iodo-1-alkenes or α-vinyl iodide by [[Markovnikov's rule]]. However, this reaction does not happen at good rates or very high stereoselectively.<ref>{{Cite journal |last=Kropp |first=Paul J. |last2=Crawford |first2=Scott D. |date=June 1994 |title=Surface-Mediated Reactions. 4. Hydrohalogenation of Alkynes |url=https://pubs.acs.org/doi/abs/10.1021/jo00090a031 |journal=The Journal of Organic Chemistry |language=en |volume=59 |issue=11 |pages=3102–3112 |doi=10.1021/jo00090a031 |issn=0022-3263}}</ref> As a result, most synthetic methods often involve a [[Chemistry:Hydrometalation|hydrometalation]] step before addition of I+ source.

==== α-vinyl iodides ====

Introducing an α-vinyl iodide from a terminal position of an alkyne is a difficult step. in addition, the vinyl metal intermediate can be mildly nucleophilic, for example vinyl aluminum, can form C-C bonds under catalytic conditions. However, Hoveyda group have demonstrated using nickel-based catalyst (Ni(dppp)Cl<sub>2</sub>), DIBAL-H with [[Chemistry:N-Iodosuccinimide|''N''-iodosuccinimide]] (NIS), selectively favor α-vinyl iodide with little to no byproducts.<ref>{{Cite journal |last=Gao |first=Fang |last2=Hoveyda |first2=Amir H. |date=2010-08-18 |title=α-Selective Ni-Catalyzed Hydroalumination of Aryl- and Alkyl-Substituted Terminal Alkynes: Practical Syntheses of Internal Vinyl Aluminums, Halides, or Boronates |url=https://pubs.acs.org/doi/10.1021/ja104896b |journal=Journal of the American Chemical Society |language=en |volume=132 |issue=32 |pages=10961–10963 |doi=10.1021/ja104896b |issn=0002-7863 |pmc=2921967 |pmid=20698643}}</ref> Also they observed reverse selectivity for β with Ni(PPh<sub>3</sub>)<sub>2</sub>Cl<sub>2</sub> in their hydroalumination reactions under same conditions with little or no byproducts. The advantage of this method is that is inexpensive (and commercially available), scalable and one-pot reaction.
[[File:Figure5 hydroalumination.jpg|center|Hoveyda'group hydroalumination method]]
Another method doesn't involve [[Chemistry:Hydrometalation|hydrometalation]] but hydroiodation with I<sub>2</sub>/hydrophosphine binary system, which was developed by Ogawa's group.<ref>{{Cite journal |last=Kawaguchi |first=Shin-ichi |last2=Ogawa |first2=Akiya |date=2010-05-07 |title=Highly Selective Hydroiodation of Alkynes Using an Iodine−Hydrophosphine Binary System |url=https://pubs.acs.org/doi/10.1021/ol1005246 |journal=Organic Letters |language=en |volume=12 |issue=9 |pages=1893–1895 |doi=10.1021/ol1005246 |issn=1523-7060}}</ref>
[[File:Hydroiodation with I2 and hydrophosphine.jpg|center|Ogawa's group Hydroiodation method with I<sub>2</sub>/hydrophosphine]]
The hydroiodation proceeds by Markovnikov-type adduct, no reaction is observed without addition of hydrophoshine. In a plausible mechanism proposed by Ogawa's group, the hydrophosphine reacts with HI to form an intermediate complex that coordinate HI to do Markovnikov hydroiodation on the alkene. The advantage of this system is the conditions are mild, can tolerate wide range of functional groups.
[[File:Mechanism Proposed by Ogawa's group.jpg|center|Mechanism Proposed by Ogawa's group]]

==== β-vinyl iodides ====

They are generally more methods in making β-vinyl iodides versus α-vinyl iodides using [[Chemistry:Hydrometalation|hydrometalation]] (with aluminum with DIBAL-H (hydroalumination), with boron ([[Chemistry:Hydroboration|hydroboration]]), with HZrCp<sub>2</sub>Cl (hydrozirconation)).<ref name="Chong, J. 2012, pages 654-658">{{Cite journal |last=Darwish |first=Alla |last2=Chong |first2=J. Michael |date=2012-01-14 |title=Synthesis of E-vinyl iodides via Pd-catalyzed hydrostannation of terminal alkynes |url=https://www.sciencedirect.com/science/article/pii/S0040402011016863 |journal=Tetrahedron |volume=68 |issue=2 |pages=654–658 |doi=10.1016/j.tet.2011.10.104 |issn=0040-4020}}</ref> However, [[Chemistry:Hydrometalation|hydrometalation]] with alkyne with various functional groups often react poorly with side products. The Chong groups have demonstrated using hydrostannation, using Bu<sub>3</sub>SnH with palladium catalyst with high E stereoselectivity.<ref name="Chong, J. 2012, pages 654-658" /> They observed using sterically bulky ligands gave higher regioselectivity for β-vinyl iodide. The advantage of this technique is this technique can tolerate a wide range of functional groups.
[[File:Chong's group hydrostannation method.jpg|center|Chong's group hydrostannation method]]
Z selective β-vinyl iodides are slightly more difficult to introduce than E-β-vinyl iodides, often requiring more than one step. Hydroalumination and [[Chemistry:Hydroboration|hydroboration]] usually proceed by syn fashion, therefore selectively favors E geometry. The Oshima group have demonstrated using hydroindation with HInCl selectively favors Z geometry.<ref>{{Cite journal |last=Takami |first=Kazuaki |last2=Mikami |first2=Satoshi |last3=Yorimitsu |first3=Hideki |last4=Shinokubo |first4=Hiroshi |last5=Oshima |first5=Koichiro |date=2003-08-01 |title=Triethylborane-Mediated Hydrogallation and Hydroindation: Novel Access to Organogalliums and Organoindiums |url=https://pubs.acs.org/doi/10.1021/jo0344790 |journal=The Journal of Organic Chemistry |language=en |volume=68 |issue=17 |pages=6627–6631 |doi=10.1021/jo0344790 |issn=0022-3263}}Takami, Kazuaki, et al. "Triethylborane-mediated hydrogallation and hydroindation: Novel access to organogalliums and organoindiums." The Journal of Organic Chemistry 68.17 (2003): 6627-6631.</ref> They suggested that the reaction proceeds by a radical mechanism. They predict that HInCl adds to alkyne by radical addition in a Z geometry. It does not isomerized to E geometry because of low reactivity of radical InCl<sub>2</sub> with intermediate complex (no second addition). If second addition occurs then isomerization will occur through diindium intermediate. They confirm a radical mechanism in a mechanistic study with alkyne and alkene cyclization.
[[File:Oshima's group hydroindation method.jpg|center|Oshima's group hydroindation method]]

=== Substitution ===

'''Substitution''' is perhaps most useful method in introducing vinyl iodide into the molecule. Halogen-exchange can be useful since vinyl iodides are more reactivity than other vinyl halides. Buchwald group demonstrates a halogen-exchange from vinyl bromide to vinyl iodide with copper catalyst under mild conditions.<ref>{{Cite journal |last=Klapars |first=Artis |last2=Buchwald |first2=Stephen L. |date=2002-12-01 |title=Copper-Catalyzed Halogen Exchange in Aryl Halides: An Aromatic Finkelstein Reaction |url=https://pubs.acs.org/doi/10.1021/ja028865v |journal=Journal of the American Chemical Society |language=en |volume=124 |issue=50 |pages=14844–14845 |doi=10.1021/ja028865v |issn=0002-7863}}</ref> It is possible that this method can tolerate various functional groups since these conditions were tested [[Chemistry:Aryl halide|aryl halide]]s initially. The scope of this exchange for regiochemistry and [[Chemistry:Stereochemistry|stereochemistry]] is currently unexplored.
[[File:Buchwald's group halogen exchange method.jpg|center|Buchwald's group halogen exchange method]]
Halogen-exchange can also be done with zirconium derivatives that retain olefin’s geometry<ref name="Liard, Annie 2000">{{Cite journal |last=Liard |first=Annie |last2=Marek |first2=Ilan |date=2000-10-01 |title=Stereoselective Preparation of E Vinyl Zirconium Derivatives from E or Z Enol Ethers |url=https://pubs.acs.org/doi/10.1021/jo005561n |journal=The Journal of Organic Chemistry |language=en |volume=65 |issue=21 |pages=7218–7220 |doi=10.1021/jo005561n |issn=0022-3263}}</ref>
[[File:Marek's group Halogen exchange method.jpg|center|Marek's group Halogen exchange method]]
The Marek group have further investigated using zirconium catalyst on E or Z [[Chemistry:Enol ether|vinyl ether]]s, which selective for E-vinyl ethers.<ref name="Liard, Annie 2000" /> The zirconium's oxophilic nature allows elimination alkoxy group at the β position to form intermediate vinyl zirconium complex. The E geometry selectivity is not cause by sterics but rather the reaction itself is not concerted. In a mechanistic study, they observed [[Chemistry:Isomerization|isomerization]], which suggest E geometry product is more favored than Z geometry. The difference of results between halogen exchange and E-vinyl ether reaction is that only when there is a presence of an [[Chemistry:Oxonium ion|oxonium]] intermediate, is [[Chemistry:Isomerization|isomerization]] observed.
[[File:Marek's group zirconium vinyl iodide synthesis from vinyl ether.jpg|center|Marek's group zirconium vinyl iodide synthesis from vinyl ether]]
[[File:Scheme 2 vinyl borate to viny iodide.jpg|thumb|400px|'''Scheme 2.''']]
An interesting substitution reaction is vinyl boronic acid to vinyl iodide done by Brown's group.<ref>{{Cite journal |last=Brown |first=Herbert C. |last2=Hamaoka |first2=Tsutomu |last3=Ravindran |first3=N. |date=1973-10-23 |title=ChemInform Abstract: REACTION OF ALKENYLBORONIC ACIDS WITH IODINE UNDER THE INFLUENCE OF BASE, A SIMPLE PROCEDURE FOR THE STEREOSPECIFIC CONVERSION OF TERMINAL ALKYNES INTO TRANS‐1‐ALKENYL IODIDES VIA HYDROBORATION |url=https://onlinelibrary.wiley.com/doi/10.1002/chin.197343207 |journal=Chemischer Informationsdienst |language=en |volume=4 |issue=43 |doi=10.1002/chin.197343207 |issn=0009-2975}}</ref> Depending on order of addition of iodide or base, vinyl [[Physics:Borate|borate]] can yield different stereoisomers of vinyl iodide (see scheme 2a). The Whiting group, however, noticed that Brown's method was not applicable to more sterically hindered boronic esters (no reaction).<ref>{{Cite journal |last=Stewart |first=Sarah K |last2=Whiting |first2=Andrew |date=1995-05-29 |title=Stereoselective synthesis of vinyl iodides from vinylboronate pinacol esters using ICI |url=https://www.sciencedirect.com/science/article/pii/004040399500644R |journal=Tetrahedron Letters |volume=36 |issue=22 |pages=3929–3932 |doi=10.1016/0040-4039(95)00644-R |issn=0040-4039}}</ref> They proposed that the iodide source was not electropositive enough. So they decided to use ICl which is more polar than I<sub>2</sub>, in which, they observed similar results (see scheme 2b).

Radical substitution of carboxylic acid to iodide is demonstrated by a modified [[Chemistry:Hunsdiecker reaction|Hunsdiecker reaction]].<ref>{{Cite journal |last=Das |first=Jaya Prakash |last2=Roy |first2=Sujit |date=2002-11-01 |title=Catalytic Hunsdiecker Reaction of α,β-Unsaturated Carboxylic Acids: How Efficient Is the Catalyst? |url=https://pubs.acs.org/doi/10.1021/jo025868h |journal=The Journal of Organic Chemistry |language=en |volume=67 |issue=22 |pages=7861–7864 |doi=10.1021/jo025868h |issn=0022-3263}}</ref> [[Chemistry:Homolysis|Homolytic]] cleavage of O-I bond generates CO<sub>2</sub> and vinyl radical. Vinyl radical recombines with iodide radical to form vinyl iodide.
[[File:Modified Hunsdiecker reaction.jpg|center|Modified Hunsdiecker reaction]]

==== Iododesilylation ====

'''Iododesilylation''' is a substitution reaction of silyl group for iodide. The advantages of iododesilylation are that it avoids toxic tin reagent and intermediate vinyl silyl are stable, nontoxic and easily handled and stored. Vinyl silyl can be made from terminal alkyne or other methods.

The Kishi's group reported a mild preparation of vinyl iodide from vinyl silyl using NIS in mixture of [[Chemistry:Acetonitrile|acetonitrile]] and [[Chemistry:Chloroacetonitrile|chloroacetonitrile]].<ref>{{Cite journal |last=Stamos |first=Dean P |last2=Taylor |first2=Andrew G |last3=Kishi |first3=Yoshito |date=1996-11-25 |title=A mild preparation of vinyliodides from vinylsilanes |url=https://www.sciencedirect.com/science/article/pii/S004040399602000X |journal=Tetrahedron Letters |volume=37 |issue=48 |pages=8647–8650 |doi=10.1016/S0040-4039(96)02000-X |issn=0040-4039}}</ref> They observed retention of olefin geometry in some vinyl silyl substrates while inversion in others. They reasoned that the R group's size had an effect on the geometry of the olefin. If the R group is small, the solvent [[Chemistry:Acetonitrile|acetonitrile]] can participate in the reaction leading to inversion of the olefin's geometry. If the R group is big, the solvent is unable to participate, leading to retention of olefin's geometry
[[File:Kishi's group iododesilylation method.jpg|center|Kishi's group iododesilylation method]]

Zakarian's group then decided to run the reaction in [[Chemistry:Hexafluoro-2-propanol|HFIP]], which gave high retention of olefin geometry.<ref>{{Cite journal |last=Ilardi |first=Elizabeth A. |last2=Stivala |first2=Craig E. |last3=Zakarian |first3=Armen |date=2008-05-01 |title=Hexafluoroisopropanol as a Unique Solvent for Stereoselective Iododesilylation of Vinylsilanes |url=https://pubs.acs.org/doi/10.1021/ol800341z |journal=Organic Letters |language=en |volume=10 |issue=9 |pages=1727–1730 |doi=10.1021/ol800341z |issn=1523-7060}}</ref> They reasoned that HFIP is a low nucleophilicity solvent, unlike acetonitrile. In addition, they observed accelerated reaction rate because HFIP activate NIS by [[Chemistry:Hydrogen bond|hydrogen bond]]ing.
[[File:Zakarian's group HFIP iododesilylation method.jpg|center|Zakarian's group HFIP iododesilylation method]]

Unfortunately, iododesilylation under those conditions (above) can potentially yield multiple byproducts in highly functionalized molecules with oxygen functional groups. Vilarrasa and Costa's group hypothesized that radical reactions producing [[Chemistry:Hydrogen iodide|HI]] and I<sub>2</sub> help facilitate cleavage in alcohol's [[Chemistry:Protecting group|protecting group]] and may add into other alkene bonds.<ref>{{Cite journal |last=Sidera |first=Mireia |last2=Costa |first2=Anna M. |last3=Vilarrasa |first3=Jaume |date=2011-09-16 |title=Iododesilylation of TIPS-, TBDPS-, and TBS-Substituted Alkenes in Connection with the Synthesis of Amphidinolides B/D |url=https://pubs.acs.org/doi/10.1021/ol2020187 |journal=Organic Letters |language=en |volume=13 |issue=18 |pages=4934–4937 |doi=10.1021/ol2020187 |issn=1523-7060}}</ref> They experimented with the use of [[Chemistry:Silver|silver]] additives such as [[Chemistry:Silver acetate|silver acetate]] and [[Chemistry:Silver carbonate|silver carbonate]] in which the silver can react with the excess iodide to form [[Chemistry:Silver iodide|silver iodide]]. They achieved better conversions with these conditions.

=== Name reactions ===

Some famous vinyl iodide synthesis methods involve conversion of [[Chemistry:Aldehyde|aldehyde]] or [[Chemistry:Ketone|ketone]] to vinyl iodide. Barton's [[Chemistry:Hydrazone iodination|hydrazone iodination]] method involves addition of [[Chemistry:Hydrazine|hydrazine]]s to [[Chemistry:Aldehyde|aldehyde]] or [[Chemistry:Ketone|ketone]] to form [[Chemistry:Hydrazone|hydrazone]]. Then the [[Chemistry:Hydrazone|hydrazone]] is converted to vinyl iodide by addition of iodide and DBU.<ref>{{Cite journal |last=Barton |first=D. H. R. |last2=O'Brien |first2=R. E. |last3=Sternhell |first3=S. |date=1962-01-01 |title=88. A new reaction of hydrazones |url=https://pubs.rsc.org/en/content/articlelanding/1962/jr/jr9620000470 |journal=Journal of the Chemical Society |language=en |issue=0 |pages=470–476 |doi=10.1039/JR9620000470 |issn=0368-1769}}</ref><ref>{{Cite journal |last=Barton |first=Derek H. R. |last2=Bashiardes |first2=George |last3=Fourrey |first3=Jean-Louis |date=1988-01-01 |title=Studies on the oxidation of hydrazones with iodine and with phenylselenenyl bromide in the presence of strong organic bases; an improved procedure for the synthesis of vinyl iodides and phenyl-vinyl selenides |url=https://www.sciencedirect.com/science/article/pii/S0040402001851024 |journal=Tetrahedron |volume=44 |issue=1 |pages=147–162 |doi=10.1016/S0040-4020(01)85102-4 |issn=0040-4020}}</ref> This method has been used in natural product synthesis of Taxol by Danishefsky<ref>{{Cite journal |last=Danishefsky |first=Samuel J. |last2=Masters |first2=John J. |last3=Young |first3=Wendy B. |last4=Link |first4=J. T. |last5=Snyder |first5=Lawrence B. |last6=Magee |first6=Thomas V. |last7=Jung |first7=David K. |last8=Isaacs |first8=Richard C. A. |last9=Bornmann |first9=William G. |last10=Alaimo |first10=Cheryl A. |last11=Coburn |first11=Craig A. |last12=Di Grandi |first12=Martin J. |date=1996-01-01 |title=Total Synthesis of Baccatin III and Taxol |url=https://pubs.acs.org/doi/10.1021/ja952692a |journal=Journal of the American Chemical Society |language=en |volume=118 |issue=12 |pages=2843–2859 |doi=10.1021/ja952692a |issn=0002-7863}}Danishefsky, Samuel J., et al. "Total synthesis of baccatin III and taxol." Journal of the American Chemical Society 118.12 (1996): 2843-2859</ref> and Cortistatin A by Shair.<ref>{{Cite journal |last=Lee |first=Hong Myung |last2=Nieto-Oberhuber |first2=Cristina |last3=Shair |first3=Matthew D. |date=2008-12-17 |title=Enantioselective Synthesis of (+)-Cortistatin A, a Potent and Selective Inhibitor of Endothelial Cell Proliferation |url=https://pubs.acs.org/doi/10.1021/ja8071918 |journal=Journal of the American Chemical Society |language=en |volume=130 |issue=50 |pages=16864–16866 |doi=10.1021/ja8071918 |issn=0002-7863}}</ref>
Another method is the [[Chemistry:Takai olefination|Takai olefination]] which uses [[Chemistry:Iodoform|iodoform]] and [[Chemistry:Chromium(II) chloride|chromium(II) chloride]] to make vinyl iodide from aldehyde with high [[Chemistry:Stereoselectivity|stereoselectivity]] for E geometry.<ref>{{Cite journal |last=Takai |first=K. |last2=Nitta |first2=K. |last3=Utimoto |first3=K. |date=November 1986 |title=Simple and selective method for aldehydes (RCHO) -> (E)-haloalkenes (RCH:CHX) conversion by means of a haloform-chromous chloride system |url=https://pubs.acs.org/doi/abs/10.1021/ja00283a046 |journal=Journal of the American Chemical Society |language=en |volume=108 |issue=23 |pages=7408–7410 |doi=10.1021/ja00283a046 |issn=0002-7863}}</ref> For high [[Chemistry:Stereoselectivity|stereoselectivity]] for Z geometry, Stork-Zhao olefination proceeds by Wittig-like reaction. High yields and Z [[Chemistry:Stereoselectivity|stereoselectivity]] occurred at low temperature and at the presence of HMPA.<ref>{{Cite journal |last=Stork |first=Gilbert |last2=Zhao |first2=Kang |date=1989-01-01 |title=A stereoselective synthesis of (Z)-1-iodo-1-alkenes |url=https://www.sciencedirect.com/science/article/pii/S0040403900996400 |journal=Tetrahedron Letters |volume=30 |issue=17 |pages=2173–2174 |doi=10.1016/S0040-4039(00)99640-0 |issn=0040-4039|doi-access=free }}</ref>
[[File:Stork-Zhao Olefination.jpg|center|Stork-Zhao Olefination]]
Below is example of employing both Takai olefination and Stork-Zhao olefination in total synthesis of (+)-3-(E)- and (+)-3-(Z)-Pinnatifidenyne.<ref>{{Cite journal |last=Kim |first=Hyoungsu |last2=Choi |first2=Won Jun |last3=Jung |first3=Jaeyoon |last4=Kim |first4=Sanghee |last5=Kim |first5=Deukjoon |date=2003-08-01 |title=Construction of Eight-Membered Ether Rings by Olefin Geometry-Dependent Internal Alkylation: First Asymmetric Total Syntheses of (+)-3-( E )- and (+)-3-( Z )-Pinnatifidenyne |url=https://pubs.acs.org/doi/10.1021/ja035538u |journal=Journal of the American Chemical Society |language=en |volume=125 |issue=34 |pages=10238–10240 |doi=10.1021/ja035538u |issn=0002-7863}}</ref>
[[File:Employment of Takai and Stork-Zhao olefination by Kim's group.jpg|center|Employment of Takai and Stork-Zhao olefination by Kim's group]]

=== Elimination method ===

Vinyl iodides are rarely by made an elimination reaction of [[Chemistry:Vicinal|vicinal]] diiodide because it tends to decompose to alkene and iodide.<ref>{{Cite book |last=Katritzky |first=Alan R. |url=https://books.google.com/books?id=BPcxrmIgLKMC |title=Comprehensive Organic Functional Group Transformations: Synthesis: carbon with one heteroatom attached by a single bond |last2=Meth-Cohn |first2=Otto |last3=Rees |first3=Charles Wayne |date=1995-12-15 |publisher=Elsevier |isbn=978-0-08-042323-4 |language=en}}</ref> The Baker group have shown using decarboxylation, elimination can occur.<ref>{{Cite journal |last=Baker |first=Raymond |last2=Castro |first2=Jose L. |date=1990-01-01 |title=Total synthesis of (+)-macbecin I |url=https://pubs.rsc.org/en/content/articlelanding/1990/p1/p19900000047 |journal=Journal of the Chemical Society, Perkin Transactions 1 |language=en |issue=1 |pages=47–65 |doi=10.1039/P19900000047 |issn=1364-5463}}</ref>
[[File:Baker's group elimination method.jpg|center|Baker's group elimination method]]

==See also==
* List of functional groups
* [[Physics:Group contribution method|Group contribution method]]

== References ==
{{reflist}}


[[Category:Alkene derivatives]]
[[Category:Chemical synthesis]]
[[Category:Organoiodides]]

{{Sourceattribution|Vinyl iodide functional group}}