Chemistry:Casiraghi formylation
From HandWiki
In organic synthesis, the Casiraghi formylation is the formation of a salicylaldehyde from a phenol and paraformaldehyde. The reaction requires a strong Brønsted base and a weak Lewis acid, and gives a methanol coproduct:[1]
- (H
2CO)
2n + nB + nLA + nHArOH → nHC(=O)ArOH + n[HB][LA:OMe]
Formally, it combines the Cannizzaro disproportionation with a directed Friedel-Crafts acylation.
In Casiraghi's original 1978 formulation, Grignard reagents served as both the hindered base and Lewis acid.[2][3]
Applications include the synthesis of tocopherol derivatives.[4]
References
- ↑ Hofsløkken, Nini U.; Skattebøl, Lars; Johansson, Fredrik; Bertilsson, Sophie K.; Andersson, Pher G.; Møller, Jørgen; Senning, Alexander; Yao, Xin-Kan et al. (1999). "Convenient Method for the ortho-Formylation of Phenols." (in en). Acta Chemica Scandinavica 53 (53): 258–262. doi:10.3891/acta.chem.scand.53-0258. ISSN 0904-213X. http://actachemscand.org/doi/10.3891/acta.chem.scand.53-0258. Retrieved 4 Nov 2023.
- ↑ Casiraghi, Giovanni; Casnati, Giuseppe; Puglia, Giuseppe; Sartori, Giovanni; Terenghi, Giuliana (1980). "Selective reactions between phenols and formaldehyde. A novel route to salicylaldehydes" (in en). Journal of the Chemical Society, Perkin Transactions 1: 1862. doi:10.1039/p19800001862. ISSN 0300-922X.
- ↑ Aldred, Robert; Johnston, Robert; Levin, Daniel; Neilan, James (28 Feb 1994). "Magnesium-mediated ortho-specific formylation and formaldoximation of phenols". Journal of the Chemical Society, Perkin Transactions 1: 1823–1831. doi:10.1039/p19940001823. https://www.thevespiary.org/library/Files_Uploaded_by_Users/QuantumDude/Articles/Magnesium-mediated%20ortho-Specific%20Formylation%20and%20Formaldoximation.pdf. Retrieved 4 Nov 2023.
- ↑ Alsabil, Khaled; Viault, Guillaume; Suor-Cherer, Sorphon; Helesbeux, Jean-Jacques; Merza, Joumaa; Dumontet, Vincent; Peña-Rodriguez, Luis Manuel; Richomme, Pascal et al. (2017-12-07). "Efficient ortho-formylation in vitamin E series, application to the semi-synthesis of natural 5- and 7-formyl-δ-tocotrienols revealing an unprecedented 5-bromo-7-formyl exchange". Tetrahedron 73 (49): 6863–6870. doi:10.1016/j.tet.2017.10.039. ISSN 0040-4020.
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