A N-heterocyclic carbene (NHC) catalyzed transformylation of 1░, 2░, and 3░ alcohols in the presence of methyl formate as the formyl transfer reagent provides a broad range of formates in good yields. The reaction employs low catalyst loadings, is insensitive to common nitrogen and oxygen protecting groups and can be achieved in the presence of a number of heterocycles.
J. E. M. Fernando, A. Levens, D. Moock, D. W. Lupton, Synthesis, 2017, 49, 3505-3510.
In the presence of a Zn-cluster catalyst, alcohols are efficiently converted to the corresponding acetates in very good yields just by refluxing in EtOAc. The mild reaction conditions enabled a selective acetylation of various functionalized alcohols even in the presence of highly nucleophilic aliphatic amino groups.
T. Iwasaki, Y. Maegawa, Y. Hayashi, T. Ohshima, K. Mashima, Synlett, 2009, 1659-1663.
Catalytic amounts of alkylidene derivatives of N-heterocyclic carbenes promote transesterification reactions. Because of their strong Br°nsted/Lewis basicity, these organocatalysts can enhance the nucleophilicity of alcohols for acylation reactions with carboxylic esters.
M. BlŘmel, J.-M. Noy, D. Enders, M. H. Stenzel, T. V. Nguyen, Org. Lett., 2016, 18, 2208-2211.
A catalytic transesterification is promoted by a tetranuclear zinc cluster. The mild reaction conditions enabled the reactions of various functionalized substrates to proceed in very good yield. A large-scale reaction under solvent-free conditions offers high environmental and economical advantages.
T. Iwasaki, Y. Maegawa, Y. Hayashi, T. Ohshima, K. Mashima, J. Org. Chem., 2008, 73, 5147-5150.
Silica chloride is an efficient catalyst for esterification of carboxylic acids with alcohols as well as for transesterification of esters by both alcoholysis and acidolysis.
K. V. N. S. Srinivas, I. Mahender, B. Das, Synthesis, 2003, 2479-2482.
Sc(OTf)3 catalyses a direct transesterification of carboxylic esters in boiling alcohols. Methyl, ethyl, isopropyl, and allyl esters were prepared from various substrates in high yields. The application of microwave irradiation led to significantly reduced reaction times.
N. Remme, K. Koschek, C. Schneider, Synlett, 2007, 491-493.
K2HPO4 is an efficient catalyst for transesterifications to produce methyl esters. Various functional groups are tolerated under the mild reaction conditions.
T. Shinada, M. Hamada, K. Miyoshi, M. Higahino, T. Umezawa, Y. Ohfune, Synlett, 2010, 2141-2145.
A mild, functional group tolerant palladium-catalyzed carbonylation of aryl chlorides using atmospheric pressure of carbon monoxide allows the preparation of phenyl esters, alkyl esters and carboxylic acids. Phenyl esters are shown to be useful acylating agents, delivering libraries of carbonyl derivatives, including alkyl, allyl and thioesters, under very mild conditions.
D. A. Watson, X. Fan, S. L. Buchwald, J. Org. Chem., 2008, 73, 7096-7101.
Various alcohols, amines and N-hydroxylamines gave corresponding formylated adducts in high yields by treatment with 2,2,2-trifluoroethyl formate (TFEF). Chemoselective formylation of a primary amine could be readily achieved in the presence of an unprotected primary alcohol.
D. R. Hill, C.-N. Hsiao, R. Kurukulasuriya, S. Wittenberger, Org. Lett., 2002, 4, 111-113.
Transesterification/acylation reactions of secondary alcohols are efficiently catalyzed by N-Heterocyclic carbenes (NHC) at room temperature.
R. Singh, R. M. Kissling, M.-A. Letellier, S. P. Nolan, J. Org. Chem., 2004, 69, 209-212.
A carbene-catalyzed reaction enables a dynamic kinetic resolution of α,α-disubstituted carboxylic esters with up to 99:1 er and 99% yield.
X. Chen, J. Z. M. Fong, J. Xu, C. Mou, Y. Lu, S. Yang, B.-A. Song, Y. R. Chi, J. Am. Chem. Soc., 2016, 138, 7212-7215.
In the presence of sodium acetate, the reaction between 2,2,6-trimethyl-4H-1,3-dioxin-4-one and secondary or tertiary alcohols or primary or secondary amines could be carried out in refluxing tetrahydrofuran. Under these much milder conditions, side products were avoided, and β-keto esters and β-ketoamides were normally obtained in quantitative yields.
V. Sridharan, M. Ruiz, J. C. MenÚndez, Synthesis, 2010, 1053-1057.