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Journals and Conferences
This review is devoted to the problem of chemoselective formation of ester functions in polyfunctional molecules. The review covers most typical approaches to chemoselective acylation of hydroxy groups in molecules containing an amino, mercapto, or another hydroxy functionality as well as chemoselective esterification of di- and polycarboxylic acids.
Carboxylic acids possessing a strong electron-withdrawing group in the alpha-position undergo facile dehydration upon reaction with carbodiimides to form the corresponding substituted ketenes that can react in situ with alcohols providing esters in a high yield. The ketene formed by the treatment of ethyl 2-methylmalonate with DCC was trapped in situ by a… (More)
[reaction--see text] Carboxylic acids possessing strongly electron withdrawing substituents in the alpha-position in the presence of DCC acylate sterically hindered and chemically sensitive alcohols. The pattern of reactivity, the deuteration experiments, and the formation of a product derived from a [4 + 2] cycloaddition reaction corroborate the existence… (More)
Reaction of N-acylimidazoles possessing an electron-withdrawing group in the alpha position with diarylimines produces beta-lactams in high yields.
Esterification of carboxylic acids capable of forming ketene intermediates upon treatment with carbodiimides permits the selective acylation of alcohols in the presence of phenols lacking strong electron-withdrawing groups. The selectivity of acylations involving highly acidic phenols could be reversed through the addition of catalytic amount of acid.… (More)
The octaethyl triptycenes 7 and 8 were synthesized by Diels-Alder reaction of the octaethylanthracene 4with the corresponding benzynes. Low-temperature NMR spectra of 7 and 8 are consistent with the presence of the fully alternated conformation "a" of C(2) symmetry. However, in the determined crystal structures, the compounds adopt a higher energy… (More)