Synthesis of Imidazoles and Oxazoles via a Palladium-Catalyzed Decarboxylative Addition/Cyclization Reaction Sequence of Aromatic Carboxylic Acids with Functionalized Aliphatic Nitriles
efficient approach for the assembly of multiply substituted imidazoles and oxazoles in a single-step manner. These transformations are based on a decarboxylation addition and annulation of readily accessible aromatic carboxylic acids and aliphatic nitriles and exhibit good functional group compatibility and a high step economy. The reaction is scalable, and as-prepared products could be transformed into practical
for the synthesis of 0-substituted cyanohydrins from aldehydes and ketones, in the absence of solvent, employing minimum amounts of the corresponding cyanides has been optimised. Aldehydes react more rapidly than ketones using triethylamine as catalyst offering in both cases almost quantitative yields of the corresponding O-trimethylsilyl, O-methoxycarbonyl, O-benzoyl and O-acetyl cyanohydrins.
A palladium‐catalyzed tandem reaction of cyanomethyl benzoates with arylboronic acids has been achieved. Substitution at the 2‐position of cyanomethyl benzoates was found to be crucial for the selective synthesis of oxazoles and isocoumarins. Cyanomethyl benzoates afforded 2,4‐diaryloxazoles as products, while 2‐benzoyl‐substituted cyanomethyl benzoates delivered 3‐benzoyl‐4‐aryl‐isocoumarins selectively
DABCO-Mediated Synthesis and Biological Activity of Cyanohydrin Esters
作者:H. M. R. Hoffmann、Z. M. Ismail、Reiner Hollweg、Abdul R. Zein
DOI:10.1246/bcsj.63.1807
日期:1990.6
Cyanohydrinesters 1–31 have been prepared from α-ketonitriles and aldehydes using DABCO (1,4-diazabicyclo[2.2.2] octane) as nucleophilic acylation catalyst. The modified piperonal 8 was found to inhibit the formation of thromboxane synthetase.
readily available simple arenes and functionalized aliphatic nitriles. This transformation involves palladium-catalyzed C–H activation, carbopalladation and a tandem annulation sequence in one pot. Notably, the reaction proceeds efficiently under redox-neutral conditions, and exhibits high atom-economy. Deuterium-labeling experiments suggested that C–H bond cleavage of the simple arenes might be the rate-determining