Ireland-Claisen rearrangement of secondary allyl acetate revisited: inevitable C-silylation circumvented by one-pot application of excessive LDA/TMSCl and TBAF
摘要:
Yield lowering C-silylation was found to be inevitable in all the six tested examples of stoichiometric LDA/TMSCl promoted Ireland-Claisen rearrangement of secondary allyl acetates. In order to circumvent this problem, a higher yielding protocol was devised after the isolated by-products were found to be excellent substrates for further rearrangement. Thus, excessive LDA/TMSCl was applied to achieve complete 3,3'-sigmatropic shift of the substrates, and the resulting mixtures of normal and alpha-silylated gamma,delta-unsaturated carboxylic acids was then desilylated by one-pot application of TBAF. (c) 2012 Elsevier Ltd. All rights reserved.
Enantioselective C3‐Allylation of Pyridines via Tandem Borane and Palladium Catalysis
作者:Jun‐Jie Tian、Rui‐Rui Li、Gui‐Xiu Tian、Xiao‐Chen Wang
DOI:10.1002/anie.202307697
日期:2023.8.21
A one-pot, three-step method for highly enantioselective C3-allylation reactions of pyridines was developed. The method involved borane-catalyzed dearomative pyridine hydroboration, palladium-catalyzed enantioselective allylation of the dearomatized intermediate, and finally oxidation by air. The method was applicable to a broad range of pyridines, N-heteroarenes, and allylic esters.