Synthesis of Nitrile‐Bearing Quaternary Centers by an Equilibrium‐Driven Transnitrilation and Anion‐Relay Strategy
作者:Sébastien Alazet、Michael S. West、Purvish Patel、Sophie A. L. Rousseaux
DOI:10.1002/anie.201903215
日期:2019.7.22
preparation of nitrile‐containing building blocks is of interest due to their utility as synthetic intermediates and their prevalence in pharmaceuticals. As a result, significant efforts have been made to develop methods to access these motifs which rely on safer and non‐toxic sources of CN. Herein, we report that 2‐methyl‐2‐phenylpropanenitrile is an efficient, non‐toxic, electrophilic CN source for
organolithiums, Grignardreagents, or zincates to sulfinylnitriles triggers a facile sulfinyl–metal exchange to afford N‐ or C‐metalated nitriles. Sulfinyl–magnesium exchange–alkylations efficiently install quaternary and tertiary centers, even in the case of tertiary sulfinylnitriles that contain a highly acidic methine proton. α‐Sulfinylalkenenitriles afford moderately nucleophilic magnesiated nitriles, and
Arylthio-Metal Exchange of α-Arylthioalkanenitriles
作者:Dinesh Nath、Melanie C. Skilbeck、Iain Coldham、Fraser F. Fleming
DOI:10.1021/ol403020s
日期:2014.1.3
The addition of BuLi, Bu3MgLi, Et2ZnBuLi, or Me2CuLi to alpha-arylthioalkanenitriles triggers an arylthio-metal exchange. NMR spectroscopic analyses implicate organometallic attack on sulfur forming a three-coordinate sulfidate as the key intermediate. Electrophilic trapping affords tertiary and quaternary nitriles in high yield. The method addresses the challenge of improving the functional group tolerance and preventing polyalkylations.
Nitrile Alkylations through Sulfinyl-Metal Exchange
作者:Dinesh Nath、Fraser F. Fleming
DOI:10.1002/anie.201105630
日期:2011.12.2
Triple alkylation: Phenylsulfinyl‐ and phenylthioacetonitrile can function as trianion equivalents of acetonitrile by sequential alkylation and sulfinyl–metal exchange (see scheme; mCPBA=meta‐chloroperoxybenzoic acid). The metalated nitriles alkylate a range of electrophiles to obtain nitriles with quaternary centers. The sulfinyl–metal exchange proceeds under very mild conditions and has a high functional‐group