Metalated Nitriles: Organolithium, -magnesium, and -copper Exchange of α-Halonitriles
作者:Fraser F. Fleming、Zhiyu Zhang、Wang Liu、Paul Knochel
DOI:10.1021/jo047877r
日期:2005.3.1
dimethylcuprate reagents generating reactive, metalated nitriles. The rapid halogen−metal exchange with alkyllithium and Grignard reagents allows selective exchange in the presence of reactive carbonyl electrophiles, including aldehydes, providing a high-yielding alkylation protocol. Lithiated and magnesiated nitriles react with propargyl bromide by SN2 displacement whereas organocopper nitriles react
α-卤代腈与烷基锂,有机镁和二甲基cup酸锂试剂反应生成活性的金属化腈。与烷基锂和格氏试剂的快速卤素金属交换可在存在醛的反应性羰基亲电试剂存在下进行选择性交换,从而提供了高产率的烷基化方案。锂化和氧化镁腈通过S N 2置换与炔丙基溴反应,而有机铜腈通过S N 2'置换反应,与C-金属化腈的形成相关。
Metalated Nitriles: Halogen−Metal Exchange with α-Halonitriles
作者:Fraser F. Fleming、Zhiyu Zhang、Paul Knochel
DOI:10.1021/ol036202s
日期:2004.2.1
[reaction: see text] Alpha-halonitriles react with organometallic reagents in a facile halogen-metal exchange. The halogen-metal exchange is extremely fast with Grignard and alkyllithium reagents, generating metalated nitriles in situ with aldehyde, ketone, acid chloride, and acylcyanide electrophiles. Sequential halogen-metal exchange and methylation of conformationally constrained nitriles is highly
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
(dimethylsilyl)acetonitriles (Me2HSiCR3R4CN) react spontaneously with aldehydes in DMSO to give β-hydroxynitriles in good to high yields. The addition to ketones is effectively promoted by using MgCl2 or CaCl2. (Dimethylsilyl)acetonitrile (Me2HSiCH2CN) shows lower reactivity than the α-alkylated analogues. However, the parent reagent adds efficiently to aldehydes and ketones under catalysis by AcOLi or MgCl2.