Step saver: Carbonyl groups with lower reactivities can be transformed in the presence of more reactive ones by treatment with PPh3 (or PEt3) and TMSOTf prior to the reaction (see scheme; TMS=trimethylsilyl, Tf=trifluoromethanesulfonyl). This methodology can be applied to reduction and alkylation reactions, and enabled the short asymmetric totalsynthesis of (+)‐centrolobine with the highest overall
Control of Transient Aluminum–Aminals for Masking and Unmasking Reactive Carbonyl Groups
作者:Francis J. Barrios、Brannon C. Springer、David A. Colby
DOI:10.1021/ol401265a
日期:2013.6.21
dimethylaluminum N,O-dimethylhydroxylamine complex, is effective at masking reactivecarbonylgroups in situ from nucleophilic addition. This reagent allows chemoselective addition of reducing reagents, Grignard reagents, organolithiums, Wittig reagents, and enolates into substrates with multiple carbonylgroups. Moreover, the trapped carbonylgroup, a stable aminal, can be unmasked in situ for additional synthetic