Study on tert-Butyl Radical-Initiated 1,2-Alkynyl Migration

Abstract

A new tert-butyl radical-induced 1,2-alkynyl migration reaction is reported. By using the characteristics of in-situ-generation of tert-butyl radical from pivalaldehyde mediated by di-tert-butyl peroxide (DTBP), tert-butyl radical-triggered addition and alkynyl migration of the preformed 1,4-enynes led to the synthesis of a series of α-alkynyl ketones with good to excellent yields, thereby realizing alkylalkynylation of unactivated olefins. Based on the experimental results and literature reports, a possible reaction mechanism is proposed, which involves tert-butyl radical-triggered addition, 3-exo-dig cyclization of anti-"Baldwin" rule and alkynyl migration process. This reaction has the advantages of high functional group compatibility, metal-free conditions, and simple operation, which provides a feasible and effective synthetic strategy for the bifunctionalization of unactivated olefins.

Recent Advances in Radical Transformations of Propargylic Alcohols

“…Based on the foregoing strategies, Tu's group [43] and Xiang's group [44] independently reported the oxidative alkylation/alkynylation of 1,4-enynols 30 with alkyl aldehydes 81 via di-tert-butyl peroxide (DTBP)-mediated alkyl aldehyde decarbonylation and 1,2-alkynyl migration for the synthesis of two new CÀ C bonds to yield a wide range of quaternary carbon-containing but-3-yn-1-ones 82 in moderate to good yields (Scheme 32). Various alkylaldehydes, including primary, secondary and tertiary substrates, were strongly compatible with this transformation under standard conditions.…”