✍ Scribed by Niall W.A. Geraghty; Elaine M. Hernon
No coin nor oath required. For personal study only.
The photomediated generation of a-hydroxyalkyl radicals from simple acyclic and cyclic alcohols, and acyclic diols, and their subsequent carbon-carbon bond forming reaction with propiolate esters and acetylenedicarboxylates, gives a mixture of a b-(hydroxyalkyl)enoate, the result of a formal cis addition, and the unsaturated lactone (c-butenolide) resulting from the spontaneous cyclization of the corresponding trans addition product. Treatment of the cis adduct with NBS converts it to the same lactone, and so the method overall constitutes a particularly direct route to this important structural unit. Cyclic alcohols give rise to spiro-c-butenolides. The use of supported photomediators simplifies product isolation and allows for the recovery and reuse of the photomediator.
📜 SIMILAR VOLUMES
Allylic propiolates react with tributyl-or triphenylstannane to yield a-(stannyljmethylene-y-butyrolactones. a-Methylene-y-butyrolactones are easily prepared by destannylation.
An improved procedure for the efficient synthesis of I~-halobutenolides was developed. The Pd(0)catalyzed coupling reactions of 13-halobutenolides with terminal alkynes or organozinc reagents, i.e., 1-alkenyl, aryl, and alkyl zinc reagents, to afford 13-substituted butenolides were carefully studied