Applications of highly enantioenriched alcohols bearing a phenylthio group in the preparation of ring compounds. The two-pot synthesis of an enantiopure spiroacetal pheromone bearing three chiral centers
摘要:
The new chiron (S)-6-phenylthio-2-hexanol (3) was prepared in high enantiomeric excess by baker's yeast reduction of the corresponding ketone. Enantioenriched alcohols 1, 2 and 3, prepared previously by a similar procedure, or their racemic counterparts, were transformed into ring closed compounds 5-methyl-2-(phenylthio)tetrahydrofuran (9), 6-methyl-2-(phenylthio)tetrahydropyran (10), 2-methyl-1-phenylsulfonyl cyclopropane (14), cyclobutane (15), cyclopentane (16), and a bee pheromone, (2S,6R,8S)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane (20). (C) 1997 Elsevier Science Ltd.
Secondary phosphine oxides O=PHR2 (SPOs) were identified as multitalented preligands for the chemoselective Pd‐catalyzedoxidation of alcohols by a hydrogen‐abstracting methodology. SPOs were found to promote the hydrogen‐abstraction step as well as hydrogen transfer to a Michael acceptor by generating a putative active H−Pd species. The catalytic system operates under neutral conditions and was proven