描述了高度区域和立体选择性的分子内[1,5]-氢转移过程。用BF3 x OEt2处理γ-苄基保护的Co2(CO)6-α,γ-炔二醇可提供双均炔丙基醇。反应在几秒钟内发生,可耐受多种功能,并提供良好的收率。当醚基位于立体化学定义的碳原子上时,重排会以高立体选择性发生,从而将甲醇中心的手性转移至新创建的立体中心。当存在另外的苄基醚时,苄氧基的裂解是完全区域选择性的。评价了该新方法在密集取代的底物中的范围和局限性,还描述了可能的竞争反应和/或立体化学影响。
are most commonly protected as ethers and esters, where in alkyl and benzyl ethers are strong protective groups while others, like THP, TBS, TPS and MEM/MOM ethers are acid labile. Among all other hydroxyl protecting groups, Silyl ethers are the most frequently used protecting groups because they are easily and efficiently installed and are stable to a variety of useful reagents and reaction conditions
A stereoselective total synthesis of (−)-andrachcinidine via an olefin cross-metathesis protocol
作者:Palakodety Radha Krishna、G. Dayaker
DOI:10.1016/j.tetlet.2007.08.053
日期:2007.10
A stereoselectivetotalsynthesis of 1-(2S,6R)-6-[(2S)-2-hydroxypentyl]-hexahydro-2-pyridinylacetone, (−)-andrachcinidine is reported. The strategy utilizes olefincross-metathesis and intramolecular SN2 cyclization as the key steps.
Abstract Herein we report the stereoselective total synthesis of Exserolide F. The key step involves triflic acid catalyzed highly regioselective intramolecular cyclization of an O-alkynyl benzoicacid derivative to accomplish the core isocoumarin skeleton of the natural product via 6-endo-dig mode of cyclization. The other important steps are: Sharpless asymmetric epoxidation, Barbier propargylation