[1,3]-Transfer of Chirality during the Nicholas Reaction in γ-Benzyloxy Propargylic Alcohols
作者:David D. Díaz、Miguel A. Ramírez、Víctor S. Martín
DOI:10.1002/chem.200501127
日期:2006.3.8
gamma-acetylenic diols with BF3 x OEt2 provides bis-homopropargylic alcohols. The reaction occurs within seconds, tolerates a wide range of functionalities, and provides good yields. When the ether group is located at a stereochemically defined carbon atom, the rearrangement occurs with high stereoselectivity, transferring the chirality of the carbinol center to the newly created stereocenter. The cleavage
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。