Chiral acetals derived from aldehydes and (-)-(2R,4R)-2,4-pentanediol are cleaved selectively by organoaluminumreagents. The reaction proceeds via the retentive-alkylation process with >95% selectivities in most cases. Trialkylaluminum reagent is utilized for higher alkyl transfers, but for smaller alkyl transfers, a newreagent system, combining trialkylaluminum and the halophenols such as pentafluorophenol
Some chiralacetals are cleaved by organoaluminum reagents. The products are formed diastereoselectively, and the removal of the chiral auxiliary affords optically active alcohols.
Nucleophilic cleavages of acetals using organotitanium reagents. A new synthesis of chiral alcohols
作者:Atsunori Mori、Keiji Maruoka、Hisashi Yamamoto
DOI:10.1016/s0040-4039(01)81455-6
日期:1984.1
A highlychemo- and stereoselective cleavage of acetals derived from (−)-(2R,4R)-2,4-pentanediol with organotitanium reagents has been demonstrated. The reaction proceeds under mild conditions in excellent yield and high chemoselectivity to give, after removal of auxiliary, the chiral alcohols of high enantiopurities. In addition, complexation of chiral acetals and TiCl4 followed by treatment with