Isoborneolを基盤とした1,3-アミノアルコール型リガンドを用いるジエチル亜鉛のアルデヒドに対する不斉エチル化反応

抄録

Chiral aminoalcohols are promising catalysts in the enantioselective nucleophilic addition reaction of organozinc reagents to carbonyl compounds. In fact, many chiral 1,2-aminoalcohol-type ligands were known to give optical active 1-phenylpropan-1-ol over 98% ee in the reaction of diethylzinc with benzaldehyde. However, investigations on 1,3- or 1,4-aminoalcohol-type ligands would be still lacking. Thus, we designed and synthesized several new 1,3-aminoalcohol-type ligands, (1S,2R)-10-(dialkylamino)isoborneols. Initially, the reaction of diethylzinc to benzaldehyde with 5 mol % of ligands was examined. Of all, the ligand bearing granatanine as a dialkylamine moiety gave the best results (99 % yield, 94 % ee for R-isomer). The ligand also gave good enantioselectivity in the reaction using other aldehydes.

Scheme 1