Reaction between hydrazines and chiral α-acetylenic ketones: synthesis of novel enantiomerically pure pyrazolyl-β-amino alcohols
作者:Gemma Cabarrocas、Montserrat Ventura、Miguel Maestro、José Mahı́a、José M Villalgordo
DOI:10.1016/s0957-4166(00)00204-4
日期:2000.6
A simple and efficient methodology toward the stereoselective synthesis of novel, enantiomerically pure, pyrazolyl-β-amino alcohols is presented. Thus, when hydrazines 4a,b were allowed to react at 0°C with chiral α-acetylenic ketones of type 3, pyrazolyl oxazolidine derivatives 5a–d were formed with total regioselectivity in 92–97% yield. Subsequent oxazolidine ring opening by means of TFA, and re-protection
提出了一种简单有效的方法,用于立体选择性合成新型,对映体纯的吡唑基-β-氨基醇。因此,当肼4a,b在0℃下与3型手性α-炔基酮反应时,形成吡唑基恶唑烷衍生物5a – d,其总区域选择性为92–97%。随后通过TFA恶唑烷开环,并重新保护氨基作为N- Boc衍生物,得到对映体纯的氨基醇7a - d。