<i>O</i>-Methylephedrine: A Versatile and Highly Efficient <i>o</i><i>rtho</i>-Directing Group. Synthesis of Enantiopure 1,2-Disubstituted Ferrocene Derivatives
作者:Li Xiao、Roman Kitzler、Walter Weissensteiner
DOI:10.1021/jo015949y
日期:2001.12.1
(R(p))-ferrocene configuration. Subsequently, the chiral auxiliary could be replaced by systems including dimethylamine, acetate, diaryl- or dialkylphosphines to give a number of enantiopure bifunctional 1,2-disubstituted ferrocene derivatives such as (R(p))-N-2-iodo- or (R(p))-N-2-bromoferrocenylmethyldimethylamine or (R(p))-2-acetoxymethyl-1-diphenylphosphinoferrocene. As an application, ferrocenyl diphosphines
O-甲基麻黄碱被确定为二茂铁的邻位锂化反应的非常有效的手性助剂。(1R,2S)-O-甲基麻黄碱[CH(3)NHCH(CH(3))CH(Ph)OCH(3)]与N-二茂铁基甲基-N,N,N-三甲基碘化铵[FcCH(2) N(CH(3))(3)I; Fc =二茂铁基]得到(1R,2S)-N-二茂铁基甲基-O-甲基麻黄碱。用戊烷中的t-BuLi处理该化合物,然后用亲电体碘,二溴四氟乙烷,氯代二苯基膦或二苯甲酮淬灭,得到98%de和(R(p))-二茂铁构型的2-取代的二茂铁。随后,可以用包括二甲胺,乙酸酯,二芳基或二烷基膦在内的体系代替手性助剂,得到许多对映纯的双官能团1,2-二取代的二茂铁衍生物,例如(R(p))-N-2-碘-或(R(p))-N-2-溴二茂铁基甲基二甲基胺或(R(p))-2-乙酰氧基甲基-1-二苯基膦二茂铁。作为应用,二茂铁基二膦仅具有平面(R(p))-二茂铁构型[1,2-(PPh(2))FcCH(2)PR(2),R