Exploring Stereogenic Phosphorus: Synthetic Strategies for Diphosphines Containing Bulky, Highly Symmetric Substituents
作者:Francesca Maienza、Felix Spindler、Marc Thommen、Benoît Pugin、Christophe Malan、Antonio Mezzetti
DOI:10.1021/jo020130l
日期:2002.7.1
Diphosphine ligands bearing highly symmetric, bulky substituents at a stereogenic P atom were prepared, exploiting established protocols, which include the use of chiral synthons such as 3,4-dimethyl-2,5-diphenyl-1,3,2-oxazaphospholidine-2-borane (3a) and phenylmethylchlorophosphine borane (10) and the enantioselective deprotonation of dimethylarylphosphine boranes. However, only (Bu(t)())(Me)PCH(2)CH(2)P(Bu(t)Me
利用已建立的方案,包括使用手性合成子,例如3,4-二甲基-2,5-二苯基-1,3,2-氧杂氮磷吡啶-2,制备了在立体异构P原子上具有高度对称,庞大取代基的二膦配体。 -硼烷(3a)和苯基甲基氯膦硼烷(10)和二甲基芳基膦硼烷的对映选择性去质子化。但是,只有(Bu(t)())(Me)PCH(2)CH(2)P(Bu(t)Me(8a)可以由3a制备。二膦(S,S)-1,2-含(2,6-二取代的)双(间苯二甲基膦基)乙烷(((S,S)-8b)和(S,S)-1,2-双(9-蒽甲基膦基)乙烷((S,S)-8c)芳基P取代基是通过埃文斯的P(Ar)(Me)(2)(BH(3))(Ar =异丁基或9-蒽)的斯巴丁碱辅助对映选择性去质子化制备的,但对映选择性不超过37% ee。不对称取代的 亚甲基桥联二膦(2R,4R)-(Ph)(CH(3))PCH(2)P(Mes)(CH(3))((2R,4R)-12)(Mes