Chiral oxazaphosphorinanes, derived from (-)-8-amino menthol are alkylated with good to excellent diastereoselectivities. The regioselectivity in the alkylation is dependent on the base used for deprotonation. The ethyl oxazaphosphorinanes are alkylated at the nitrogen substituent after deprotonation with n-butyllithium, but in α-position to the phosphorous atom by deprotonation with LDA. On the contrary, the oxazaphosphorinanes with an alkyl substituent at the nitrogen atom or benzyl oxazaphosphorinane are alkylated in α-position to the phosphorous atom after deprotonation with either n-butyllithium or LDA.
来源于(-)-8-
氨基薄荷醇的手性氧氮
磷烷被烷基化,具有良好到优异的二面体选择性。烷基化的区域选择性取决于用于去质子的碱。经过n-丁基
锂去质子化后的乙基氧氮
磷烷在氮取代基上烷基化,而通过
LDA去质子化则在
磷原子的α位进行烷基化。相反,带有氮原子烷基取代基的氧氮
磷烷或苄基氧氮
磷烷在经过n-丁基
锂或
LDA去质子化后,都在
磷原子的α位进行烷基化。