The trans-disubstituted-N-benzyl pyrrolidine 10 is prepared in enantiomerically homogeneous form from cis-4-hydroxy-D-proline (4) in an efficient sequence. The key step involves an SN2 displacement of the methanesulfonate of alcohol 5 with azide ion and occurs without participation of the basic ring nitrogen. The stereochemical outcome, which is contrary to that reported for the related systems 15 and 16, suggests that a mechanism involving the proposed intermediate 19a is improbable. The cis-derivative 14 is prepared by an identical sequence of reactions beginning with trans-4-hydroxy-L-proline. Compound 10 is the precursor to the potent DNA gyrase inhibitor 1 and several related analogs.
反式二取代的N-苄基
吡咯烷10是通过高效的反应序列从顺式-4-氢氧基-
D-脯氨酸(4)制备得到的,且具有对映体均匀性。关键步骤涉及醇5的
甲磺酸酯与
叠氮离子的SN2取代反应,并且在此过程中不涉及基本环氮原子的参与。其立体
化学结果与相关系统15和16的报告相反,表明涉及所提出的中间体19a的机制是不太可能的。顺式衍
生物14是通过与反式-4-氢氧基-
L-脯氨酸相同的反应序列制备的。化合物10是强效DNA旋转酶
抑制剂1及其若干相关类药物的前体。