An N‐propargyl pyrroloimidazolone with syn stereochemistry derived from L‐proline serves as a starting material for the diastereoselective synthesis (>95:5 dr) of propargyl alkynes or allenamides by direct quench of its lithiated intermediate with alkylating agents or aldehydes/ketones, respectively. Use of the epimeric anti pyrroloimidazolone starting material results in reversal of stereochemistry at the propargyl position in the products, without the need to prepare a separate substrate from D‐proline. Lithiation of the syn pyrroloimidazolone and quench with prochiral benzaldehydes without prior transmetalation gives allenamides with crystallographically verified atypical stereochemistry of the benzylic alcohol in >95:5 dr. The epimeric series of benzylic alcohols may also be obtained in >95:5 dr by employing transmetalation with chlorotitanium triisopropoxide prior to aldehyde quench. Density Functional Theory (DFT) computational studies provide a rationale for the change in benzylic alcohol stereochemistry by virtue of differing stereofacial attack in 6,5‐bicyclic (Li) or 6‐membered (Ti) transition states.

中文翻译：

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异构体吡咯并咪唑酮助剂的立体选择性合成N-炔丙基炔烃和轴向手性N-丙二烯

一个Ñ -propargyl pyrroloimidazolone与顺式立体化学衍生自L-脯氨酸用作用于非对映选择性合成的起始原料（> 95:5 DR）由它的锂化中间体的直接淬火炔丙基炔烃或allenamides的分别与烷基化剂或醛/酮， 。使用差向异构的抗吡咯并咪唑酮起始原料可导致产物炔丙基位置的立体化学反应发生逆转，而无需准备与D-脯氨酸分开的底物。syn的锂化吡咯并咪唑酮，在未进行预先金属化的情况下用前手性苯甲醛淬灭，制得的烯丙基酰胺在95：5博士中经结晶学验证为苯甲醇的非典型立体化学。苯甲醇的差向异构体系列也可以在醛淬灭之前通过用三异丙氧基氯钛进行重金属化而以> 95：5 dr得到。密度泛函理论（DFT）的计算研究通过在6,5双环（Li）或6元（Ti）过渡态中不同的立体界面侵蚀，为苯甲醇立体化学的变化提供了理论依据。