Diastereoselectively Switchable Enantioselective Trapping of Carbamate Ammonium Ylides with Imines

Abstract

The diastereoselectively switchable enantioselective trapping of protic carbamate ammonium ylides with imines is reported. The intriguing Rh(2)(OAc)(4) and chiral Brønsted acid cocatalyzed three-component Mannich-type reaction of a diazo compound, a carbamate, and an imine provides rapid and efficient access to both syn- and anti-α-substituted α,β-diamino acid derivatives with a high level control of chemo-, diastereo-, and enantioselectivity.

Stereoselective Synthesis of Functionalized Pyrrolidines by the Diverted N−H Insertion Reaction of Metallocarbenes with β‐Aminoketone Derivatives

“…[20] We additionally propose that cyclization occurs via a highly ordered transition state C involving a proton transfer from the carbamate/aniline nitrogen to the ketone carbonyl assisted by the ester carbonyl group, thus explaining the full selectivity for the cis-product 5p/3a. Importantly, these results support the view that the N-H insertion of rhodium metallocarbene into carbamates occurs via a stepwise mechanism [21] rather than a concerted process, as previously proposed.…”

Stereoselective Synthesis of Functionalized Pyrrolidines by the Diverted N−H Insertion Reaction of Metallocarbenes with β‐Aminoketone Derivatives

“…[20] We additionally propose that cyclization occurs via a highly ordered transition state C involving a proton transfer from the carbamate/aniline nitrogen to the ketone carbonyl assisted by the ester carbonyl group, thus explaining the full selectivity for the cis-product 5p/3a. Importantly, these results support the view that the N-H insertion of rhodium metallocarbene into carbamates occurs via a stepwise mechanism [21] rather than a concerted process, as previously proposed. Finally, pyrrolidines 5a and 5v were deprotected under standard conditions to give N-H pyrrolidines 7 and 8, respectively (Scheme 7).…”

Progress of Cooperative Catalysis in Organic Synthesis

“…研究表明选择不同构型的金鸡 纳伯胺和金属配体, 可以高收率、高 ee 值和较高的 dr 值获得各种构型的产物. 4 and chiral phosphoric acid 利用过渡金属 Rh 或 Ru 与有机磷酸的共催化体系, 胡文浩研究组还报道了一系列金属卡宾和亚胺参与, 以 多组分 Mannich 反应为主要反应, 成功构筑手性环缩 醛 [49] 、a,β-二氨酸衍生物 [50] 及全取代四氢异喹琳衍生物 的方法 [51] . 例如, 以芳基重氮醋酸酯、芳胺、苄氧羰基 胺及 2-醛基肉桂酸酯为原料, 通过分子内 Mannich 反应 及串联的氮杂 Michael 加成反应, 以中等收率、高立体 选择性地构建了一系列骨架多样、结构丰富的含季碳的 全取代四氢异喹琳衍生物 [51] , …”