Short Syntheses of (-)-<b>(</b>
<b><i>R</i></b>
<b>)</b>-Pyrrolam A and (1<b><i>S</i></b>)-1-Hydroxyindolizidin-3-one
作者:Rainer Schobert、André Wicklein
DOI:10.1055/s-2007-966035
日期:——
(-)-( R)-Pyrrolam A was prepared in five steps, 95% ee and 25% yield, from ( R)-benzyl prolinate. Closure of the pyrrolidine ring was effected by a domino addition-Wittig alkenation reaction with ylide Ph 3 PCCO, immobilized on a polystyrene resin. An indolizidinone was obtained likewise from ( R)-benzyl pipecolate. The reduction of 1-ketopyrrolizidinones and 1-ketoindolizidinones is described.
(-)-(R)-Pyrrolam A 由 (R)-脯氨酸苄酯分五步制备,95% ee 和 25% 产率。吡咯烷环的闭合通过与叶立德 Ph 3 PCCO 的多米诺加成-维蒂希烯化反应实现,固定在聚苯乙烯树脂上。同样由(R)-苄基哌可酸得到吲哚齐酮。描述了 1-ketopyrrolizidinones 和 1-ketoindolizidinones 的还原。
Diazo Tetramic Acids Provide Access to Natural-Like Spirocyclic Δ<sup>α,β</sup>-Butenolides through Rh(II)-Catalyzed O–H Insertion/Base-Promoted Cyclization
3-Diazotetramic acids were found to be valid substrates for the recently discovered approach toward natural-like Δα,β-spirobutenolides via Rh(II)-catalyzed O–H insertion into propiolicacids followed by base-promoted intramolecular Michael addition. The target Δα,β-spirobutenolides were obtained in generally high yields and, in the case of chiral 5-monosubstituted 3-diazotetramic acids, high diastereoselectivity