X=Y=ZH Systems as potential 1,3-dipoles. Part 58: Cycloaddition route to chiral conformationally constrained (R)-pro-(S)-pro peptidomimetics

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• 作者：Dondas ; H. Ali ; Grigg ; Ronald ; Kilner ; Colin
• 关键词：cilazapril ; ACE inhibitors ; imines ; azomethine ylide ; 1 ; 3-dipolar cycloaddition ; peptidomimetics ; multiplication of chirality
• 刊名：Tetrahedron
• 出版年：2003
• 出版时间：October 20, 2003
• 年：2003
• 卷：59
• 期：43
• 页码：8481-8487
• 全文大小：242 K

文摘

Imines of (1S,9S)-t-butyl-9-amino-octahydro-6,10-dioxo-6H-pyridazino[1,2-a][1,2]diazepine-1-carboxylate undergo thermal (toluene, 110°C) or LiBr-DBU catalysed (MeCN, room temperature) regio- and stereo-specific cycloaddition to a range of chiral dipolarophiles giving enantiopure spiro-cycloadducts in excellent yield. The reactions proceed via intermediate NH azomethine ylides and litho azomethine ylides, respectively and results in the multiplication of chiral centres from 2 (one of which is lost in the process) to 5.