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


DÖNDAŞ H. A. , Grigg R., Kilner C.

TETRAHEDRON, vol.59, no.43, pp.8481-8487, 2003 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 59 Issue: 43
  • Publication Date: 2003
  • Doi Number: 10.1016/j.tet.2003.09.032
  • Title of Journal : TETRAHEDRON
  • Page Numbers: pp.8481-8487

Abstract

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, 110degreesC) 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. (C) 2003 Elsevier Ltd. All rights reserved.