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Stereocontrolled Synthesis of Heteroannular Acetals from Functionalized 1,5-Enynes via Radical Cascades—Construction of Quaternary and 1,2-Diquaternary Centres in Polycyclic Systems

Authors
Journal
Tetrahedron
0040-4020
Publisher
Elsevier
Publication Date
Volume
56
Issue
35
Identifiers
DOI: 10.1016/s0040-4020(00)00592-5
Keywords
  • Stereocontrolled Synthesis
  • Heteroannular Acetals
  • 1
  • 5-Enynes
Disciplines
  • Chemistry
  • Mathematics

Abstract

Abstract Sequential, radical-mediated cyclizations of 1,5-enynes have been evaluated with respect to structure, stereochemistry and reactivity. In series A 5- exo-trig, 6- endo-dig cascades are favoured. The unusual 6- endo-dig cyclization is dictated by ring strain. Diastereomeric series B tolerates leakage into the 5- exo-trig, 5- exo-dig sequence, especially if a quaternary carbon centre is established during the first five-ring cyclization. The cascade allows construction of four and more chiral centres in a single convergent step. The influence of E/ Z geometry of the olefinic component is also evaluated.

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