The efficient and enantiospecific total synthesis of cyclopenta[b] phenanthrenes structurally-related to neurosteroids

Mingxing Qian, Douglas F. Covey

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

We report an efficient synthesis of cyclopenta[b]phenanthrenes functionalized at C-3 and C-8 from an optically pure Hajos-Parrish ketone. The key step is a neutral alumina-catalyzed Michael addition of a Hajos-Parrish ketone derivative (4) to 1,7-octadien-3-one (2) in 98% yield. This Michael addition product went through Krapcho decarbomethoxylation, aldol condensation, lithium liquid ammonia reduction, Wacker oxidation and acid-catalyzed cyclization to form cyclopenta[b]phenanthrene (1a) in 37% overall yield for the 7 steps.

Original languageEnglish
Pages (from-to)2057-2061
Number of pages5
JournalAdvanced Synthesis and Catalysis
Volume352
Issue number11-12
DOIs
StatePublished - Sep 13 2010

Keywords

  • Cyclopenta[b]phenanthrenes
  • Enantioselectivity
  • Hajos-Parrish ketone
  • Michael addition
  • Steroids
  • Total synthesis

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