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The Efficient and Enantiospecific Total Synthesis of Cyclopenta[ b ]phenanthrenes Structurally‐Related to Neurosteroids
Author(s) -
Qian Mingxing,
Covey Douglas F.
Publication year - 2010
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201000370
Subject(s) - chemistry , ketone , phenanthrenes , yield (engineering) , aldol condensation , aldol reaction , total synthesis , organic chemistry , phenanthrene , catalysis , enantioselective synthesis , stereochemistry , medicinal chemistry , materials science , metallurgy
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.
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