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The Enantioselective Synthesis of 3‐Methoxy‐1, 3, 5 (10)‐estratrien‐11, 17‐dione by a Thermal Intramolecular Cycloaddition Reaction . Preliminary communication
Author(s) -
Oppolzer Wolfgang,
Bättig Kurt,
Petrzilka Martin
Publication year - 1978
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19780610535
Subject(s) - chemistry , intramolecular force , cycloaddition , enantioselective synthesis , benzocyclobutene , stereochemistry , salt (chemistry) , medicinal chemistry , intramolecular reaction , organic chemistry , catalysis , polymer
The enantiomerically pure (+)‐3‐methoxy‐1, 3, 5 (10)‐estratrien‐11, 17‐dione 11 (with trans‐anti‐trans configuration) was synthesized in a highly stereocontrolled fashion from (±)‐ t ‐butyl 4‐methoxy‐1‐benzocyclobutene carboxylate (8) and the (+)‐carboxylic acid 6 , obtained from 4 in two steps, followed by one crystallization of the (+)‐ephedrine salt. The key step 10→11 (Scheme 2) involves a thermal intramolecular cycloaddition reaction.