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Cyclopentenone Annulation of 2‐Oxocycloalkane‐1‐carbonitriles
Author(s) -
Vassil I. Ognyanov,
Hesse Manfred
Publication year - 1987
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.19870700520
Subject(s) - chemistry , annulation , cyclopentenone , stereoselectivity , alkylation , pentadecane , bicyclic molecule , catalysis , sequence (biology) , base (topology) , stereochemistry , organic chemistry , medicinal chemistry , mathematical analysis , biochemistry , mathematics
Phase‐transfer alkylation of the 2‐oxocycloalkane‐l‐carbonitriles 1a and 1b with ethyl 4‐bromo‐3‐methoxy‐2‐butenoate ( 2 ), followed by deprotection and base‐catalyzed cyclization gave the annulated cyclopentenones 5a and 5b , respectively, in high overall yields ( Scheme 1 ). Stereoselective catalytic hydrogenation of 5b followed by de‐ethoxycarbonylation afforded 14‐oxo‐cis‐bicyclo[10.3.0]pentadecane‐l‐carbonitrile ( 7 ). Treatment of 7 with LiN(i‐Pr) 2 in THF gave the known synthetic muscone precursor 8 ( Scheme 2 ). The tricyclo[10.4.0.0 1,15 ]hexadecan‐14‐one ( 14 ) was prepared from 7 in 5 steps by a reaction sequence proceeding without affecting the chiral centres ( Scheme 2 ). The structure of 14 was established by X‐ray structure analysis ( Figure ).