A total synthesis of estrone based on a novel cascade of radical cyclizations.

ABSTRACT: Two conceptually different and novel radical-mediated cascade reactions leading to a total synthesis of the steroid (+/-)-estrone 1 and to a synthesis of 14-epiestrone 40 are described. Treatment of the iododienynone 23 with Bu(3)SnH/2,2'-azobis(isobutyronitrile) (AIBN) triggers a 13-endo-dig radical macrocyclization followed by two sequential radical transannulation reactions leading to the crystalline estrane 24 in 50% yield. The x-ray crystal structure of 24 established its trans, syn, stereochemistry. Transposition of the enone functionality in 24 next led to 38, which was then converted into 39 by reductive methylation. Deprotection of the methyl ether 39 finally gave 14-epiestone 40. When the substituted iodovinylcyclopropane 55 was treated similarly with Bu(3)SnH/AIBN, the resulting

SUBMITTER: Pattenden G 

PROVIDER: S-EPMC514428 | biostudies-literature | 2004 Aug

REPOSITORIES: biostudies-literature