Synthesis of a chiral steroid ring D precursor starting from carvone

A chiral five-membered, silyl enol ether containing, steroid ring D precursor has been synthesized front carvone. This silyl enol ether has been applied in the synthesis of a chiral C17 functionalized steroid skeleton using the addition of a carbocation, generated with ZnBr2 from a Torgov reagent, followed by cyclization of the adduct by treatment with acid

(3R,5S,6S,8R,10S)-8-Acetyl-7-hydroxy-3-isopropenyl-10-methylperhydrophenanthren-1-one

In the crystal structure of the title compound, C20H30O3, there is an intramolecular hydrogen bond between the hydroxyl and acetyl groups [O...O = 2.722 (3) A

17-Isopropyl-3-methoxy-13-methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthrene

The steroid ring B of the title compound, C22H32O, is in a half-chair conformation. The five-membered ring is in an intermediate form between the envelope and half-chair conformation

Domino Mukaiyama-Michael reactions in the synthesis of polycyclic systems

Good results were obtained in the Mukaiyama-Michael reaction of the silyl enol ether of cyclohexanone with 2-methyl-2cyclopentenone and carvone, with transfer of the silyl group to the receiving enone and with TrSbCl6 as catalyst. A second Mukaiyama-Michael reaction of this new silyl enol ether with methyl vinyl ketone and cyclization of the resulting adduct leads to tricyclic compounds in one-pot domino sequences. The scope and limitations of this domino reaction have been investigated

1-phenylthio-3-vinyl-3-cyclohexenol, a new reagent for bis-annelation of silyl enol ethers

1-Phenylthio-3-vinyl-cyclohex-1-en-3-ol (2) has been synthesized and investigated as a new bis-annelation reagent for silyl enol ethers. Reagent 2 can be synthesized by a Grignard reaction of vinyl magnesium bromide with 3-phenylthiocyclohexenone. The reaction with silyl cool ethers takes place Under Lewis acid catalysis and generally proceeds in good yields. The resulting phenylthiodienes can be hydrolyzed to enones, which have been cyclized in a homologous aldol reaction to polycyclic compounds

A new approach toward the synthesis of C,D-cis coupled steroid and C,D-cis coupled D-homosteroid skeletons

A short and efficient procedure has been developed for the synthesis of C,D-cis coupled steroid and D-homo steroid skeletons. A Mukaiyama reaction with transfer of the silyl group of the starting silyl enol ether to the enol of the adduct followed by addition of vinyl magnesium bromide to the unprotected carbonyl group leads to adducts which can be cyclized with ZnBr2. The synthesis of functionalized steroid skeletons in overall yields of about 50% in four steps can be achieved in this way. (C) 2003 Elsevier Science Ltd. All rights reserved