Hydroxy-16α,17α,21-trimethyl-5-en-20-one was synthesized from 3α-acetoxypregna-5,16-dien-20-one and characterized by elemental analysis, 1H NMR, MS and IR. 16α,17α-Dimethyl steroid was formed by treatment of 3β-...Hydroxy-16α,17α,21-trimethyl-5-en-20-one was synthesized from 3α-acetoxypregna-5,16-dien-20-one and characterized by elemental analysis, 1H NMR, MS and IR. 16α,17α-Dimethyl steroid was formed by treatment of 3β-acetoxypregna-5,16-dien-20-one with methylmagnesium bromide, followed by reaction of the resulting 17(20)-enolate with methyl iodide. The main by- products were 3β-hydroxy-16α,17α-dimethyl-5-en-20-one. LHDMS([(CH 3) 3Si] 2NLi) and LDA([(CH 3) 2CH] 2NLi) were chosen as proper reagents for 21-position alkylation. The almost quantitative conversion of 16α,17α-dimethyl corticosteroid was achieved and the highest yield of the 16α,17α,21-trimethyl corticosteroid was 78%. The optimum reaction temperature was -20 ℃ for 16α,17α- dialkylation and was -50 ℃ for 21- position alkylation.展开更多
Using an available compound 3 pentanone(1) as starting material, the key intermediate compound 4,6 dimethyl 3,7 nonandione(5) was synthesized through the addition elimination of silylenol ether and Michael addition of...Using an available compound 3 pentanone(1) as starting material, the key intermediate compound 4,6 dimethyl 3,7 nonandione(5) was synthesized through the addition elimination of silylenol ether and Michael addition of α methylene 3 pentanone(4) with silylenol ether(2). In the presence of chiral reagent 6 β phenyl amino 3 β,5α chlorestandiol(7), compound (5) was reduced by KBH 4 directly to give Tobacco Beetle Pheromone (7S) (-) 4,6 dimethyl 7 hydroxyl 3 nonanone(6). 25 D=-35 87°( c =0 23, CHCl 3), overall yield 23 9%.展开更多
文摘Hydroxy-16α,17α,21-trimethyl-5-en-20-one was synthesized from 3α-acetoxypregna-5,16-dien-20-one and characterized by elemental analysis, 1H NMR, MS and IR. 16α,17α-Dimethyl steroid was formed by treatment of 3β-acetoxypregna-5,16-dien-20-one with methylmagnesium bromide, followed by reaction of the resulting 17(20)-enolate with methyl iodide. The main by- products were 3β-hydroxy-16α,17α-dimethyl-5-en-20-one. LHDMS([(CH 3) 3Si] 2NLi) and LDA([(CH 3) 2CH] 2NLi) were chosen as proper reagents for 21-position alkylation. The almost quantitative conversion of 16α,17α-dimethyl corticosteroid was achieved and the highest yield of the 16α,17α,21-trimethyl corticosteroid was 78%. The optimum reaction temperature was -20 ℃ for 16α,17α- dialkylation and was -50 ℃ for 21- position alkylation.
文摘Using an available compound 3 pentanone(1) as starting material, the key intermediate compound 4,6 dimethyl 3,7 nonandione(5) was synthesized through the addition elimination of silylenol ether and Michael addition of α methylene 3 pentanone(4) with silylenol ether(2). In the presence of chiral reagent 6 β phenyl amino 3 β,5α chlorestandiol(7), compound (5) was reduced by KBH 4 directly to give Tobacco Beetle Pheromone (7S) (-) 4,6 dimethyl 7 hydroxyl 3 nonanone(6). 25 D=-35 87°( c =0 23, CHCl 3), overall yield 23 9%.
