Efficient C-21 deoxygenation of 21-alkoxy-20-keto corticoid steroids with trimethylsilyl iodide in the presence of methanol
摘要:
Reaction of 21-alkyl ethers 1, 4-6, 8, and 9 with a large excess of trimethylsilyl iodide (TMSI) produced the deoxygenated products 3 and 11 in low to moderate yields along with a small amount of 21-alcohols 2 and 10. The deoxygenation reaction in the presence of 1.5 molar equiv of MeOH gave the products in much higher yields than those without MeOH, except the reaction of the ethyl and n-propyl ethers 4 and 5. Treatment of 1 and 8 with trimethylsilyl chloride/NaI in the presence of MeOH gave similar results to those with TMSI. Compound 3 was also produced in high yields by reaction of 1 and 4 with HI under mild conditions. On the other hand, treatment of 17-alpha-ketol 7 with TMSI in the presence of MeOH yielded 17-alpha-beta-methyl D-homo steroid 15. The results along with deuterium-labeling experiments with MeOD and IR and H-1 NMR spectral analysis during the reaction with TMSI suggest that dealkylation of the 21-alkyl ethers precedes the deoxygenation, in which HI produced in situ by reaction of MeOH with TMSI would be involved.
Nouveaux dérivés 17,20-époxydes du pregnane, leur application à la préparation de dérivés cortisoniques et intermédiaires
申请人:ROUSSEL UCLAF
公开号:EP0607088A1
公开(公告)日:1994-07-20
L'invention concerne les composés (I) :
R = oxo ou β-OH et A et B représentent un reste 3-céto Δ4 ou Δ1,4 libre ou protégé, leur préparation, leur application à la préparation des composés (A) :
R₃ est un groupement protecteur du radical hydroxy, ainsi que des intermédiaires.