333972-99-9

Upstream product

• 53906-49-3 3β-ol-23,24-bisnor-chol-5-en-22-al hemihydrochloride 
• 333972-93-3 (S)-2-[(3S,8S,9S,10R,13S,14S,17R)-3-(tert-Butyl-diphenyl-silanyloxy)-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-17-yl]-propionaldehyde 
• 58479-61-1 tert-butylchlorodiphenylsilane 
• 107-30-2 chloromethyl methyl ether 
• 333972-95-5 (4R,5S)-5-[(3S,8S,9S,10R,13S,14S,17R)-3-(tert-Butyl-diphenyl-silanyloxy)-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-17-yl]-4-hydroxy-2-methylene-hexanoic acid ethyl ester 

Relevant academic research and scientific papers

Stereoselective synthesis of 24-alkyl-22-hydroxysterols based on chelation-controlled radical reactions

We have shown that the diastereoselectivity in the radical-mediated reactions of steroidal 24-methylene-22-oxy-25-oic acid esters 6-11 with alkyl iodides performed in the presence of Lewis acid MgBr2·OEt2 depends on the bulk of the alkyl iodides, the oxy groups at C-22 and the configuration at C-22. The ethylation of 9 afforded the syn-adduct exclusively and the methylation of 6 and 7, ethylation of 10 and isopropylation of 9 gave syn-adducts with high selectivities (syn-anti = 8.8-5.1 : 1). Other combinations, except for the tert-butyl radical addition to 6, 7 and 10 predominantly yielding anti-adducts, showed lower syn-selectivities.