139400-25-2Relevant academic research and scientific papers
An effective method for the preparation of chiral polyoxy 8-membered ring enone corresponding to the B ring of taxol
Shiina,Shibata,Ibuka,Imai,Mukaiyama
, p. 113 - 122 (2001)
An effective method for the preparation of 8-membered ring enone, (4S,5R,7R,8R)-4,8-bis(benzyloxy)-7-(t-butyldimethylsiloxy)-5- (4-methoxybenzyloxy)-2,6,6-trimethylcyclooct-2-enone (1), in sufficient quantities was developed. Optically active trioxy aldehyde, (3R,4S)-4-benzyloxy-5-(t-butyldimethylsiloxy)-3-(4-methoxybenzyloxy)- 2,2-dimethylpentanal (3), was prepared first by diastereoselective dihydroxylation of (2R,4S)-2-(4-methoxyphenyl)-5,5-dimethyl-4-vinyl-1,3-dioxane derived from D-pantolactone. Next, 8-chloro-7-oxoaldehyde, (2R,3R,5R,6R)-2,6-bis(benzyloxy)-5-(t-butyldimethylsiloxy)-8-chloro-3- (4-methoxybenzyloxy)-4,4-dimethyl-7-oxononanal (30), was newly synthesized by the following reactions: i) MgBr2·OEt2-mediated diastereoselective aldol reaction of the aldehyde 3 with (Z)-2-benzyloxy-1-methoxy-1-(trimethylsiloxy)ethene and ii) reaction of methyl (2R,3R,5R,6S)-2,6-bis(benzyloxy)-3,7-bis(t-butyldimethylsiloxy)-5- (4-methoxybenzyloxy)-4,4-dimethylheptanoate with 1,1-dichloroethyllithium, followed by successive reductive dehalogenation of thus formed 1,1-dichloroethyl ketone with 1,1-dichloroethyllithium. Then, the chiral 8-chloro-7-oxoaldehyde 30 was converted to the 8-membered ring enone 1 by SmI2-mediated aldol cyclization.
Condensation of Ketene Acetals derived from Glycolates with Aldehydes and Ketones: Synthesis of α,β-Dialkoxy Esters
Gray, Brian D.,White, James D.
, p. 20 - 21 (1985)
Deprotonation of glycolate esters, followed by trapping with trimethylsilyl chloride, affords ketene acetal derivatives which undergo condensation (accompanied by silyl group transfer) with aldehydes and ketones in the presence of zinc chloride to give α,
