Highly diastereoselective enolate addition of O-protected alpha-hydroxyacetate to (S(R))-tert-butanesulfinylimines: synthesis of taxol side chain.
The taxol side chain (S(R),2R,3S)-N-tert-butanesulfinyl-O-Boc-3-phenylisoserine benzyl ester 4c was synthesized through a lithium enolate addition of O-Boc-alpha-hydroxyacetate benzyl ester 5c to benzylidene (S(R))-tert-butanesulfinamide 6a in excellent yield and diastereoselectivity. By similar approach, a series of enantiopure 3-substituted isoserine benzyl esters 4 useful for the semi-syntheses of taxol derivatives were also prepared in high to excellent yields and diastereoselectivities. The diastereoselective addition mechanism was discussed on the basis of the experimental observation.
Wang
Yin
Y
Department of Chemistry of Medicinal Natural Products and Key Laboratory of Drug Targeting, West China School of Pharmacy, and National Key Laboratory of Biotherapy, Sichuan University, Chengdu 610041, PR China.
He
Qin-Fei
QF
Wang
Hao-Wei
HW
Zhou
Xuan
X
Huang
Zhi-Yan
ZY
Qin
Yong
Y
D001555:Benzene Derivatives / Q000138:chemical synthesis; D006016:Glycolates / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D017239:Paclitaxel / Q000138:chemical synthesis*; D013237:Stereoisomerism; D013457:Sulfur Compounds / Q000737:chemistry*
D001555:Benzene Derivatives; D006016:Glycolates; D007097:Imines; D013457:Sulfur Compounds; C031149:glycolic acid; D017239:Paclitaxel