De novo synthesis of carbohydrates by stereoselective aldol reaction: L-cladinose.
Aldol reactions of methyl 2-methoxypropanoate (4), the corresponding ester of 2-methoxypropanoic acid with 4-methyl-2,6-di-(tert-butyl)phenol (13), and silylketene acetals 14 and 15 with (S)-2-(phenyl-methoxy)propanal (17) have been investigated. The lithium enolate of 4 reacts with 17 to give primarily beta-hydroxy ester 18a. If the reaction is carried out with the bis-silylketene acetal 14 under the influence of stannic chloride, beta-hydroxy acid 20c is produced. Compound 20c is cleanly inverted, via the beta-lactone 26, to provide beta-hydroxy acid 19c. Compound 18a has been converted into L-cladinose by the sequence of steps: 18a----35----39----40----41----42----1.
Montgomery
S H
SH
Department of Chemistry, University of California, Berkeley 94720.
Pirrung
M C
MC
Heathcock
C H
CH
D055598:Chemical Phenomena; D002621:Chemistry; D006601:Hexoses / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D008722:Methods; D015394:Molecular Structure; D013237:Stereoisomerism
D006601:Hexoses; C013889:cladinose