Convenient preparation of L-arabino-hexos-5-ulose derivatives from lactose.
2,6-di-O-benzyl- (9), 2-O-benzyl-3,4-O-isopropylidene- (19), and 2-O-benzyl-6-O-m-chlorobenzoyl-L-arabino-hexos-5-ulose (20) have been prepared using 4'-deoxy-4'-eno- and 6'-deoxy-5'-eno lactose dimethyl acetal derivatives 7 and 14 as key intermediates. The synthesis of enol ethers 7 and 14 has been performed with good yields by base-promoted elimination of acetone or p-toluenesulfonic acid from 2',6'-di-O-benzyl-, and 6'-O-p-toluenesulfonyl-2,3:5,6:3',4'-tri-O-isopropylidenelactose dimethyl acetal, respectively. The epoxidation with MCPBA of 7 and 14 in methanol or dichloromethane furnishes C-5'-methoxy and C-5'-m-chlorobenzoyloxy derivatives, easily transformed with good yields into L-arabino 5-ketoaldohexoses 9, 19 and 20.
Dipartimento di Chimica Bioorganica e Biofarmacia, Università di Pisa, Via Bonanno 33, I-56126, Pisa, Italy. giocate@farm.unipi.it
Giorgio
G
Catelani
Antonino
A
Corsaro
Felicia
F
D'Andrea
Manuela
M
Mariani
Venerando
V
Pistarà
Elisa
E
Vittorino
D002724:Chlorobutanol; D002855:Chromatography, Thin Layer; D007661:Ketoses / Q000138:chemical synthesis* / Q000737:chemistry*; D007785:Lactose / Q000031:analogs & derivatives / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure
D007661:Ketoses; C017022:glucosone; D002724:Chlorobutanol; D007785:Lactose