LEWIS-ACID-CATALYSED ISOMERISATION OF BENZYLIDENE ACETALS OF METHYL α-L-RHAMNOPYRANOSIDE AND METHYL β-L-ARABINOPYRANOSIDE DERIVATIVES

Article abstract of DOI:10.1016/S0008-6215(00)80811-3

The Lewis-acid-catalysed isomerisation of several derivatives of methyl 2,3-O-benzylidene-α-L-rhamnopyranoside and methyl 3,4-O-benzylidene-β-L-arabinopyranoside has been investigated.The presence of equatorial substituents vicinal to the benzylidene ring decreases the rate of isomerisation, and exo isomers isomerise more quickly than the corresponding endo isomers.The occurence of isomerisation during the reductive cleavage reaction of acetal rings with LiAlH4-AlCl3 has been demonstrated.