AMPHIPHILIC CARBOHYDRATE-BASED MESOGENS .9. MESOGENIC 4-O-ALKYL-D-GLUCOSES VIA METHYL 4,6-O-ALKYLIDENE-D-GLUCOPYRANOSIDES

The 4,6-O-alkylidene derivatives (hexylidene-decylidene, 2a-e) are pre pared by condensation of methyl alpha- or beta-D-glucopyranoside 1 wit h alkanals in the presence of pyridinium tosylate. O-diethylborylation of 2 gives 3 which are allowed to react firstly with bromodiethylbora ne and subsequently with sodium triethylhydroborate to yield methyl 4- O-alkyl-D-glucopyranosides 5 after deborylation. Acid hydrolysis of 5 gives mesogenic 4-O-alkyl-D-glucopyranoses 6a-e. The amphiphilic 6 exh ibit the smectic A liquid crystalline phase on melting.