Synthesis and mesomorphic behaviour of lithocholic acid derivatives

A series of liquid crystalline derivatives of lithocholic acid were prepared using simple chemical reactions involving the terminal functional group-hydroxyl at C-3 and/or carboxyl at C-24. Thus methyl -3-(3-carboxy propionyl) lithocholate (I), 3-(3-carboxy propionyl) lithocholic acid (II), 3-acetyl lithocholic acid (III), 3-propionyl lithocholic acid (IV), 3-benzoyl lithocholic acid (V), 3-(4-nitrobenzoyl) lithocholic acid (VI), 3-cinnamoyl lithocholic acid (VII), methyl-3-(4-nitrobenzoyl) lithocholate (VIII) and 1,4-bis [cholan-24-methoxy carbonyl-3-oxycarbonyl] butane (IX) were prepared in good yields and characterized by IR, NMR and polarizing optical microscopy. Compounds (I) and (IX) exhibited monotropic behaviour while the others were enantiotropic. Some of the compounds also showed a high tendency of super cooling. Compounds (V), (VI) and (IX) formed cholesteric phase while the remaining compounds displayed smectic phase.