Abstract: This invention relates to new optically active pyrimidinylphenyl ester compounds, having a liquid crystal phase of cholesteric and/or smectic C* phase, of the formula: ##STR1## wherein R* represents an optically-active alkyl group having an asymmetric carbon atom which is ##STR2## where R.sup.0 is a straight chain alkyl group of 2 to 6 carbon atoms, R.sup.1 is a straight chain alkyl group of 1 to 5 carbon atoms, R.sup.2 is a straight chain alkyl group of 1 to 2 carbon atoms, R.sup.3 is a straight chain alkyl group of 1 to 6 carbon atoms and n is 0 or 1, R presents a straight-chain alkyl group of 7 or 8 carbon atoms or a straight-chain alkoxy group of 7 or 8 carbon atoms and A represents ##STR3## or --O--.

Abstract: Ureylenethiophanes and their related compounds of the formula: ##SPC1##Having a cis-configuration on the ureylene or thioureylene juncture, which are useful as the intermediates in the synthesis of biologically active biotin and its related compounds, can be produced selectively by reacting the corresponding compounds of the formula: ##SPC2##With isocyanates or isothiocyanates wherein R is a hydrogen atom, an alkyl group or an aralkyl group, R.sub.1 and R.sub.2 are each a hydrogen atom or an aliphatic hydrocarbon group bearing or not a carboxyl group or any other group convertible thereto at the terminal position, X is a halogen atom, Y is an oxygen atom or a sulfur atom and Z is an oxygen atom, a sulfur atom, a sulfinyl group or a sulfonyl group.