Abstract: Optically active compounds of general formulae ##STR1## wherein A is O or S, R.sub.1 is a hydrogen atom, an alkyl group having 1-22 carbon atoms, a hydroxy containing alkyl group, para-alkyl substituted phenyl, para-alkyl substituted biphenyl, hydroxyphenyl, hydroxybiphenyl or tosyl; R.sub.2 is an alkyl group having 2-8 carbon atoms; m is an integer of 0-5, n is 0 or 1, where when m=0, n is not 1; p is 0 or 1; q is 0 or 1; D and E are independently H or a halogen atom; R.sub.3 is a linear alkyl group having 1 to 22 carbon atoms; and * and ** are asymmetric centers.