For the first time 1,3-dioxalane and 1,3-oxathiolane derivatives containing hydroxymethyl and halomethyl groups have been synthesized, their isomers isolated by chromatographic method. The configurational structures sis-, and trans- isomers of ((S,R)- (4-(bromomethyl)-1,3-dioxolan-2-yl)-(3a,b), ((S,R)- (5-(chloromethyl)-1,3-oxathiolan-2-yl)methyl benzoates (5a,b) have been completely assigned by 500 MHz 1H COSY NMR spectroscopy.