NEW MATERIAL:The compound of formula I [R is H, CH3, CH2OH, OH, OCH2 Ph (Ph is phenyl), OCOCH3, OCH3, CH2OCH3, CH2OCPh3, CH2OCH2Ph, CH2 OCOCH3, NHCOCH3, >C(CH3)2 or >CHPh; R1 and R2 are (substituted) alkyl or aryl].

EXAMPLE: 2,3,4,6-Tetrabenzyl-α-D-glucopyranose dimethylthiophosphinic acid ester.

USE: Synthetic intermediate of glycoside compound useful in the fields of pharmaceuticals and agricultural chemicals, as antibiotic substance, carcinostatic agent, etc.

PREPARATION: A sugar having hemiacetal bond at C-1 position is made to react with a strong base such as n-butyl lithium, thallium ethoxide, etc., and then with the phosphonothioyl halide of formula II (X is halogen) preferably dimethylphosphonothioyl halide).