PURPOSE: To provide the titled compound useful in the fields of pharmaceuticals and agricultural chemicals, etc. as an antibiotic substance, carcinostatic agent, etc., economically in an industrial scale, by reacting a specific C-1 thiophosphinic acid ester of a sugar with a specific silyl ether.

CONSTITUTION: The objective compound is produced by reacting (A) a C-1 thiophosphinic acid ester derivative of a sugar wherein the H of the C-1 OH group of a sugar having hemiacetal bond at the C-1 position is substituted with the phosphinothioyl group of formula I [R1 and R2 are (substituted) alkyl or aryl] (preferably derivatives of C-1 dimethylthiophosphinic acid ester or C-1 diphenyl- thiophosphinic acid ester) with (B) a silyl ether obtained by substituting the H of the OH group of an alcohol selected from aliphatic alcohol, aromatic alcohol, steroid alcohol, glycerol derivative, and amino acid derivative with the silyl group of formula II (R3 is same as R1 and R2), preferably in the presence of silver perchlorate, at -10W+25°C.