PURPOSE: To obtain the subject compd. useful for producing 7-O- glycosylrhodomycin in good yield by a simple method wherein a specific protective group is introduced into unprotected rhodomycinone aglicon to selectively alkylate a phenolic hydroxyl group.

CONSTITUTION: A compd. represented by formula I (wherein R1 and R3-R5 are each H; and R2 is OH or COOCH3) is reacted with 1,3-dichloro-1,1,3,3- tetraisopropyldisiloxane and, if necessary, subsequently reacted with tri-1-4C alkylsilyl halide to protect OH of OR4 and OR5 or, further, R2 and the obtained reaction product is alkylated to selectively alkylate OH of OR3 or, further, OR1 especially, OR3 to advantageously obtain the objective compd. represented by formula I (wherein R1 is H or 1-4C alkyl; R2 is OH, COOCH3 or a group represented by formula II; R3 is 1-4C alkyl; R4 and R5 are each H or combined to form tetraisopropyldisiloxane-1,3-diyl; and R5 is glycosyl) useful as an anti- tumor agent or its intermediate III (wherein R2 is OH or a group represented by formula II).