PROBLEM TO BE SOLVED: To obtain the subject new compound, having high vitamin D receptor- binding activities and useful as a calcium metabolism improver.
SOLUTION: This compound is represented by formula I (R1, R2 and R3 are each H or a protecting group of OH; R4 is a 2-6C lower alkyl), e.g. (23Z)-(20 S,22S)-1α,3β-bis(methoxycarbonyloxy)-22-ethyl-25-(methoxymethoxy)-24- trimethylsilyloxychloesta-5,7,23-triene. The compound represented by formula I is obtained by passing a cholesta-5,7,22-trien-24-one derivative represented by formula II as a starting raw material through 4 steps such as reduction, converting the raw material into 20-epi-22(R)-lower alkylprevitamin D derivative represented by formula III, then thermally isomerizing the resultant derivative and subsequently as necessary, deprotecting the prepared compound. The compound is useful for treating deficiency in calcium methaboilism such as hypoparathyroidism, hyperparathyroidism, osteomalacia or iosteroporosis, dermatoses such as psoriasis or diseases caused by cell differentiation function anomaly such as malignant tumor, e.g. myelogenic leukemia or mammary cancer.