摘要:
The invention relates to precursors of the A-ring of vitamin D, of the formula (I): in which A, R, R1 and R2 are as defined in the specification. The invention also relates to a method of preparing compounds (I) comprising the enzymatic asymmetrization of 3,5-dihydroxybenzoic acid derivatives, as well as intermediates of preparation of said compounds.
摘要:
The invention relates to a method of preparing 1 .alpha.-hydroxyvitamin D or 1 .alpha.-hydroxy-previtamin D compounds by hydroxylating the 1 .alpha.-position of an adduct of a previtamin D compound with a suitable dienophile, in which adduct optionally present hydroxy group or hydroxy groups is or are protected, if desired, and after removal of the protecting group or groups, isolating the 1 .alpha.-hydroxyvitamin D or 1 .alpha.-hydroxy-previtamin D compound.The invention also relates to 1 .alpha.-hydroxy-previtamin D compounds.The invention further relates to an adduct of a previtamin D or tachysterol compound with a dienophile of the general formula ##STR1## in which A' and B' are equal and represent methoxy groups or ethoxy groups, or in which A' and B' together constitute a phenylimino or o-phenylene group.