INTERMEDIATE FOR SYNTHESIS OF A RING PART OF VITAMIN D DERIVATIVES HAVING A SUBSTITUENT AT 2-POSITION

摘要

The object of the present invention is to provide novel compounds corresponding to the A ring part of vitamin D derivatives having a substituent at the 2-position. According to the present invention, there are provided compounds of the general formula (1): (wherein R<1>, R<2> and R<3>, which may be the same or different, represent a hydrogen atom or a protecting group and R<4> represents a lower alkyl group), intermediates for synthesizing them and a process for preparing them.