Stereocontrolled synthesis of C10-C22 fragment of the immunosuppressant FK 506. An occurrence of complementary stereoselectivity in the C15 ketone reduction
stereocontrolled ester-enolate Claisenrearrangement of ene-ester 5, and the aldehyde 4 which was prepared from D-mannitol via anti selective methallylsilane addition to aldehyde 6 followed by modest stereoselective hydroboration based on 1,3-asymmetric induction. In the course of this reaction sequence a complementary stereoselection dependent on the used hydride reagents has occurred in reduction of the coupling