Synthesis of 6,7-diaza-19-norvitamin D compounds

Two A-ring stereoisomeric 1-hydroxy-6,7-diaza-19-norvitamin D3 compounds 7a, 8a and their 25-hydroxylated analogs, 7c, 8c have been prepared starting with enantiomeric trans-3,5-dihydroxycyclohexanones 3c,d and the CD-ring 8-ketones 4a and 4c. 1,25-Dihydroxy azavitamins 7c and 8c are essentially devoid of biological activity, demonstrating the importance of the 5,7-diene structure of vitamin D.