Removal of the 26-Methyl Group from 19-nor-1 alpha,25-Dihydroxyvitamin D-3 Markedly Reduces in Vivo Calcemic Activity without Altering in Vitro VDR Binding, HL-60 Cell Differentiation, and Transcription

[摘要]：Twelve new analogues of 19-nor-1 alpha,25-dihydroxyvitamin D-3 (5-16) were prepared by convergent syntheses, employing the Wittig-Horner reaction. The necessary Grundmann type ketones (45-48), possessing fixed configurations of the hydroxyl group at C-25, were obtained by a multistep procedure from commercial vitamin D-2 and enantiomers of 1,3-butanediol (23 and 24). We have examined the influence of removal of one of the methyl groups located at C-25 on the biological in vitro and in vivo activity. The in vivo tests showed that the synthesized vitamin D compounds (5-16) exhibit reduced calcemic activity both in bone and in the intestine. However, in vitro potency of 2-methylene and 2 alpha-methyl compounds (5-10, 13, and 14) remained similar or enhanced as compared to that of 1 alpha,25-(OH)(2)D-3.

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