| Popis: |
Alkylation of the lithio-demethylseleno-derivative of seleno-acetal 11 with chloromethyl isopropyl ether [shown by NMR to give the (22 S )-methylseleno-compound 13a as the major diastereoisomer] is the key reaction in the synthesis of the 24-oxa analogue (MC 1090, 8 ) of 1α-hydroxyvitamin D 3 ( 4 ). The metabolism of 8 to calcitroic acid ( 7 ) is demonstrated in vitro in a hepatocyte cell (Hep 3B) model. This supports the hypothesis that 8 can undergo enzymatic 25-hydroxylation analogous to the activation of 4 , or a similar side chain hydroxylation, but then short cuts the target cell side chain cleavage pathway taking 1α,25-dihydroxyvitamin D 3 to 7 . |
