Synthesis of (1<i>α</i>)-1,25-Dihydroxyvitamin D<sub>3</sub>with a<i>β</i>-Positioned Seven-Carbon Side Chain at C(12)
作者:Diego M. Carballa、Antonio Rumbo、Mercedes Torneiro、Miguel Maestro、Antonio Mouriño
DOI:10.1002/hlca.201200427
日期:2012.10
A convergent synthesis of an analogue of (1α)‐1,25‐dihydroxyvitamin D3 (1b) with a C7 sidechain at C(12), i.e., of 5 (Fig.), is described. A key step of the synthesis is the assembly of the triene system by a PdII‐catalyzed ring closure of an enol triflate (‘bottom’ fragment) followed by coupling of the resulting PdII intermediate with an alkenylboronate (‘upper’ fragment) (Scheme 2). The synthetic