LE><IMG SRC="/isubscribe/journals/joceah/72/i14/figures/jo070685mn00001.gif" ALIGN="left" HSPACE=5> |
1
lpha.gif" BORDER=0>,25-Dihydroxyvitamin D
3 (ca
lcitrio
l,
1) is a bioregu
lator important for the treatment of various humanmetabo
lic diseases and biomedica
l research. Herein, we report an efficient diastereose
lective approachto the key
trans-hydrindane bui
lding b
lock for ca
lcitrio
l synthesis (
2a) starting from the readi
ly accessib
leoptica
lly active tetrahydroindenedione derivative (Hajos dione,
3). It was found that epoxide ring openingin a re
lated hydroxy epoxide (
7) with sodium cyanoborohydride-BF
3 × Et
2O occurs by hydride anionaddition at the ring juncture position to produce a vicina
l dio
l with the
trans-hydrindane ring system(
6a). Four methods for se
lective deoxygenation of the sterica
lly
less shie
lded hydroxy group in dio
l 6awere examined with an approach based on a cyc
lic su
lfate of the dio
l as the most efficient and operationa
llyconvenient method.