TY - JOUR
T1 - 1,3-Allylic strain as a control element in the Paterno-Buchi reaction of chiral silyl enol ethers
T2 - Synthesis of diastereomerically pure oxetanes containing four contiguous stereogenic centers
AU - Bach, Thorsten
AU - Jödicke, Kai
AU - Kather, Kristian
AU - Fröhlich, Roland
PY - 1997/3/12
Y1 - 1997/3/12
N2 - The facial diastereoselectivity in the Paterno-Buchi reaction of chiral silyl enol ethers and benzaldehyde was studied. The substituents (R(S),R(L)) at the stereogenic carbon atom (-C*HR(S)R(L)) attached to the β-position of the silyl enol ether were varied in order to evaluate the influence of steric bulk and electronic effects. The combined yields for the two diastereomeric 3-(silyloxy)oxetanes a and b range between 44% and 76%. In accordance with the 1,3-allylic strain model the facial diastereoselectivity (diastereomeric ratio (dr) = a/b) was best with large (R(L) = t-Bu, SiMe2Ph) and polar (R(L) = OMe) substituents at the γ-position of the silyl enol ether (dr up to > 95/5). Two regioselective ring opening reactions were applied to the product oxetanes 29a, 50, and 51. They furnished diastereomerically pure diols (52, 53) and triols (31) in excellent yields.
AB - The facial diastereoselectivity in the Paterno-Buchi reaction of chiral silyl enol ethers and benzaldehyde was studied. The substituents (R(S),R(L)) at the stereogenic carbon atom (-C*HR(S)R(L)) attached to the β-position of the silyl enol ether were varied in order to evaluate the influence of steric bulk and electronic effects. The combined yields for the two diastereomeric 3-(silyloxy)oxetanes a and b range between 44% and 76%. In accordance with the 1,3-allylic strain model the facial diastereoselectivity (diastereomeric ratio (dr) = a/b) was best with large (R(L) = t-Bu, SiMe2Ph) and polar (R(L) = OMe) substituents at the γ-position of the silyl enol ether (dr up to > 95/5). Two regioselective ring opening reactions were applied to the product oxetanes 29a, 50, and 51. They furnished diastereomerically pure diols (52, 53) and triols (31) in excellent yields.
UR - http://www.scopus.com/inward/record.url?scp=1842368466&partnerID=8YFLogxK
U2 - 10.1021/ja963827v
DO - 10.1021/ja963827v
M3 - Article
AN - SCOPUS:1842368466
SN - 0002-7863
VL - 119
SP - 2437
EP - 2445
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 10
ER -