N-Trifluoroacetyl-L-acosamine (18) has been chirally synthesised from the chiral educt (1) obtained from cinnamaldehyde and bakers' yeast, whereas N-trifluoroacetyl-L-daunosamine (17) was obtained by inverting the configuration at C-4 of the intermediate δ-lactone (11); compounds (18) and (17) have also been prepared from L-threonine via the δ- and γ-lactones (14) and (9), by inverting the configuration
Stereocontrol in radical Mannich equivalents for aminosugar synthesis: haloacetal and 2-(phenylthio)vinyl tethered radical additions to α-hydroxyhydrazones
作者:Gregory K. Friestad、Tao Jiang、Gina M. Fioroni
DOI:10.1016/j.tet.2008.10.013
日期:2008.12
silicon-tethered ethynyl group to the CN bond of hydrazones, affording anti-hydrazino alcohols with a trans-2-(phenylthio)vinyl substituent. The one-pot process occurs under neutral, tin-free radical conditions, and offers stereocontrol which is complementary to the haloacetal method. Synthetic utility of the radical Mannich concept is demonstrated in a brief asymmetric synthesis of N-trifluoroacetyl-l-daunosamine