Diastereoselective Synthesis of Galactopyranosyl Amino Esters and Their Transformation into C‐Nucleosides
摘要:
Galactopyranosylated olefinic ester (4) on conjugate addition of amines yielded stereoselectively galactopyranosylated amino esters (5-18) in fair to good yield. The selected amino esters (5, 6, 13, and 15-17) on reaction with isocyanates resulted in ureido galactopyranosyl amino esters (19-24) in very good yields. Lactamization of compounds 19-24 with DBU, 4 Angstrom MS, and tetrabutylammonium bromide in refluxing toluene gave respective C-galactopyranosyl dihydropyrimidine-2,4-diones (25-30) in respectable yields.