Application of Ugi reactions in synthesis of divalent neoglycoconjugates: Evidence that the sugars are presented in restricted conformation

[GRAPHICS] The Ugi reaction has been used to prepare divalent galactose derivatives. N MR analysis shows that a divalent neoglycoconjugate, where the glycopeptide s are bridged by a terephthaloyl group, is an 83:17 mixture of two conforme rs; the amide groups of the major isomer have E-anti conformations. The spa tial relationship and the relative orientation of the sugars are restricted , which may have consequences for the recognition of this and related struc tures in biological systems.