Synthesis and spectroscopic studies of Novel type of unsaturated sugars

ABSTRACT

Reaction of carboethoxy acetonylidene triphenyl phosphorane [A] with aldehydo and keto sugars [la-d] led to the formation of the corresponding carboethoxy acetonylidene derivatives [2a-d], which constitute useful synthetic intermediates. Their spectroscopic data indicated the unique E configuration between the two olefinic protons and the presence of a keto enol equilibrium, in which the enolic structure stabilized by celation. Conversion of [2a] into a new type of 3 substituted coumarin [3] was established