d-Gulonolactone as a Synthon for l-Noviose: First Preparation of 4-<i>O</i>-Demethyl-l-noviofuranose and Related Derivatives^†

A new synthesis of l-noviose (11), a sugar moiety of novobiocin, is presented. d-Gulonolactone was initially converted in a few steps to the key ester derivative 7 [1-O-benzyl methyl 2,3-O-(1-methylethylidene)-α-l-lyxofuranosiduronate]. An appropriate selection of protecting groups enabled transformation of 7 under mild reaction conditions to 4-O-demethyl-l-noviofuranose 9a and related 9b−c. Derivatives 9 were further converted either to l-lyxopyranoses (10a and 10b) or to methyl l-lyxofuranoside 12.