An improved route to PUGNAc and its galacto-configured congener

Phosphine-Catalyzed Intramolecular Cyclizations of α-Nitroethylallenoates Forming (Z)-Furanone Oximes

A novel and efficient phosphine-catalyzed intramolecular cyclization of α-nitroethylallenic esters is reported. This process appears to be practical for the stereoselective syntheses of (Z)-furan-2(3H)-one oxime derivatives in excellent yields. Mechanistically, the reaction involves a phosphine-catalyzed Michael addition of an alkylideneazinate and rearrangement of the cyclic nitronate to the α-nitrosodihydrofuran.

Elevation of Global O-GlcNAc in rodents using a selective O-GlcNAcase inhibitor does not cause insulin resistance or perturb glucohomeostasis

The O-GlcNAc modification is proposed to be a nutrient sensor with studies suggesting that global increases in O-GlcNAc levels cause insulin resistance and impaired glucohomeostasis. We address this hypothesis by using a potent and selective inhibitor of O-GlcNAcase, known as NButGT, in a series of in vivo studies. Treatment of rats and mice with NButGT, for various time regimens and doses, dramatically increases O-GlcNAc levels throughout all tissues but does not perturb insulin sensitivity or alter glucohomeostasis. NButGT also does not affect the severity or onset of insulin resistance induced by a high-fat diet. These results suggest that pharmacological increases in global O-GlcNAc levels do not cause insulin resistance nor do they appear to disrupt glucohomeostasis. Therefore, the protective benefits of elevated O-GlcNAc levels may be achieved without deleteriously affecting glucohomeostasis.