Glycals were found to react with a reagent system comprising of phenyliodine bis(trifluoroacetate) (PIFA) and Me 3 SiN 3 in the presence of TMSOTf as a catalyst to form the corresponding vicinal 1,2-diazides. On the other hand, they reacted with another reagent system phenyliodine diacetate (PIDA) and Me 3 SiN 3 , also in the presence of TMSOTf as a catalyst, to lead to the corresponding vicinal 1,2-azidoacetates. These azido derivatives were converted into a number of 2-azido-N-glycopeptides, pseudotrisaccharides, and a piperidine triol derivative, an iminosugar.Scheme 2 Percentage yield and a/b ratio of the 1,2-diazides.Scheme 3 Proposed mechanism for the formation of 1,2-diazides. This journal isScheme 6 Reaction of glycal derivatives 1, 8b and 29 with PIDA-Me 3 SiN 3 .Scheme 7 Proposed mechanisms for the reaction of glycals with PIDA and Me 3 SiN 3 .This journal is

An unprecedented water-mediated and TEMPO-catalyzed, one-step, highly regiospecific and stereoselective functionalization of glycals to 2-azido-2-deoxysugars has been developed using a PIFA-MeSiN reagent system in the presence of BuNHSO as a phase-transfer catalyst. The method is metal-free, proceeds under mild reaction conditions, and tolerates a variety of protecting groups. Using this method, the synthesis of an important trisaccharide unit bound by the monoclonal anti-I Ma antibody has also been demonstrated.

A concise stereoselective synthesis of an imino glycal is described in 8 steps starting from 1,2‐anhydro‐3,4,6‐tri‐O‐benzyl‐d‐glucopyranose. The utility of the imino glycal has been demonstrated in synthesis of (–)‐1‐epi‐adenophorine and a homoiminosugar as a glycosidase inhibitor. The important features of the developed route include high yields, high stereoselectivity, and application in the synthesis of other iminosugars. Additionally, a new synthon 2‐nitro‐imino glycal has also been synthesized which could act as valuable synthon in carbohydrate chemistry.

A simple, highly efficient and regiospecific method for the direct conversion of 3- O-benzylated as well as silylated glycals into the corresponding enones has been developed using PIFA-TEMPO and water reagent system. The reaction is scalable on a gram scale under mild conditions with a yield up to 86%.

No abstract