Synthesis of glycosyl chlorides using catalytic Appel conditions

The stereoselective synthesis of glycosyl chlorides using catalytic Appel conditions is described. Good yields of α-glycosyl chlorides were obtained using a range of glycosyl hemiacetals, oxalyl chloride and 5 mol% Ph3PO. For 2-deoxysugars treatment of the corresponding hemiacetals with oxalyl chloride without phosphine oxide catalyst also gave good yields of glycosyl chloride. The method is operationaly simple and the 5 mol% phosphine oxide by-product can be removed easily. Alternatively a one-pot, multi-catalyst glycosylation can be carried out to transform the glycosyl hemiacetal directly to a glycoside

Synthesis of Pyridylsulfonium Salts and their Application in Transition Metal-Free Formation of Functionalized Bipyridines

An S-selective arylation of pyridylsulfides with good functional group tolerance has been developed. The resulting pyridylsulfonium salts have been used in a scalable transition metal-free coupling protocol yielding functionalized bipyridine scaffolds with extensive functional group tolerance and modularity. Pyridylsulfonium salts were coupled to lithiated pyridines in a sulfur-mediated synthesis of bipyridines. This modular methodology, permits selective introduction of functional groups from commercially available pyridyl halides, furnishing symmetrical and unsymmetrical 2,2’- and 2,3’-bipyridines. Iterative application of the methodology enabled the synthesis of a functionalized terpyridine with three different pyridine components