34 research outputs found
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