Chemical synthesis and immunosuppressive activity of dipalmitoyl phosphatidylinositol hexamannoside.

Phosphatidylinositol mannosides (PIMs) isolated from mycobacteria have been identified as an important class of phosphoglycolipids with significant immune-modulating properties. We present here the synthesis of dipalmitoyl phosphatidylinositol hexamannoside (PIM(6)) 1 and the first reported functional biology of a synthetic PIM(6). Key steps in the synthetic protocol included the selective glycosylation of an inositol 2,6-diol with a suitably protected mannosyl donor and construction of the glycan core utilizing a [3 + 4] thio-glycosylation strategy.

Highly (E)-selective Wadsworth-Emmons reactions promoted by methylmagnesium bromide.

An experimentally simple protocol for the very highly (E)-selective Wadsworth-Emmons reaction [(E):(Z) selectivities in excess of 180:1 in some cases] of a range of straight-chain and branched aliphatic, substituted aromatic, and base-sensitive aldehydes via reaction with an alkyl diethylphosphonoacetate and MeMgBr is reported.

Asymmetric synthesis of 3,4-anti- and 3,4-syn-substituted aminopyrrolidines via lithium amide conjugate addition.

The diastereoselective conjugate addition of homochiral lithium amides to methyl 4-(N-allyl-N-benzylamino)but-2-enoate has been used as the key step in a simple and efficient protocol for the preparation of 3,4-substituted aminopyrrolidines. This protocol provides a complementary and stereoselective route to both anti- and syn-3-amino-4-alkylpyrrolidines as well as anti- and syn-3-hydroxy-4-aminopyrrolidines, in high de and ee viabeta-amino enolate functionalisation. This methodology has been applied to the synthesis of anti-(3S,4S)- and syn-(3R,4S)-3-methoxy-4-(N-methylamino)pyrrolidine.

Inhibition of cobalamin-dependent methionine synthase by substituted benzo-fused heterocycles.

The cobalamin-dependent cytosolic enzyme, methionine synthase (EC.2.1.

An improved method for Lewis acid catalyzed phosphoryl transfer with Ti(t-BuO)4.

Several inorganic esters have been evaluated as phosphoryl transfer catalysts. Of these, Ti(t-BuO)(4) was found to be the most effective catalyst giving excellent yields of the desired phosphate esters. The loading of the catalyst could be reduced to a little as 5 mol % for a majority of substrates with no loss in the yield of product.