Olefin Preparation via Palladium-Catalyzed Oxidative De-Azotative and De-Sulfitative Internal Cross-Coupling of Sulfonylhydrazones.

A novel reactivity of sulfonylhydrazones under Pd catalysis is described, where SO2 and N2 are formally extruded to afford the product of an apparent internal coupling reaction. The reaction is effective with both carbocyclic and heterocyclic aromatic precursors.

Stereoselective C-glycosylation reactions with arylzinc reagents.

A general, transition-metal-free, highly stereoselective cross-coupling reaction between glycosyl bromides and various arylzinc reagents leading to ß-arylated glycosides is reported. The stereoselectivity of the reaction is explained by invoking anchimeric assistance via a bicyclic intermediate. Stereochemical probes confirm the participation of the 2-pivaloyloxy group. Finally, this new method was applied to a short and efficient stereoselective synthesis of Dapagliflozin and Canagliflozin.

Practical synthesis of (2'R)-2'-deoxy-2'-C-methyluridine by highly diastereoselective homogeneous hydrogenation.

Diastereoselective hydrogenation of 2'-deoxy-2'-exo-methyleneuridine was carried out under homogeneous conditions using a low loading of a chiral Rh catalyst. This, coupled with improvements in the synthesis of the substrate, allowed the smooth pilot plant preparation of the title compound on >10 kg scale.

Regioselective cross-coupling reactions of boronic acids with dihalo heterocycles.

The carboxylic acid anion moiety has been used as a tunable directing group in the cross-coupling reaction of 2,6-dichloronicotinic acid and 2,5-dibromo-1,2,4-triazole derivatives producing selectively the 2- or 6-substituted nicotinic acids, while only the 5-substituted triazoles were obtained under a variety of conditions.

Carboxylate directed cross-coupling reactions in the synthesis of trisubstituted benzoic acids.

The carboxylate anion has been used as a directing group to effect selective ortho-substituted derivatives 3 (>99:1 selectivity 50-80% yield). The solvent, base, and equivalents of base are the determining factors for the success of this reaction. The directing effect can be reversed by the appropriate use of phosphine ligands to prepare the para-substituted 4 selectively (ca. 12:1 selectivity).

Copper-catalyzed tethered aziridination of unsaturated N-tosyloxy carbamates.

Aziridines were formed by copper-catalyzed intramolecular nitrene addition to alkenes. The carbamate group was used as the tether between the alkene and the nitrene. Subsequent nucleophilic attack of the aziridine was accomplished using RSH, R2NH, N3-, or ROH as the nucleophile. This addition was found to be regio- and stereoselective. This methodology has been used to demonstrate its utility in the regio- and stereoselective synthesis of a 1,2-diamino-3-hydroxycyclohexane. This substitution pattern is found in natural products such as Tamiflu.