Substituted thieno[2,3-d]pyrimidines as adenosine A2A receptor antagonists.

A novel series of benzyl substituted thieno[2,3-d]pyrimidines were identified as potent A2A receptor antagonists. Several five- and six-membered heterocyclic replacements for the optimized methylfuran were explored. Select compounds effectively reverse catalepsy in mice when dosed orally.

Design and characterization of optimized adenosine A2A/A1 receptor antagonists for the treatment of Parkinson's disease.

The design and characterization of two, dual adenosine A(2A)/A(1) receptor antagonists in several animal models of Parkinson's disease is described. Compound 1 was previously reported as a potential treatment for Parkinson's disease. Further characterization of 1 revealed that it was metabolized to reactive intermediates that caused the genotoxicity of 1 in the Ames and mouse lymphoma L51784 assays. The identification of the metabolites enabled the preparation of two optimized compounds 13 and 14 that were devoid of the metabolic liabilities associated with 1. Compounds 13 and 14 are potent dual A(2A)/A(1) receptor antagonists that have excellent activity, after oral administration, across a number of animal models of Parkinson's disease including mouse and rat models of haloperidol-induced catalepsy, mouse and rat models of reserpine-induced akinesia, and the rat 6-hydroxydopamine (6-OHDA) lesion model of drug-induced rotation.

Optimization of arylindenopyrimidines as potent adenosine A(2A)/A(1) antagonists.

Two reactive metabolites were identified in vivo for the dual A(2A)/A(1) receptor antagonist 1. Two strategies were implemented to successfully mitigate the metabolic liabilities associated with 1. Optimization of the arylindenopyrimidines led to a number of amide, ether, and amino analogs having comparable in vitro and in vivo activity.

Enantioselective total synthesis of (+)-obtusenyne.

A total synthesis of the laurencia metabolite (+)-obtusenyne has been completed. The key steps include a Sharpless kinetic resolution and an asymmetric glycolate alkylation to establish the stereogenic centers adjacent to the ether linkage and a ring-closing metathesis reaction to construct the nine-membered ether without the aid of a cyclic conformational constraint. The synthesis was completed in 20 linear steps from commercially available 1,5-hexadiene-3-ol.

Optically active iridium imidazol-2-ylidene-oxazoline complexes: preparation and use in asymmetric hydrogenation of arylalkenes.

This work explores the potential of iridium complexes of the N-heterocyclic carbene oxazoline ligands 1 in asymmetric hydrogenations of arylalkenes. The accessible carbene precursors, imidazolium salts 2, and robust iridium complexes 5 facilitated a discovery/optimization approach that featured preparation of a small library of iridium complexes, parallel hydrogenation reactions, and automated analysis. Three of the complexes (5ab, 5ad, and 5dp) and a similar rhodium complex (6ap) were studied by single-crystal X-ray diffraction techniques. This revealed molecular features of 6ap, and presumably the corresponding iridium complex 5ap, that the others do not have. In enantioselective hydrogenations of arylalkenes complex 5ap was the best for many, but not all, substrates. The enantioselectivities and conversions observed were sensitive to minor changes to the catalyst and substrate structure. Ligands with aliphatic N-heterocyclic carbene substituents gave complexes that are inactive, and do not lose the 1,5-cyclooctadiene ligands under the hydrogenation conditions. Experiments to investigate this unexpected observation imply that it is of a steric, rather than an electronic, origin. Temperature and pressure effects on the conversions and enantioselectivities of these reactions had minimal effects for some alkenes, but profound effects for others. In one case, the enantioselectivities obtained at high-pressure/low-temperature conditions were opposite to those obtained under high-temperature/low-pressure conditions (-64% enantiomeric excess versus +89% enantiomeric excess); a transformation from one prevalent mechanism to another is inferred from this. The studies of pressure dependence revealed that many reactions proceeded with high conversions, and optimal enantioselectivities in approximately 2 h when only 1 bar of hydrogen was used. Deuterium-labeling experiments provide evidence for other types of competing mechanisms that lead to D-incorporation at positions that do not correspond to direct addition to the double bond.