Thomas J. Kress

Synthesis and proton NMR spectra of the monomethyl- and dimethylpyrimidine-5-carboxylic acids. Regioselective covalent hydration at the 2- and 4-ring positions

Pyrimidine-5-carboxylic acid, its 2-methyl-, 4-methyl, 2,4-dimethyl- and 4,6-dimethyl derivatives have been synthesized and their proton nmr spectra measured in dilute aqueous acid. Pyrimidine-5-carboxylic acid (1a, R 2,4,6 = H) was found to afford an equilibrium mixture of covalent hydrates at both the 2- and 4-ring positions (2a and 3a). The 2-methyl derivative (1b, R 2 = Me, R 4,6 = H) undergoes hydration exclusively at the 4-position (2b) while the 4-methyl derivative (1c, R 2,6 = H, R 4 = Me) hydrates selectively at only the 2-position (3c). Covalent hydration was not observable for either the 2,4-dimethyl- (1d, R 2,4 = Me, R 6 = H). or 4,6-dimethyl- (1e, R 2 = H, R 4,6 = Me) pyrimidinecarboxylic acids. The synthetic routes to these substances are described and the degree of hydration for each compound was measured

Diastereoselectivity in ergoline synthesis: a face selective epoxidation

Abstract Epoxidation of 1-Benzoyl-1,2,2a,3-tetrahydrobenz[ cd ]indole ( 4a ) proceeded smoothly with metachloroperbenzoic acid with high exo diastereoselectivity (de = 96%) and chemical yield (97%). The basis for this selectivity was probed with substituent effects, and was extended to other oxidation media.