7722-64-7

The invention relates to a process for preparing a compound of the formula (I) in which R is methyl or carboxyl, which comprises coupling an ortho-tolylmetallate of the formula (II) with a compound of the formula (III) in which M is —MgF, —MgCl, —MgBr, —Mgl, —Li, —ZnF, —ZnCl, —ZnBr or —Znl and X is F, Cl, Br, I, N2+, straight-chain or branched (C1-C20)-alkoxy, arylsulfonate or alkylsulfonate in the presence of an Ni, Pd or platinum metal catalyst to give a compound of the formula (I) where R is CH3 and, if appropriate, oxidizing the compound of the formula (I) where R is CH3 to give the compound of the formula (I) where R is carboxyl.

The invention relates to a process for the preparation of optically active ortho-substituted 4-aryl- or heteroaryl-1,4-dihydropyridines by oxidation and subsequent reduction from their opposite enantiomers.

The rate of outer-sphere electron transfer between MnO4- and MnO42- in aqueous MOH at constant ionic strength (1.1 mol L-1) is given by (k0 + kM[M+])[MnO4-][MnO4 2-], where k0 is defined by the activation parameters ΔH0* = 46 kJ mol-1, ΔS0* = -35 J K-1 mol-1, ΔV0°*(0.1 MPa, 318 K) = -23 cm3 mol-1, and Δβ0* ? -0.06 cm3 mol-1 MPa-1. For M = Li, Na, K, and Rb, respectively, kM is given by ΔHM* = 33.1, 32.2, 32.9, and 32.9 kJ mol-1 and ΔSM* = -67.8, -68.4, -62.9, and -59.0 J K-1 mol-1, while, for M = Na and K, ΔVM* = +3 and -1 cm3 mol-1. The activation parameters for the cation-independent reaction pathway can be accounted for by a modified semiclassical Marcus-Hush theory if, in the transition state for adiabatic or nearly adiabatic electron transfer, the reacting ions are taken to be enclosed within a common cavity in the solvent and the Mn-Mn distance compresses as does the cavity, which is assumed to have the same compressibility as the solvent itself. The lower enthalpies, and markedly more positive volumes, of activation for the M+-catalyzed pathway appear to arise at least in part from an easing of these solvational constraints.

Dichloropinacolone is produced by introducing into pinacolone twice the molar amount of chlorine, the exothermic reaction mass being cooled initially to maintain the temperature below about 50° C until about 60 to 80% of the chlorine has been introduced, and then heating the reaction mass to a temperature above 50° C during introducing of the remainder of the chlorine, thereby to produce dichloropinacolone, and terminating chlorine introduction when the dichloropinacolone content of the reaction mass is at least about 97%. The molten product is added to an aqueous solution of an alkali maintained at a temperature of at least about 50° C, the alkali being present in more than three times the molar amount of the dichloropinacolone. To the resulting solution of a salt of 3,3-dimethyl-2-hydroxy-butyric acid, brought to a pH of about 9 to 12, there is added approximately the stoichiometric amount of potassium permanganate. Solid MnO2 precipitates out and is separated from the substantially pure dissolved salt of 3,3-dimethyl-2-oxo-butyric acid. The product is a known compound suited for further syntheses.

The assymetric stretching frequencies of barium manganates (V) (VI) and (VII), chromate (V) and orthovanadate and other Td-transition barium oxometalates are correlated with the electronic structure of the complex anions. Influence of nuclear charge and number of π antibonding electrons upon ν3 is thereby shown.