The reaction of 1-(methylthio)acetone with different nitriles in the presence of triflic anhydride led to the one-pot formation of 2-substituted 5-methyl-4-methylthio-1,3-oxazoles in good yield. 1,2- and 1,4-Bisozaxolyl-substituted benzenes were obtained when the reaction was carried out using aromatic dinitriles. The methylthio group at the C4 position of the oxazole ring was easily removed with Raney nickel to form 2-substituted 5-methyl-1,3-oxazoles in good yields. 4-Methylsulfonyl derivatives were prepared by the oxidation of the MeS group with m-CPBA. The proposed mechanism for the formation of oxazoles involves an unstable 1-(methylthio)-2-oxopropyl triflate, which was detected from the low-temperature NMR spectra.

A part of the "bouquet of wines" can be caused by the presence of odorous heterocycles produced by chemical reactions between S-amino acids and α-dicarbonyl compounds. Under wine ageing physic-chemical conditions (20 ± 2 °C, ethanol/water 12% v/v, pH 3.5), products of the diacetyl (DI) reaction with cysteine include a number of 1,3-N,S and 1-3-N,O 5 member heterocycles having methyl groups attached at C(2). The origin of this methyl-C(2) fragment was not clear; it could be supplied from DI or from cysteine. To explore this question, a parallel reaction was run in which DI was replaced by 3,4-hexanedione. With the C(1) and C(4) carbons of DI thus marked with methyl groups, the product distribution demonstrated that in the DI and cysteine reaction, both DI and cysteine provided the methyl-C(2) to varying degrees in the formation of 2-methylthiazole, 2-methyl-3-thiazoline and 2,4,5-trimethyloxazole but only cysteine supplied this fragment for 2-methylthiazolidine. The results are interpreted in terms of reaction paths appropriate for the mild conditions. These pathways shed light on the mechanisms leading from dicarbonyls to heterocyclic compounds. Like all the chemical pathways, they anticipate the impact of other compounds and physicochemical parameters on heterocyclic generations the generation of heterocyclics. They also suggest the presence of unexplored odorous compounds.

For study of base-catalyzed proton transfer, (-)-3-/-butyl-l-methylindene-l-/z ((-)-I-h), (-)-3-?-butyl-1 -methylindene-1 -d ((-and (+)-l-f-butyl-3-methylindene-1 -h ((-f-)-II-A) of maximum rotations were prepared. Comparisons of their optical rotatory dispersion curves and those of their ketonic precursors, (-)-(Z?)-3methyl-1-indanone ((-)-(/?)-IV) and (-)-3-/-butyI-l-indanone ((-)-(S)-VI), established that (-)-l-h and (+)-ll-h possess opposite configurations. Optically pure ketones (-)-VI undeuterated at the chiral center, deuterated at the chiral center, and dideuterated at the position a to the ketonic group differ in rotations by unusually large amounts up to 300% at 390 µ. This effect is attributed mainly to the difference in steric requirements of H and D, and the consequent change in dihedral angle about the C2-C3 bond of the deuterated and nondeuterated indanones. Equilibrium constants for I <=± II were found to be 5.99-6.04 at 102°( r-butyl alcohol-triethylenediamine), 6.64-6.69 at 48°( 10 mol % methanol-90 mol % dimethyl sulfoxide-triethylenediamine), and 7.50-7.60 at 25 °(tetrahydrofuran, 2.0 M in «-propylamine). Under conditions that II was stable to exchange, racemization, or isomerization, I was isomerized to II; the two isomers were separated and analyzed for isotopic exchange and racemization. In all runs with amine catalysts and with transfer of either hydrogen or deuterium with solvents ranging from dimethyl sulfoxide-r-butyl alcohol to benzene (-)-I gave (+)-II of 97-100% optical purity, and recovered (-)-I was 98-100% optically pure. Proton transfer involved almost exclusively only one face of the allylic anion. With I-h in r-butyl alcohol-O-rf with triethylenediamine as base and in the presence of deuterated amine salt as a primary isotope pool, the (-f-)-II produced had undergone only 0.35% isotopic exchange. In dimethyl sulfoxide, 1.0 M in tbutyl aicohol-O-d with the same base and salt, the (+)-II had undergone 1.2% isotopic exchange. In tetrahydrofuran, 0.61 M in «-propylamine, l-d gave II that was 95% exchanged, whereas with I-H and deuterated amine in the same solvent the II produced was 36% exchanged. Recovered I from these experiments gave ke!ka (rate constant for isotopic exchange over that for racemization) values >7.5. These experiments demonstrate that in the alkylammonium carbanide ion pair, alkylammonium ions reorganize enough to provide for extensive isotopic exchange, and that protium is captured by the anion more efficiently than deuterium. In benzene, 0.10 M in piperidine, l-d gave II with 27% isotopic exchange, whereas in benzene, 0.10 M in deuterated piperidine, l-h gave II with only 13% isotopic exchange. In this ion-pair intermediate, the dialkylammonium ion moved across the t cloud of the allylic anion and donated a proton or deuteron to the new site faster than the ammonium ion rotated. The anion of these contact ion-pair intermediates appears mainly to hydrogen bond no more than one hydrogen at a time.the first elegant kinetic results of Bergson, et al.f ap-(1) This r...

An analysis for urea in wine was developed in which urea is isolated by ion exchange and then derivatized with 1-phenyl-1,2-propanedione 2-oxime. Measurements of the derivative are made by colorimetry. The analysis gave good linear response to additions of 0-50 mg/L of urea to either red or white wine. Blank experiments in which either urea or l-phenyl-l,2-propanedione 2-oxime was withheld with either red or white wine samples or model solutions gave less than 1.0 mg/L of urea in all cases. Good agreement was obtained for wine samples that were submitted to the present method and one to HPLC.

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