Patrick T. Campos

Ultrasound promoted the synthesis of N-propargylic β-enaminones.

The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalomethyl[carboxyethyl] ketones [R(3)C(O)CHC(R(1))OMe, where R(3)=CF(3), CCl(3), CO(2)Et and R(1)=Me, Et, Pr, Bu, i-Pent, CH(2)CH(2)CO(2)Me] with propargyl amines [R(2)NHCH(2)CCH, where R(2)=Pr, PhCH(2)] is reported. Yields, solvents and reaction times needed for reaction completion, by microwave irradiation (MW), conventional thermal heating (TH) and under ultrasound irradiation (US) are compared. The best results were obtained under US irradiation in good to excellent yields (70-93%).

Synthesis and Structure of Novel 1-Aryl-4,4,4-trichloro-1,3-butanediones

Abstract Novel 1-aryl-4,4,4-trichloro-1,3-butanediones in good yields (80–97%) were synthesized in one pot through acetal acylation with trichloroacetyl chloride followed by acid hydrolysis. Structures of all compounds were elucidated by elemental analysis, mass spectrometry, and 1H/13C nuclear magnetic resonance (NMR) measurements. The 1H/13C NMR data showed that trichloromethyl-β-diketones 2a–k in solution are predominantly ketoenol. However, the spectroscopic data from 4,4,4-trichloro-2-methyl-1-phenyl-1,3-butabedione (2l) with methyl substituent between carbonyls showed a bias toward the diketo form in solution. X-ray diffraction of monocrystals from 2g and 2i showed that these compounds are cis-ketoenol tautomers. Supplemental materials are available for this article. Go to the publishers online edition of Synthetic Communcations® to view the free supplemental file. GRAPHICAL ABSTRACT

2-Methyl-5-(4-tol-yl)-7-(trifluoro-meth-yl)pyrazolo[1,5-a]pyrimidine.

In the title compound, C15H12F3N3, the pyrazolo[1,5-a]pyrimidine system ring is essentially planar with a maximum deviation from the mean plane of 0.014 (1) Å. The 4-tolyl group makes a dihedral angle of 14.1 (1)° with the pyrazolo[1,5-a]pyrimidine ring system. The crystal packing is stabilized mainly by van der Waals forces.

Regiochemistry of cyclocondensation reactions in the synthesis of polyazaheterocycles

The syntheses of several polyazaheterocycles are demonstrated. The cyclocondensation reactions between β-enaminodiketones [CCl3C(O)C(=CNMe2)C(O)-CO2Et] and aromatic amidines resulted in glyoxalate-substituted pyrido[1,2-a]pyrimidinone, thiazolo[3,2-a]pyrimidinone and pyrimido[1,2-a]benzimidazole. Pyrazinones and quinoxalinones were obtained through the reaction of these glyoxalates with ethylenediamine and 1,2-phenylenediamine derivatives. On the other hand, the reaction of glyoxalates with amidines did not lead to the formation of imidazolones, but rather N-acylated products were obtained. All the products were isolated in good yields. DFT-B3LYP calculations provided HOMO/LUMO coefficients, charge densities, and the stability energies of the intermediates, and from these data it was possible to explain the regiochemistry of the products obtained. Additionally, the data were a useful tool for elucidating the reaction mechanisms.

(S,Z)-3-Phenyl-2-[(1,1,1-tri­chloro-7-meth­oxy-2,7-dioxohept-3-en-4-yl)amino]­propanoic acid monohydrate

In the title compound, C17H18Cl3NO5·H2O, intramolecular N—H⋯O and C—H⋯Cl hydrogen bonds form S(6) and S(5) ring motifs, respectively. The chiral organic molecule is connected to the solvent water molecule by a short O—H⋯O hydrogen bond. In the crystal, a weak C—H⋯Cl interaction connects the organic molecules along [100] while the water molecules act as bridges between the organic molecules in both the [100] and [010] directions, generating layers parallel to the ab plane.