Letters in Organic Chemistry - Volume 10, Issue 6, 2013

An effective procedure for the synthesis of long-chain alkyl esters of aminoacids is described. The procedure was studied for the practical synthesis of methionine nonylate, using tosyl chloride to generate in situ intermediate tosylates of aminoacids.

Free base porphyrin-cored arylether dendrimers 2a∼2c with terminal hydroxy groups in the periphery have been successfully prepared by hydroboration-oxidation reaction of corresponding 1a∼1c with terminal vinyl groups in the periphery. Their zinc derivatives Zn-2a∼Zn-2c have also been prepared. Absorption and fluorescence properties of 2a∼2c and Zn-2a∼Zn-2c with peripheral hydroxy groups were affected more by dendritic environments than 1a∼1c and Zn- 1a∼Zn-1c with peripheral vinyl groups.

The syntheses, antioxidant activities, acidity properties, experimental and theoretical investigations of vibrational spectra (FT–IR and micro–Raman), 13C and 1H NMR chemical shifts and electronic properties of 3–alkyl–4–[3– methoxy–4–(4–methylbenzoxy)benzylidenamino]–4,5–dihydro–1H–1,2,4–triazol–5–one (Me, Et and n–Pr) molecules have been presented for the first time. The new compounds were analyzed for their potential antioxidant activities in three different methods.The calculations of molecular structures, vibrational frequencies, 13C and 1H NMR chemical shifts and electronic absorption wavelengths of the title molecules were computed by using the DFT/B3LYP method with 6– 31G(d) basis set which was used to have the structural and spectroscopic data about the mentioned molecules in the ground state and the results calculated were compared with experimental values. Furthermore, gauge invariant atomic orbital (GIAO) 1H and 13C NMR chemical shifts in different solvents (gas phase, DMSO and cholorofom), UV–vis. TD– DFT calculations in ethanol solvent, the highest occupied molecular orbital (HOMO–1, HOMO), lowest unoccupied molecular orbital (LUMO, LUMO+1), molecular electrostatic potential map (MEP), atomic charges and thermodynamic properties of the title compounds have theoretically verified and simulated at the mentioned level. In addition, the calculated infrared intensities and Raman activities of the compounds under study have also been reported.

An ionic supported triphenylphosphine and carbon tetrabromide system has been applied to the clean and efficient conversion of various aromatic and aliphatic aldehydes to the corresponding nitriles.

A new and facile one-pot synthesis of the biologically important spiro[quinazoline/pyrimidine]ones scaffold was synthesized simply by the reaction of isatin, 1,3-dione and urea or thiourea. The scope of the reaction was successfully extended by employing two other reactive ketones (acenaphthylene-1,2-dione and ninhydrin) instead of isatin. A series of new spiro cyclic derivatives via multi-component reaction was obtained by using guanidine and employing different 1,3 - dicarbonyl compounds.

A simple and efficient synthesis of pyran annulated heterocyclic compounds has been developed by reaction of aryl aldehydes, malanonitrile and cyclic-1,3-diketones using tetra butyl ammonium acetate (TBAA) melt as cost-effective and recyclable ionic liquid under solvent-free i.e green conditions at 100 °C for 10 minutes without additional use of catalyst.

The synthesis of some novel (spirocycloalkenyl)trimethylsilylacetylenes employing the Sonogashira coupling reaction of the corresponding novel spirocycloalkenyliodides with trimethylsilylacetylene and Pd(PPh3)2Cl2/CuI catalyst in yields ranging 79-84% is reported. The compounds would serve as novel (spirocycloalkenyl)acetylenic anionic synthons.