Publications > Cañeque et al

Eur. J. Org. Chem. 2010, 6323

Heteroaromatic Cation-Based Chromophores: Synthesis and Nonlinear Optical Properties of Alkynylazinium Salts

Tatiana Cañeque, Ana M. Cuadro, Julio Alvarez-Builla, Javier Pérez-Moreno, Koen Clays, Gema Marcelo, Francisco Mendicuti, Obis Castaño, José L. Andrés, Juan J. Vaquero

Palabras clave: Heterocycles; Cations; Chromo­phores; Synthesis; Nonlinear ­optics

Resumen

Abstract A variety of alkynylazinium cationic (D-π-A%@2B) chromophores were prepared in good yields by the reaction of bromoazinium (pyridinium, quinolinium, and isoquinolinium iodides) with alkynes under Sonogashira conditions. The analysis of the experimentally recorded spectra is supported by quantum chemical calculations using restricted configuration interaction and density functional methods. First-order hyperpolarizabilities of (D-π-A%@2B) azinium-based cations as a new class of second-order nonlinear optical (NLO) chromophores were also studied by hyper-Rayleigh scattering experiments and computational procedures.

Publications > Baeza et al

Eur. J. Org. Chem. 2010, 5607

Application of Selective Palladium-Mediated Functionalization of the Pyrido%@5B3′,2′:4,5%@5Dpyrrolo%@5B1,2-c%@5Dpyrimidine Heterocyclic System for the Total Synthesis of Variolin B and Deoxyvariolin B

Alejandro Baeza, Javier Mendiola, Carolina Burgos, Julio Alvarez-Builla, Juan J. Vaquero

Palabras clave: Cross-coupling; Total synthesis; Natural products; Heterocycles

Resumen

Abstract The reaction of protected 3-bromo-2-(bromomethyl)-4-methoxypyrrolo%@5B2,3-b%@5Dpyridine and tosylmethyl isocyanide (TosMIC) afforded a pyrido%@5B3?,2?:4,5%@5Dpyrrolo%@5B1,2-c%@5Dpyrimidine derivative in good yield. This compound was transformed through installation of the pyrimidine moiety in the C5 position, hydrolysis, and decarboxylation in an advanced intermediate for the total or formal synthesis of the naturalalkaloid variolin B. Reaction of 3-bromo-2-(bromomethyl)-4-chloropyrrolo%@5B2,3-b%@5Dpyridine with N-tosylmethyl dichloroformimide as a synthetic TosMIC equivalent afforded trihalo-substituted pyrido%@5B3?,2?:4,5%@5Dpyrrolo%@5B1,2-c%@5Dpyrimidine. This compound was used in a new total synthesis of the alkaloid variolin B by selective and sequential C?N, C?C, and C?O palladium-mediated functionalization at the C9, C5, and C4 positions of the pyrido%@5B3?,2?:4,5%@5Dpyrrolo%@5B1,2-c%@5Dpyrimidine system. A formal synthesis of deoxyvariolin B is also described by using the same synthetic strategy.

Publications > Deligeorgiev et al

Phosphorus, Sulfur, and Silicon and the Related Elements 2010, 185, 2292

Novel Green Procedure for the Synthesis of 2-Arylbenzothiazoles Under Microwave Irradiation in Peg 200 Or Peg 400

Todor G. Deligeorgiev, Stefka Kaloyanova, Aleksey Vasilev, Juan J. Vaquero

Resumen

An improved green procedure for the synthesis of 2-aryl- and 2-hetarylbenzothiazoles by condensation of equivalent amounts of 2,2?-diaminodiphenyldisulfides or 2-aminothiophenols and various aromatic aldehydes in PEG 200/400 under microwave irradiation has been developed. This method allows the synthesis of 2-arylbenzothiazoles in high yields and with high purity regardless of the state of the starting compounds (liquid or solid) or the nature of the substituents in the aromatic ring.

Publications > Deligeorgiev et al

Coloration Technology. 2010, 126, 55

Styryl dyes – synthesis and applications during the last 15 years

Todor Deligeorgiev, Aleksey Vasilev, Stefka Kaloyanova, Juan J Vaquero

Resumen

One of the most widely used and important groups of functional dyes are the styryl dyes and a review of this functional dye class has not been published for more than 15?years. In this review article, we describe the new trends in the synthesis of a range of novel intermediates and styryl dyes and include the most interesting examples of their high-tech applications. However, this review is not intended to be comprehensive because of the large number of styryl dye studies that have been carried out in this time. Styryl cyanine dyes are widely used in optical recording media in laser discs, as flexible dyes, laser dyes, as optical sensitisers and in various other fields, for example dye-sensitised solar cells and dyes with non-linear optical properties. Additionally, the most important applications for these dyes are in bio-labelling and in medicinal analysis.

Publications > Deligeorgiev et al

Mini-Reviews in Organic Chemistry. 2010, 7, 44

Green chemistry in organic synthesis.

T. Deligeorgiev^1, 2, N. Gadjev, A. Vasilev, S. Kaloyanova, J.J. Vaquero, J. Alvarez-Builla

1. University of Sofia, Faculty of Chemistry, 1164 Sofia, Bulgaria.  2. University of Alcalá, Faculty of Pharmacy, 28871 Alcalá de Henares, Madrid, Spain.

Resumen

The development of the concepts for "Green Chemistry" and the main principles of this field are reviewed. Examples of the application of these principles in different areas of chemistry are included. The frequently used alternative solvents (green solvents - water, PEG, perfluorinated solvents, supercritical liquids) in preparative organic chemistry are described. The present and the future developments of green chemistry in education and organic chemical technology are considered. © 2010 Bentham Science Publishers Ltd.

Publications > Deligeorgiev et al

Coloration Technology 2010, 126, 24

Novel environmentally benign procedure for the synthesis of 2-aryl- and 2-hetaryl-4(3H)-quinazolinones

T G Deligeorgiev, St Kaloyanova, A Vasilev, J-J Vaquero, J Alvarez-Builla, Ana M Cuadro

Resumen

A novel environmentally benign procedure for the synthesis of 2-aryl- or 2-hetaryl-4(3H)-quinazolinones by condensation of anthranilamide with various aromatic aldehydes in polyethylene glycol under microwave irradiation has been developed. In contrast with other reported methods, this procedure provides the corresponding quinazolinones with good to high yields and purity, in very short reaction times and without the use of an oxidant.

Publications > Deligeorgiev et al

Ultrasonics Sonochemistry 2010, 17, 783

An easy and fast ultrasonic selective S-alkylation of hetaryl thiols at room temperature

Todor Deligeorgiev, Stefka Kaloyanova, Nedyalko Lesev, Juan J. Vaquero

Palabras clave: Selective S-alkylation; Mercaptoazoles; Ultrasound irradiation

Resumen

A series of 2-alkylthio derivatives of hetaryl thiols were synthesized by selective S-alkylation with alkyl halides (bromides and iodides) with ultrasonic irradiation at room temperature. The reaction was found to be generally applicable to hetaryl thiol derivatives with different substituents in the aromatic nucleus and various alkyl halides. The reaction gives high to excellent yields of products with high purity.