Organotin compounds have shown a wide spectrum of biological effects and have been extensively studied as fungicides, bactericides, acaricides and wood preservative. A large number of papers have reported the use of organotin compounds as bacterial growth inhibitors. The biocide activity of tribenzyl- and dibenzyltin compounds has been informed, but the effect that the methoxyl group in the aromatic ring could have on the activity of the compounds has not been reported in previous literature. For that reason, we performed an in vitro qualitative assay, and evaluated the activity of benzyltri-n-butyltin (I) and 3,5-dimethoxybenzyltri-n-butyltin (II) against the growth of two bacterial strains: Staphylococcus aureus (Gram-positive) and Escherichia Coli (Gram-negative), using agar well diffusion method. In all cases Merck Art 5273 broth was employed. THF was used both as the solvent of choice for the organometallic compound (since the organotin compounds are not water soluble) and as a negative control. Different concentrations I and II were prepared and the activity was determined by measuring the diameter of the inhibition zone (in cm). The results proved not only that the Gram-positive strain is more susceptible to the inhibition growth effect of the organotin compounds evaluated, but also that 3,5-dimethoxybenzyltri-n-butyltin has higher antibacterial activity. According to this preliminary results we conclude that the presence of the methoxyl group in the aromatic ring would enhance the antibacterial activity of the organotin compound tested here.

Single-enantiomer drug candidates are important to many pharmaceutical companies, and therefore, new methods for the preparation of enantiopure compounds are critical for the development of next-generation pharmaceutical products. The use of microwave (MW) irradiation in organic synthesis has become a popular technique to develop and optimize the libraries of compounds synthesis in short reaction time compare to those obtained with the classical thermal methods in pharmaceutical and academic production. Numerous studies in the past ten years, demonstrated that microwave enhanced chemical reactions and that they are faster than conventional heating methods. In previuos studies, we reported the stereoselective radical addition of organotin hydrides to unsaturated TADDOL diesters. These reactions occurred with intramolecular cyclization under inert atmosphere, radical initiator, toluene and 75°C with high yields and stereoselectivity depending on the reactivity and steric bulk of the organotin hydride employed. Here, we decided to study a new method for the synthesis of these macrocycles through the radical addition of different triorganotin hydrides, R₃SnH (R= Me, n-Bu, Ph; Neophyl), to the same insaturated TADDOL diesters, in THF as solvent and under MW conditions. We compared these results with the previous reported method. Under MW conditions, reactions were completed in very short reaction time and neither the products of double hydrostannation nor the products of cyclopolymerization were obtained in both cases. Furthermore, we evaluated the stereoselectivity by ¹¹⁹Sn-NMR spectroscopic analysis in both methods.

In this paper we report a simple synthetic route to obtain functionalized allyltin derivatives from 1-ethynylcyclohexene (1), through a "one pot" procedure. Radical addition of trineophyltin hydride to 1 leads quantitatively to (Z,E)-1-(2-trineophylstannylvinyl)-cyclohexene (3), a conjugated dienylstannane that, through a [4+2] cycloaddition reaction (Diels -Alder) with activated dienophiles, allows to obtain substituted bicyclic unsaturated products with specific stereochemistry and a trialkylstannyl group in allylic position.

There is a wide variety of natural and synthetic benzophenones with antibacterial activity. In previous studies,[1] we reported the synthesis of substituted diarylmethanes under Barbier conditions by Stille coupling as precursors of substituted benzophenones. Catalyzed bond formation require hours to days to complete when conventional heating is used, under inert atmosphere. Microwaves have demonstrated that the reaction rate improves significantly and allows use closed vials without inert atmosphere.[2] The Stille coupling was one of the first reactions where the assistance of microwave was applied since some organotin compound have poor reactivity and, consequently, low yield of the desired product. We present here the study of the synthesis of diarylmethanes through Stille reaction under microwave irradiation, comparing the results with and without catalytic conditions and ligands,[3] based on the optimal results applying microwaves without catalyst that have been reported for Suzuki and Sonogashira coupling.[4],[5] In most cases, reactions were completed in short time and no homocoupling product was observed. Although reaction times are slightly higher and the yields were lower than those found in catalyzed condition, the fact that in this case this difficult type of reaction (Csp3-Csp2 coupling) can be performed without catalyst, is very promising and encourages us to continue with future studies in order to find the best conditions. [1] Ocampo, R.A, Koll, L.C, Mandolesi, S.D. Ultrasonics Sonochemistry, Article in press. http://dx.doi.org/10.1016/j.ultsonch.2012.06.014 [2] a) Larhed, M. , Moberg, C., Hallberg, A. Acc. Chem. Res. 2002, 35, 717. b) Olofsson, K., Larhed, M. (Eds.: P. Lidstrum, J.P. Tierney), Blackwell, Oxford, 2004, Chap. 2 [3] a) Larhed, M., Lindeberg, G., Hallberg, A., Tetraheron Lett, 1996, 37, 8219. b) Berthault A., Berteina-Raboin, S., Finaru A., Guillaumet, G., QSAR Comb Sci, 2004, 23, 850 [4] Leadbeater, N.E., Marco, M. J. Org. Chem. 2003, 68, 5660 [5] Leadbeater, N.E., Marco, M., Tominack, B. Org. Lett. 2003, 5, 3919