Alice Dias

Synthesis of 9-hydroxyalkyl-substituted purines from the corresponding 4-(C-cyanoformimidoyl)imidazole-5-amines

The amino alcohols HO(CH2)n NH2(n= 2, 3 and 5) react readily with ethyl (Z)-N-(2-amino-1,2-dicyanovinyl)formimidate 5 to give the amidines 6a-c, which cyclize in the presence of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) to give the corresponding 4-(cyanoformimidoyl)imidazole-5-amines 7a-c, which can be isolated in the cases where n= 2 or 3.In the presence of aldehydes and ketones, the imidazoles 7a-d lead to the 6-carbamoyl-1,2-di-hydropurines 9a-f which, in some cases, are oxidised to the corresponding 6-carbamoylpurines.The reaction of the imidate 5 with 2-methoxyethylamine leads to the amidine 6d and, on treatment with DBU, the reactive imidazole 7d which can be used directly for further reaction.

Synthesis and antimicrobial activity of novel 5-aminoimidazole-4-carboxamidrazones.

A mild and simple method was developed to prepare a series of fifteen 5-aminoimidazole 4-carboxamidrazones, starting from the easily accessible 5-amino-4-cyanoformimidoyl imidazoles. The antimicrobial activity of these novel amidrazones was screened against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli, Pseudomonas aeruginosa) bacteria and Candida sp. (Candida albicans, Candida krusei, Candida parapsilosis). Only a subset of compounds displayed fair-moderate activity against S. aureus and E. coli but all exhibited activity against Candida sp. The three most potent antifungal compounds were further tested against Cryptococcus neoformans, Aspergillus fumigatus and three dermatophytes (Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum gypseum). These three hit compounds strongly inhibited C. krusei and C. neoformans growth, although their activity on filamentous fungi was very weak when compared to the activity on yeasts.

A new and efficient approach to the synthesis of 6-amidino-2-oxopurines

The reaction of 5-amino-4-cyanoformimidoylimidazoles 1a and 1b with tosyl isocyanate proved to be a mild and efficient method for the synthesis of the corresponding 6-amidino-2-oxopurines 5. These compounds, which were isolated in almost quantitative yield, rearrange in the presence of acetic acid–DMF to give a pyrimido[5,4-d]pyrimidin-2-one 6. The structure of compound 6 was confirmed by X-ray crystallography. The pathway for both reactions is discussed. Studies on the reactivity of tosyl isocyanate with imidazoles 2, 7, 8 and 16, obtained from 1 by selective acylation of the amino or imino nitrogen atoms, enabled clarification of the mechanism for purine formation.

Numerical Analyses of Timber Columns Reinforced by Particulate Composite Material

Beams are structural elements commonly used in structure for construction designs. Usually wood is applied as structural elements and its use is very important because it is a material of renewable source, low density and satisfactory mechanical performance. When the wood surface is not properly treated, the structure can be destroyed not only by environmental conditions but also the attack of insects, compromising the structural design. This research presents the use of a particulate composite material of epoxy resin reinforced with white Portland cement in order to be applied as repair in timber columns. The mechanical performance of this material is essentially numerical, based on the Finite Element Method. The wood used in the simulation was the Eucalyptus grandis. The elastic properties were obtained from the specialist literature in the field of timber structures. The results of numerical simulations in terms of tension and buckling loads, the inclusion of the composite in the damaged regions (for all dimensions of the defects studied) provided buckling load results significantly higher than the buckling load values for the conditions without composite, and near to the values of the buckling loads without defect, highlighting the good performance of the particulate composite material in the repair of timber columns. INTRODUCTION Columns and beams are fundamental elements in the majority of structures. In a building, we highlight the use of wood for being a renewable source material, presenting excellent relationship between strength and density, according to [1] this gets to be four times higher when compared to steel. The wood, which until the early twentieth century represented one of the main structural materials in construction [2]. The buildings constructed with wood require appropriate maintenance and use. According to [3], structural elements of wood are susceptible to variations in their mechanical properties due to natural factors, such as growing conditions Accepted: November 5, 2015 * Address correspondence to this author at the Centre for Innovation and Technology in Composites (CITeC), Department of Civil Engineering (DECiv), Federal University of São Carlos (UFSCar), São Carlos, 13565-905, Brazil; Tel: (+55) 16 33066828; E-mail: christoforoal@yahoo.com.br