2-Methylbenzothiazole is widely used as the half-product for the thiocyanine dyes photosensitisers synthesis. It usually is synthesized by action of an acetic anhydride in excess on 2-mercaptoaniline. High-temperature reaction of 2-mercaptoaniline derivatives with the organic acids at temperatures above 200oC was extensively studied, but the reaction with acetic acid was not described [1-5]. The method of benzothiazole and its lower 2-alkylsubstituted derivatives synthesis from zinc 2-aminomercaptide and lower aliphatic acids was earlier described, but even in this paper in the examples of 2-methylbenzothiazole synthesis acetic anhydride alone or its mixture with benzene was used [6]. We have elaborated a new efficient method of 2-methylbenzothiazole synthesis from 2-mercaptoaniline and acetic acid shown at the scheme 1

Synthesis of -phenethylamines has been a matter of interest due to their pharmacological properties, and there are several methods to prepare -phenethylamines. Our group has been trying to develop new methods for the hydroamination of styrene, and recently we have communicated our results1. But, when we tried to react lithium anilide(PhNH2/BuLi) with styrene in THF at O C it failed. In a previous work2 there has been reported the hydroamination of styrene with aniline sodium salt by heating for 7 hours at 184 C, and recently, it was reported3 that aniline added to styrene by heating in a sealed tube with Kt-BuO. Now, we attempted to perform the reaction in the absence of solvent and in an open vessel under microwave heating. We used the potassium tert-butoxide as base in a ratio to aniline 1:1, but we have problems with ignition of the reaction mixture. We investigated the influence of several ratios PhNH2/Kt-BuO, founding that a 10% ratio gave the best yield with a 60% of N-phenyl- -phenethylamine, isolated by column chromatography.

Microwave heating has been employed as a frequent resource for improvement of classical reactions, and sometimes it led to discover new reactions. Quinazolines are a kind of compounds well known, whose synthesis has been studied for more than a century. In this paper we describe the use of microwaves to enhance the synthesis of 4-aminoquinazolines. These compounds are of interest due to its pharmacological uses.

Knoevenagel reaction has been object of a complete study1, recently the enhancement of this reaction by microwave heating has been reported by several groups2. We became interested in 3-benzylidene-1,3-dihydroindol-2-ones, as they have been reported as natural products from Isatis indigotica3, although they have been known as pharmacological agents from several years4.

In our group, we have been studying the hydroamination of styrene and its derivatives1. Here, we want to present a preliminary communication about the hydroamination of cinnamyl alcohol. This addition would afford 2-amino-3-phenylpropanols (2), which are of biological interest due to its presence as constituents in the structure of different natural products isolated from many different sources, such as: Allangium lamarckii, Anaphalis subumbellata, Aspergillus flaviceps, A. janus, A. glaucus, Caranthus pusillus, Cystoceria corniculata, Emericellopsis salmosynnemata, Euphorbia fischeriana, Hybanthus enneasperma, Medicago polymorpha, Penicillum canadiense, P.brevicompactum, P. megasporum, Piper aurantiacum and Schismatomma hypothallium.

Pyrrolidines bearing bicyclic skeletons are components of various alkaloids or amino acid derivatives with important physiological activities. The efficient construction of the pyrrolidine ring is important in their synthesis. In the last years, most of the synthetic routes via radical cyclization of heteroatom-containing substrates, are based in generating an alkyl radical by treatment of haloalkanes with a radical initiator such as AIBN. One of the disadvantages of this methodology, which requires working with labile reagents, is the formation of a secondary product arising from the reduction of the halogen atom, on the contrary the copper (I) catalyzed radical atom transfer cyclization lack of this problem. We reported previously the synthesis1 of pyrrolizidines by homolysis of trichloroacetamides in the presence of a catalytic amount of Cu(I). These reactions are usually performed in a sealed tube and heating acetonitrile at temperatures around 150 C2. Although less harsh conditions are needed when TMEDA3and sometimes bipyridine 4 are used.

Introduction of a carbon chain in the -position of amides is a common step to many organic synthesis. Here we describe an improvement in a simple way to achieve 3-chloromethylene-1-methylpyrrolidin-2-one 2, and its reaction with phenyllithium/CuCN to afford 3-arylidene-1-methylpirrolidin-2-one (3), this would represent an approach to a kind of carbon skeleton present in a wide variety of pharmacologically active compounds1. The preparation of 2 was previously reported2 by addition of dichlorocarbene to N-methyl-2-pyrrolidone (1) under phase transfer catalysis (PTC), but the yield reported , using Bu4NCl, was too low (30%) to make it a practical way to achieve 2 in a preparative scale.

Efforts to develop alternatives to blood as an oxygen carrier date back well over half a century with increased efforts in recent years being partly motivated by fears of potential contamination with the viruses responsible for AIDS and hepatitis (1-4). An additional impetus rests in the recognition that wide availability of properly banked blood is absent in many parts of the world. An efficient acellular oxygen carrier could have several distinct advantages over intact red blood cells, including elimination of the need for typing and cross-matching before transfusion and a useful shelf-life greater than the current six weeks or less for packed red blood cells (1). While a number of other alternatives have been explored over the years (1-4), the use of cell-free hemoglobins for an oxygen-carrying resuscitation fluid has excellent prospects since (a) hemoglobin solutions are completely metabolizable and are well tolerated by the body, and (b) hemoglobin is available in virtually unlimited amounts and is relatively inexpensive, (c) hemoglobin is fully saturated with oxygen under ambient conditions, has oncotic activity, and exhibits cooperative oxygen binding behavior. However, there are two major problems associated with using cell-free hemoglobins for transfusions. First, the retention time of cell-free hemoglobins in circulation after infusion is very short (4), and most of the infused hemoglobin is rapidly filtered and eliminated by kidneys in 1-4 hours; second, cell-free hemoglobins have too high oxygen affinity that prevents them from adequately unloading the oxygen acquired from lungs to tissues. Both of these problems have their roots in 2,3-diphosphoglycerate (DPG) and other polyanionic species which are conspicuously absent in cell-free hemoglobins, but are known to be essential co-factors in intact red blood cells. Efforts have since been focused on covalently cross-linking hemoglobin between the two like subunits, e.g., alpha-1 to alpha-2 or beta-1 to beta-2. Such a cross-link is believed to substitute for the native allosteric modifier DPG to lower the oxygen affinity, while at the same time preventing dissociation of the tetramer (1).

ing expanded ("fat") purine nucleosides are of chemical, biochemical, biophysical, and medicinal interest.1-12 The majority of "fat" nucleosides reported from this laboratory in recent yeas were synthesized using the common imidazole precursor, namely 1-benzyl-5-nitro-imidazole- 4-carboxylic acid (I).5-11 However, the synthesis of I suffered from a number of drawbacks, including multi-step procedures, prolonged reaction periods (sometimes days), poor yields, tedious work-ups, and the necessity of separation of regioisomers, all of which contributed to the difficulty in preparing I on a reasonably large scale. We present here an efficient, convenient, and a versatile alternative for I in 5-dichloromethyl-1-p-methoxybenzyl -4-nitroimidazole (II). The latter has a number of novel features which will potentially not only enable the efficient resynthesis of the previously reported "fat" nucleosides from this laboratory, but will also open new ways for the synthesis of a wide variety of novel "fat" nucleosides that would otherwise be difficult to prepare using I. The novel features of II include (a) the presence of a versatile, highly reactive dichloromethyl functional group which can serve as the site of both nucleophilic and electrophilic attacks for further annulation of the appropriate side chain , (b) the potentially facile conversion of the above dichloromethyl group into a wide variety of other reactive functional groups including, but not limited to, a carboxylic acid, a carboxaldehyde, or an iminomethylene functionality, and (c) the attachment of the more conveniently removable p-methoxybenzyl protecting group at the 1-position as compared to the unsubstituted benzyl group of I. In addition, the synthesis of II is brief, convenient, reasonably good-yielding, and can be prepared on a reasonably large scale from readily available and inexpensive starting materials.

Stilbenes are an important class of organic compounds carrying a wide variety of useful applications in organic synthesis. These applications include, but are not limited to, asymmetric dihydroxylation, photocyclization, photodimerization, and synthesis of diphenyl acetylenes, bromohydrins, and benzils. Heterocyclic analogues of stilbenes are of interest not only for exploring these various applications but also for their inherent potential to serve as key precursors to the synthesis of a host of novel as well as known heterocycles containing fused imidazole ring systems. We present here the synthesis and characterization of the title cis- and trans-1,2-bis(4-nitro-1-p-methoxybenzylimidazol-5-yl)ethene, I and II.