Mycotoxins are toxic secondary metabolites produced by filamentous fungi that occur naturally in agricultural commodities worldwide. Aflatoxins, ochratoxin A, patulin, fumonisins, zearalenone, trichothecenes, and ergot alkaloids are presently the most important for food and feed safety. These compounds are produced by several species that belong to the Aspergillus, Penicillium, Fusarium, and Claviceps genera and can be carcinogenic, mutagenic, teratogenic, cytotoxic, neurotoxic, nephrotoxic, estrogenic, and immunosuppressant. Human and animal exposure to mycotoxins is generally assessed by taking into account data on the occurrence of mycotoxins in food and feed as well as data on the consumption patterns of the concerned population. This evaluation is crucial to support measures to reduce consumer exposure to mycotoxins. This work reviews the occurrence and levels of mycotoxins in Portuguese food and feed to provide a global overview of this issue in Portugal. With the information collected, the exposure of the Portuguese population to those mycotoxins is assessed, and the estimated dietary intakes are presented.

5-Amino imidazole 4-substituted carboxamidines and 4-substituted imidoyl cyanides were selectively obtained under mild experimental conditions from reaction of the easily accessible 5-amino-4-cyanoformimidoyl imidazoles with primary aliphatic and aromatic amines, ammonia, and amino acids in a one-pot reaction. When alcohols were used, the corresponding 5-aminoimidazole 4-carboximidates were isolated. An equally simple reaction occurred when the starting imidazoles were combined with water to give 5-aminoimidazole 4-acyl cyanides.Imidazoles are key components in a large number of biomolecules and pharmacologically active compounds. They can be considered important scaffolds in heterocyclic synthesis and drug discovery. 1,2 Examples include the essential amino acid histidine and related compounds, biotin, imidazole alkaloids, antifungal ketoconazole, antiulcerative agent cimetidine, and the proton-pump inhibitor omeprazole. 1,2dThe a-iminonitriles (also referred to as imidoyl cyanides) are an important class of functionalized compounds used as precursors for a-keto acids, amides, N-alkylketene imines, cyanoenamides, amidines, etc. 3 These compounds are usually obtained through multistep processes, with limited application scope.Amidines, important synthons in heterocyclic chemistry, are mostly prepared from nitriles (Pinner synthesis) via imidates and usually require activated nitriles or forcing conditions. 4 The synthesis of a series of triazolo-3-(Nsubstituted) carboxamidines incorporating different alkyl amines and amino acids has been reported and involves a carboximidate as a key intermediate, prepared from the corresponding carbonitrile. 5The chemistry of 5-aminoimidazoles has not received much attention and this has been attributed to their lower stability, as compared to other classes of aminoazoles. 2e,6,7 Nevertheless, the synthesis of 5-aminoimidazole 4-carboxamidine from a carbonitrile via a carboximidate has been reported. 8 Herein we describe a new, more facile, and versatile synthesis of 5-aminoimidazole 4-carboxamidines from 5-amino-4-cyanoformimidoyl imidazoles 1.Imidazoles 1 are easily prepared following a previously developed method. 9 These imidazoles react with secondary amines at the imine carbon atom of the cyanoformimidoyl substituent with subsequent elimination of HCN. 9d We now report the incorporation of primary amines, amino acids, ammonia, alcohols, and water into the substituent in the 4-position of the imidazole ring using trifluoroacetate and hydrochloride salts of imidazoles 1 as key intermediates.During studies on the reaction of imidazoles 1 with anhydrides, 9c,10b,c we realized that imidazolium trifluoroacetate 1a·TFA was generated in 95% yield from trifluoroacetic anhydride (TFAA) and not the desired imidazole 2a ( Table 1). The reaction of 1a with trifluoroacetic acid (TFA) led to the same salt in 88% yield. From preliminary studies on the reactivity of 1a·TFA, two important results emerged. In the presence of methanol the carboximidate 3a·TFA was isolated in 76% yield after...

S y n t h e s i s o f 3 -I m i d a z o l y l 1 , 2 , 4 -T r i a z o l e s a n d 1 , 2 , 4 -O x a d i a z o l o n e s

5-Amino-4-(N-ethoxycarbonyl)formamidino imidazoles were prepared from 5-amino-4-(N-ethoxycarbonyl)cyanoformimidoyl imidazoles and primary alkyl amines, under mild experimental conditions. The product imidazoles were selectively cyclized to N 6 -substituted isoguanines by reflux in acetonitrile with one equivalent of sulfuric acid, followed by neutralization. The same imidazoles led to N 1 -alkylisoguanines as the major product upon reflux in ethanol.

Treatment of N‐aryl‐ or N‐alkyl‐5‐amino‐4‐(cyanoformimidoyl)‐1H‐imidazoles 1 with benzoyl or ethoxycarbonyl isocyanates resulted in the formation of 5‐amino‐4‐[N‐benzoyl‐ or N‐(ethoxycarbonyl)carbamoylcyanoformimidoyl]‐1H‐imidazoles 2. In the presence of catalytic amounts of DBU (1,8‐diazabicyclo[5.4.0]undec‐7‐ene), these compounds cyclized to give the 5′‐amino‐5‐imino‐4,4′‐bi‐1H‐imidazol‐2(5H)‐ones 3. Compounds 3 efficiently rearrange to yield 6‐amidino‐2‐oxopurines 5 in ethanol or DMF solution. The formation of purines 5 both from imidazoles 2 and from bi‐imidazoles 3 was followed by 1H NMR, allowing a deeper understanding of the reaction mechanism. The rearrangements are acid‐catalysed (trifluoroacetic acid), but the use of one equivalent of acid produced different products, identified as the bi‐imidazoles 8.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)