Diastereo-selectivity in diels–alder cycloadditions of erythrose benzylidene-acetal 1,3-Butadienes with maleimides

Maleimides were combined with D-erythrose benzylidene-acetal 1,3-butadienes 1 and 2 to study the facial selectivity of the Diels-Alder cycloadditions. The selectivity was found to be from moderate to good. The reaction diastereotopicity can be reversed with the temperature. Simultaneous coordination of diene 1, having a free hydroxyl group, and maleimide 3 to a chiral bimetallic Lewis acid catalyst (LACASA-DA reaction) occurs with complete diastereo-control to give a single adduct, using an extra chiral inductor either R- or S-BINOL.Thanks are due to FCT for project funding PTDC/QUI/67407/2006 and FCT and FEDER for funding the NMR spectrometer Bruker Avance III 400 as part of the National NMR Network. V. C. M. D. also thanks for PhD grant (SFRH/BD/61290/2009)

ADENOPATIA CERVICAL COMO MANIFESTAÇÃO DE CANCRO DO CÓLON

Introduction: Colorectal cancer is one of the most frequent cancers worldwide, being the third most common cancer diagnosed and corresponding to the second cause of death by cancer. Approximately 25% of patients have already disseminated disease at the time of diagnosis. Case Report: We present the case of a 68-year-old female patient presented with complaints of cervical mass. She was then submitted to a biopsy of the cervical adenopathy that revealed metastatic adenocarcinoma tissue with probable gastrointestinal origin. A work-up was performed and revealed a sigmoid colon adenocarcinoma. Due to associated morbidities she was submitted to supportive treatment. Discussion: This case demonstrates the singularity of metastatic pattern in colon carcinoma. The mechanism of distant lymph node metastases in colorectal cancer still remains uncertain, nevertheless this represents an advanced stage of the disease that bears a poor prognosis. Conclusion: Few reports in the literature showed a good outcome with primary tumor excision and adjuvant chemotherapy but this decision should be discussed in a multidisciplinary team in order to decide the best treatment option for each patient.Introdução: O cancro colorectal é um dos cancros mais frequentes a nível mundial, sendo o terceiro cancro mais frequentemente diagnosticado e corresponde à segunda causa de morte por cancro. Cerca de 25% dos doentes apresentam doença disseminada à data de diagnóstico. Caso Clínico: Os autores apresentam o caso de uma doente de 68 anos, do sexo feminino, que se apresentou com queixas de uma tumefacção cervical. Foi posteriormente submetida a biópsia excisional que revelou a presença de metástase de adenocarcinoma provavelmente intestinal. Foi realizado o estudo complementar com identificação de um adenocarcinoma do cólon sigmoide. Devido às morbilidades associadas foi oferecido tratamento de suporte. Discussão: Este caso representa a singularidade do padrão de metastização do cancro do cólon. O mecanismo de metastização ganglionar à distância não se encontra totalmente esclarecido, no entanto, representa um estadio de doença avançado com um mau prognóstico associado. Conclusão: Alguns casos na literatura demonstraram bons resultados com a excisão do tumor primário seguida de quimioterapia adjuvante, esta decisão deve ser realizada por uma equipa multidisciplinar de forma a avaliar a melhor opção terapêutica para cada doente

The synthesis of an homochiral aziridine as a useful synton to iminosugars and amino acid compounds

Fundação para a Ciência e a Tecnologia (FCT) - PTDC/QUI/67407/200

Diastereoselective synthesis of analogues of neuraminic acid

Siliac acids frequently terminate oligosaccharide side chains in glycoproteins and glycolipids. In this position they have been found to mask recognition by proteases or glycosidases, extending glycoproteins and glycolipids lifetime and function.1 The interest in the sialic acids chemistry in which neuraminic acid is included has rapidly increased in last years, especially since their involvement in the regulation of a great variety of biological phenomena was recognised.2 In our previous work, we found that combination of D-erythrose 1,3-butadiene with t-butyl 2H-azirine 3-carboxylate through Diels-Alder cycloaddition gave as major product the (R)-configured cycloadduct 1, in 58% yield.3 Analogues of neuraminic acid can be achieved from this adduct in a few steps, following different methods of oxidation of the double bound (Scheme 1). Osmilation of the cycloadduct was found to be totally stereo-selective, the addition occurring by the si face. After benzylidene acetal cleavage under acid hydrolysis was obtained product 2. On the other hand, epoxidation of the cycloadduct followed by nucleophilicic ring-opening will give access to the configuration described in compounds 3, and by aziridination of the epoxide is achieved the L-gluco neuraminic acid configuration.We thank FCT for project funding PTDC/QEQ-MED/1671/2012; the NMR Portuguese network (PTNMR, Bruker Avance III 400-Univ. Minho), and FCT and FEDER (European Fund for Regional Development)-COMPETE-QREN-EU for financial support to CQ/UM.info:eu-repo/semantics/publishedVersio

Advances in the synthesis of Homochiral (-)-1-azafagomine and (+)-5-epi-1-azafagomine. 1-N-phenyl carboxamide derivatives of both enantiomers of 1-azafagomine: leads for the synthesis of active α-Glycosidase inhibitors

- A new expeditious preparation of homochiral (-)-1-azafagomine, and (+)-5-epi-1-azafagomine has been devised. Stoodley´s diastereoselective cycloaddition of dienes bearing a 2,3,4,6-tetraacetyl glucosyl chiral auxiliary to 4-phenyl-1,2,4-triazole-3,5-dione, was merged with Bols protocol for functionalizing alkenes into molecules bearing a glucosyl framework. Homochiral (+)-5-epi-1-azafagomine was synthetized for the first time. Partial reductive cleavage of the phenyltriazolidinone moiety afforded new homochiral 1-N-phenyl carboxamide derivatives of 1-azafagomine. Both enantiomers of these derivatives were synthetized and tested, displaying a very good enzymatic inhibition towards baker´s yeast α-glucosidase. The molecular recognition mechanism of the 1-N-phenyl carboxamide derivative of 1-azafagomine by α-glucosidase from baker´s yeast was studied by molecular modelling. The efficient packing of the aromatic ring of the 1-N-phenyl carboxamide moiety into a hydrophobic sub-site (pocket) in the enzyme´s active site, seems to be responsible for the improved binding affinity in relation to underivatized (-)1-azafagomine and (+)1-azafagomine.We thank FCT for project funding PTDC/QUI/67407/2006 and FCT and FEDER for funding NMR spectrometer Bruker Avance III 400 as part of the National NMR Network. M.N.M. acknowledges the contract research program "Compromisso com a Ciencia" Reference C2008-UMINHO-CQ-03 and access to the Minho University GRIUM cluster