Highly diastereoselective synthesis of aza-diels-alder reaction of danishefsky diene wiht glyoxylate imines

Aza-Diels-Alder reaction is an exceptionally powerful synthetic method for the construction of six-membered nitrogen-heterocycles.[1-3] The reaction of Danishefsky's diene 1 with iminoacetates 2 (imines of glyoxylates) provides a convenient protocol for the synthesis of pipiridone adducts 3 (Scheme 1). In this context, we have performed the synthesis of various cycloadducts, precursors of a wide variety of chiral piperidines with potential use as non-natural amino acids or as precursors of biologically active compounds, including iminosugars (glycomimetics)

Ethyl 2-(Diisopropoxyphosphoryl)-2H-Azirine-3-Carboxylate: Reactions with Activated 1,3-Butadienes

The 12th International Electronic Conference on Synthetic Organic Chemistry session General Organic SynthesisEthyl 2-(diisopropoxyphosphoryl)-2H-azirine-3-carboxylate was generated “in situ” and reacted with a number of 1,3-butadienes. Cycloadducts, or in one case an ensuing rearranged product, were isolated with moderate to good yieldsThe authors thank Fundação para a Ciência e Tecnologia, CIQA-Centro de Investigação em Química do Algarve and Xunta de Galicia for financial support under project 07CSA008203P

Highly diastereoselective synthesis of 2-azabicyclo[2.2.1]hept-5-ene derivatives : bronsted acid catalized aza-diels-alder reaction between cyclopentadiene and imino-acetates with two chiral auxiliaries

The cycloaddition between protonated glyoxylate imines possessing two chiral auxiliaries, N-(S)- or N-(R)-1-phenylethyl and (-)-8-phenylmenthyl or (+)-8- phenylneomenthyl, and cyclopentadiene is described. The absolute configuration of all adducts formed was unequivocally assigned through NMR, specific optical rotation and X-ray data of appropriated derivatives. Experimental results confirm the highly exoselectivity for these aza-Diels–Alder reactions, single adducts being obtained from combinations of (8PM)-(R-PEA) and (8PNM)-(S-PEA).Thanks are due to Fundacao para a Ciencia e Tecnologia (FCT) for financial support given to Faculdade de Ciencias do Porto (project PTDC/QUI/67407/2006) and for financial support through the re-equipment program REDE/1517/RMN/2005

Study based on electronic descriptors of the diastereoselective aza-diels-alder cycloaddition of [(1r)-10-(n,n-diethylsulfamoyl)isobornyl] 2h-azirine-3-carboxylate to e,e-1,4-diacetoxy-1,3-butadiene

Cycloaddition of chiral [(1R)-10-(N,N-diethylsulfamoyl)isobornyl] 2H-azirine-3-carboxylate to E,E-1,4-diacetoxy-1,3-butadiene shows complete diatereoselectivity giving a single cycloadduct (-)-(2S,5R,6R)-6-[(1R)-10-(N,N-diethylsulfamoyl)isobornyloxycarbonyl]-1-azabicyclo[4.1.0]hept-3-ene-2,5-diyldiacetate. Our main objective is to identify electronic/steric parameters capable of describing the observed tendencies of this reaction. The results of the calculations conclude that: even though the steric factors can play an important role at the initial steps of the reaction, at the transition states the behavior of several electronic parameters; like hardness, polarizability, aromaticity, charge transfer, etc is decisive enough to justify the obtained product. Finally, this work summarizes an exhaustive analysis of electronic descriptors and empirical reactivity principles, reaching a definitive and comprehensive explanation to the observed experimental result.Thanks to Fundação para a Ciência e Tecnologia (FCT) for partial financial support (project PTDC/QUI/67407/2006

Methyl 2-diphenyl­phosphor­yloxy-2-aza­bicyclo­[2.2.1]hept-5-ene-3-exo-carboxyl­ate

In the title compound, C20H20NO4P, the dihedral angle between the phenyl rings is 68.52 (7)°. In the crystal structure, the mol­ecules are linked by a weak C—H⋯π(arene) inter­action along [010] involving the phenyl CH group and the phenyl rings. There are no further significant inter­molecular inter­actions

Aza-Diels-Alder versus 1,3-Dipolar Cycloadditions of Methyl Glyoxylate Oxime with Cyclopentadiene

The 12th International Electronic Conference on Synthetic Organic Chemistry session Computational ChemistryThe acid-catalyzed [3+2] and [4+2] cycloadditions between methyl glyoxylate oxime (1) and cyclopentadiene were investigated using various Lewis and/or Bronsted acids at different temperatures in dichloromethane as solvent. Besides the expected new adducts, (±)-methyl [(3-exo)-2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene]-3-carboxylate (2) and (±)-methyl [(3-endo)-2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene]-3-carboxylate (3) a third addict, (±) methyl (1R,4R,5R)-(2-ox-3-azabicyclo[3.3.0]oct-7-ene)-4-carboxylate (4), whose formation can be explained by a concerted 1,3-dipolar cycloaddition, was obtained. Yields and product ratios were found to be more dependent on the catalyst than on the temperature; these results and the stereochemistry of the adducts, confirmed by spectroscopic data (1H and 13C NMR) and by X-ray cycloadditionsThis work was supported by Centro de Investigação em Química of University of Porto. The authors thank the Fundação para a Ciência e Tecnologia (FCT) for financial support of this work under project POCTI/QUI/44471/2002 (Pluri-annual and Programmatic Funding) and for the grant to C. A. D. Sousa (SFRH/BD/31526/2006

(1RS,4RS,5RS)-Methyl 2-(3,5-dinitro­benzo­yl)-2-oxa-3-aza­bicyclo­[3.3.0]oct-7-ene-4-carboxyl­ate

The title compound, C15H13N3O8, comprises two crystallographically independent mol­ecules in the asymmetric unit. In the crystal, intermolecular C—H⋯O hydrogen bonds link the molecules and short C=O⋯π contacts are seen

Synthesis and Antiviral Activities of Novel Purinyl- and Pyrimidinylcarbanucleosides Derived from Indan

The 12th International Electronic Conference on Synthetic Organic Chemistry session Bioorganic Chemistry and Natural ProductsStarting from (±)-trans- and (±)-cis-3-hydroxymethyl-1-indanol, novel 6-substituted purinylcarbanucleoside derivatives of indan (5, 6, 9, 10, 15 and 17) were synthesized through a key coupling reaction with 6-chloropurine under Mitsunobu conditions. Suzuki–Miyaura reactions of the protected 6-chloropurine derivative with different arylboronic acids afforded the corresponding 6-arylpurinylcarbanucleoside derivatives. Finally, three new 5-halouracilcarbanucleosides (19, 20 and 21) were prepared by reaction of uracilcarbanucleoside 18 with different N-halosuccinimides. All of the new analogues were evaluated for antiviral activity against a wide variety of virusesThe authors thank the Xunta de Galicia for financial support of this work under projects PGIDT05PXIB20301PR and 07CSA008203P

Is type of work associated with physical activity and sedentary behaviour in women with fibromyalgia A cross-sectional study from the al-Ándalus project

Objectives To analyse the association between the type of work (productive vs reproductive work) and the levels of physical activity and sedentary behaviour in women with fibromyalgia. Method This cross-sectional study involved 258 women with fibromyalgia from southern Spain. Of them, 55% performed reproductive work (unpaid, associated with caregiving and domestic roles) exclusively, while 45% had productive job (remunerated, that results in goods or services). Physical activity of light, moderate and vigorous intensity in the leisure time, at home, at work, and totally were measured through the leisure time physical activity instrument and with the physical activity at home and work instrument, respectively. Sedentary behaviour was measured by the Sedentary Behaviour Questionnaire. Results After adjusting for age, fat percentage, education level and marital status, the multivariate analysis of covariance model informed the existence of significant differences between type of work groups (p<0.001). Women with productive work engaged in more light physical activity at work (mean difference =448.52 min; 95 % CI 179.66 to 717.38; p=0.001), and total physical activity of light (809.72 min; 535.91 to 1085.53; p<0.001) and moderate (29