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The acid catalyzed cycloaddition reaction of methyl glyoxylate oxime with cyclopentadiene (CPD) afforded the corresponding aza-Diels–Alder adducts, the endo and exo isomers of (±)-methyl 2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene-3-carboxylates, and as the major product a 1,3-cycloadduct, methyl (1RS,4RS,5RS)-(2-oxa-3-azabicyclo[3.3.0]oct-7-ene)-4-carboxylate. The similar reaction using cyclopentene (CP) provided only the 1,3-cycloadduct methyl (1SR,4RS,5SR)-(2-oxa-3-azabicyclo[3.3.0]octane)-4-carboxylate. The influence of various parameters on the reaction outcome was studied and, based on the results obtained, a mechanism for the formation of both 1,3- and 1,4-cycloadducts is proposed. The structure of all adducts was confirmed by NMR spectroscopic data and/or by X-ray crystallography.

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.

The synthesis of some novel monomeric serine- and tyrosine-based cationic and 4-hydroxyproline-based anionic surfactants, having a long lipophilic alkyl chain directly attached to the nitrogen atom of the amino acid, is described. The most efficient synthetic methodologies were established: reductive amination of the corresponding ‘fatty’ aldehydes, followed by methylation and deprotection (serine and tyrosine) to obtain the cationic surfactants; or reductive amination followed by saponification (4-hydroxyproline) to obtain the anionic ones. All the compounds were obtained in good to excellent yields. An assessment of their micellization properties and surface activity by tensiometry showed fairly good performance levels.