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The reactivity of the ynamide tert-butyl N-ethynyl-N-phenylcarbamate (1) in the 1,3-dipolar cycloaddition (1,3-DC) with C-carboxymethyl-N-phenylnitrilimine was investigated. This [3+2] cycloaddition affords the 5-amino pyrazole as a single regioisomer. The obtained cycloadduct has been activated at the 4-position of the pyrazole ring through bromination and subsequently coupled with a phenyl group under Pd catalysis. A detailed computational study has been performed to fully explain the complete regioselectivity observed.

1,3-Dipolar cycloadditions of C-carboxymethyl-N-arylnitrile imines with substituted acetylenes bearing thiol or sulfone groups were studied. The sulfur controls the regiochemistry of the reaction, and this protocol was applied to the synthesis of ring-fused thieno[2,3-c]pyrazoles.

The cyanobis(dibenzylamino)borane-mediated transformation of chiral aldehydes into the corresponding α-amino nitriles is described. Starting from these compounds short synthetic routes can be envisaged for obtaining diastereomerically pure functionalized 1,2-diamines and hydroxylated α-amino acids that are of interest as core key units of biologically active substances or as potential ligands for asymmetric catalysis. The stereochemical outcome of the aminative cyanation reaction is discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Several new ligands featuring a rigid three ring skeleton have been prepared for the first time following a modular approach. Chirality has been introduced by use of an oxazoline moiety fused with a cyclopenta[b]thiophene backbone. The efficiency and stereochemical impact of these ligands on the copper-catalyzed enantioselective addition of Et2Zn to chalcone was examined and enantiomeric excesses up to 79% were achieved using the ligand (R,R)-16 substituted with a methyl group at the cyclopenta moiety. Computational and ESI-mass spectral studies show that these new compounds behave as monodentate ligands towards Cu+. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)