Structure and Conformation of Novel BODIPY Ugi Adducts.

Two novel BODIPY-Ugi (boron dipyrromethene) adducts exhibit peculiar room temperature (T=20 °C) H-1 NMR spectra in that several protons located at the aromatic aniline-type ring are lost in the baseline. This observation revealed the existence of a dynamic conformational process where rotation around the C-N bond is hindered. Variable-temperature H-1 and C-13 NMR spectroscopic analysis confirmed this conclusion; that is, low-temperature spectra show distinct signals for all four aromatic protons below coalescence, whereas average signals are recorded above coalescence (T=+120 °C).

Novel Methodologies for Chemical Activation in Organic Synthesis under Solvent-Free Reaction Conditions.

One central challenge for XXI century chemists is the development of sustainable processes that do not represent a risk either to humanity or to the environment. In this regard, the search for more efficient and clean alternatives to achieve the chemical activation of molecules involved in chemical transformations has played a prominent role in recent years. The use of microwave or UV-Vis light irradiation, and mechanochemical activation is already widespread in many laboratories.

One-Pot Lipase-Catalyzed Enantioselective Synthesis of (R)-(-)-N-Benzyl-3-(benzylamino)butanamide: The Effect of Solvent Polarity on Enantioselectivity.

The use of the solvent engineering has been applied for controlling the resolution of lipase-catalyzed synthesis of β-aminoacids via Michael addition reactions. The strategy consisted of the thermodynamic control of products at equilibrium using the lipase CalB as a catalyst. The enzymatic chemo- and enantioselective synthesis of ()-(-)--benzyl-3-(benzylamino)butanamide is reported, showing the influence of the solvent on the chemoselectivity of the -Michael addition and the subsequent kinetic resolution of the Michael adduct; both processes are catalyzed by CalB and both are influenced by the nature of the solvent medium.

Asymmetric Michael Addition Organocatalyzed by α,β-Dipeptides under Solvent-Free Reaction Conditions.

The application of six novel α,β-dipeptides as chiral organocatalysts in the asymmetric Michael addition reaction between enolizable aldehydes and -arylmaleimides or nitroolefins is described. With -arylmaleimides as substrates, the best results were achieved with dipeptide as a catalyst in the presence of aq. NaOH.