Marcello Rasparini

Ugi and Passerini reactions of biocatalytically derived chiral aldehydes: application to the synthesis of bicyclic pyrrolidines and of antiviral agent telaprevir.

Lipase mediated desymmetrization of a meso-diol (1,2-cyclopentanedimethanol) allows the synthesis of both enantiomers of some chiral aldehydes, whose behavior in Passerini and Ugi reactions has been explored. Exploiting these two complementary multicomponent reactions and coupling them with a subsequent cyclization process, we observed that 6 out of all 8 possible stereoisomers of peptidomimetic pyrrolidines can be obtained in good yields. The potential of these protocols has been proved by the development of a new efficient synthesis of antiviral drug telaprevir.

Asymmetric synthesis of (R)-(−)-chlozolinate through a chemoenzymatic procedure

Abstract A new asymmetric synthesis of (R)-chlozolinate 1, an important antifungal agent, based on the enzymatic asymmetrization of diethyl 2-benzyloxy-2-methylmalonate, is reported.

Intramolecular transamidation of β-lactams as a means for the enzymatic control of ring opening: Effect of substituents on the rate of reaction

Abstract A series of simple monocyclic β-lactams bearing side-chains, containing amino groups, have been synthesized, and the rate of their intramolecular transamidation studied. Protection of the amino group with an enzymatically cleavable group, allows us to selectively control the ring enlargement process.

Anti-Selective Organocatalytic Michael Addition between Phenylacetaldehyde and Nitrostyrene.

Using the reaction between phenylacetaldehyde and nitrostyrene catalyzed by pyrrolidine as a simple model, we have studied the diastereochemical outcome of the organocatalytic Michael reactions between benzylic aldehydes and nitrostyrenes. We found that the anti adduct was obtained in high yield and diastereoselection as was demonstrated by the X-ray structure of the product. In situ NMR studies showed a different reaction pathway when compared to aliphatic aldehydes that yield the syn adduct as major isomer.