Ulhas Bhatt

Synthesis of unsaturated lactone moieties by asymmetric hetero Diels–Alder reactions with binaphthol-titanium complexes

Natural products like ratjadone and callystatin A contain an α,β-unsaturated lactone moiety which adds to the biological activity of these compounds. Here we report a rapid and practical access to lactone precursor 3 by an asymmetric hetero Diels–Alder reaction as the key step and its subsequent transformation into a suitable building block 4.

Derivatized oxopiperazine rings from amino acids

Abstract Two routes for the synthesis of derivatized oxopiperazines, which may act as constrained peptide mimics, are reported. The syntheses employ reductive amination and sulfonamide approaches for generating N-allylic amino acid ester derivatives and utilizing them for assembling the ring systems. An aspartame analog was prepared using this methodology.

EFFICIENT SYNTHESIS OF SUBSTITUTED OXOPIPERAZINES FROM AMINO ACIDS

Abstract The synthesis of substituted oxopiperazines, which may act as conformationally constrained peptide mimics, is reported. The synthesis is based on the cyclization of sulfonamide dipeptides with dibromoethane as the 1,2-dielectrophile. Alternatively, these mimetics were prepared via a Mitsunobu reaction.

Synthesis of a Novel Thyrotropin Releasing Hormone (TRH) Analog Incorporating a Piperazin-2-one Ring

The synthesis of a Thyrotropin Releasing Hormone (TRH) analog incorporating a piperazin-2-one ring is described. This conformationally restricted peptidomimetic attempts to retain the key recognition elements of the interaction between TRH and its receptor. The synthesis started from the protected dipeptide 2 and proceeded via the 4-nitrobenzenesulfonyl-activated intermediate 3, which was then cyclized, N-acylated, and deprotected to yield the target compound 1.

In Vitro Testing of a New Substance with Anti-Tumor Activity on Mammalian Cells Using Flow Cytometry

In our work we have shown that ratjadone has an inhibiting effect on tumor cells. It causes a cell cycle arrest in G1-phase through activation of the cyclin dependent kinase inhibitor p21. This effect was observed at nanomolar concentrations.