Kunal Keskar

The First Well‐Defined Silver(I)‐Complex‐Catalyzed Cycloaddition of Azides onto Terminal Alkynes at Room Temperature

The copper(I)-catalyzed Huisgen dipolar cycloaddition of terminal alkynes 1 with azides 2 to yield 1,4and 1,4,5-substituted 1,2,3-triazoles 3 (azide–alkyne cycloaddition; AAC reaction) has been transformed in recent years, since its description as the prototype “click” reaction, to become a general process with applications in diverse areas ranging from functional materials to biological chemistry. The generally accepted mechanism for the reaction, outlined in Scheme 1, involves a stepwise process initiated through generation of a copper(I) acetylide complex I, which complexes to the azide 2, undergoes the cycloaddition, generating a metalated triazole III, which is then protonated to yield the product 3, regenerating the catalyst.

Isolation of flavonoids from the heartwood and resin of Prunus avium and some preliminary biological investigations

An investigation of the constituents in heartwood and resin of Prunus avium is reported. A mini-library of structurally diverse flavanones and flavones was screened for human cytochrome P450 1A1, 3A4 and 19 (aromatase) inhibition, and for antifungal activity against a panel of pathogenic fungi. The defensive role of these natural plant flavonoids as antifungal phytoalexins and phytoanticipins is discussed.

High Yielding Synthesis of Carboranes Under Mild Reaction Conditions Using a Homogeneous Silver(I) Catalyst: Direct Evidence of a Bimetallic Intermediate†

Methods used to prepare functionalized carboranes generally require heating to high temperatures, and thus limits the range of derivatives which can be prepared directly from alkynes. We show here that by using a homogeneous silver(I) catalyst it is now possible to prepare carboranes in good to excellent yield at temperatures below 40 °C, including at room temperature. The process is general and provides an important new synthetic strategy for the preparation of functionalized boron clusters.

Synthesis of the cyanobacterial metabolite nostodione A, structural studies and potent antiparasitic activity against Toxoplasma gondii

A total synthesis of the cyanobacterial natural product nostodione A is reported involving a convergent, diversity-oriented route, enabling the assembly of a mini-library of structural analogues. The first single crystal X-ray structural determination on a member of this series is reported along with SAR studies identifying potent inhibitors of invasion and replication of the parasitic protozoan Toxoplasma gondii.

Discovery of a new class of cinnamyl-triazole as potent and selective inhibitors of aromatase (cytochrome P450 19A1).

Synthesis of a novel class of natural product inspired cinnamyl-containing 1,4,5-triazole and the potent inhibition of human aromatase (CYP 450 19A1) by select members is described. Structure-activity data generated provides insights into the requirements for potency particularly the inclusion of an aryl bromide or chloride residue as a keto-bioisostere.