Indian Institute of Technology Delhi
Synthesis of N-Heterocycles via 1,2-Migration of Boron-ate Complexes
Dr. Santanu Panda
Department of Biochemistry, UT-Southwestern Medical Centre, Dallas
Date: September 22nd 2017 (Friday)
Time: 4 PM
Venue: Committee Room, Chemistry Department, 6th Floor
Pyridine, piperidine, indoles and indolines are prized heterocycles in drug discovery and natural products research. We have been interested in developing multicomponent coupling reactions to form nitrogen heterocycles. We envisioned a novel method for the preparation of substituted pyridines, dihydropyridines and piperidines starting from the pyridine boronic ester. The reaction of organometallic reagent with pyridine boronic ester generates the boron ate complex, which participates in a 1,2-migration upon activation of the pyridine with an acid chloride (Scheme 1a). The dihydropyridine intermediate allows access to a number of valuable substituted pyridines, dihydropyridines, and piperidines. We hypothesized that the reactivity pattern of pyridine boron ate complex could be extended to indole 2-boron ate complex to provide substituted indoles and indolines. Indeed, by using catalytic ((S)-BINAP)PdCl2, allylic acetates and boronate esters, we are able to access the optically active indoline boronate esters, which were converted to various 2,3-disubstituted optically active indoles after oxidation or to the corresponding indolines with three new, contigious stereocenters after deborylation (Scheme 1b).
All are cordially invited to attend.