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Speaker: Prof. G. Sekar
Indian Institute of Technology Madras,
Chennai-600036, INDIA
Title: "Asymmetric Domino Synthesis of Chiral Heterocyclic Compounds using Organocatalysts."
Day and Date: Monday, June 24, 2024
Time: 3.00 PM.
Venue: Room no. 350, Chemistry Department Second floor, Annex
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Hosted by Prof. Ramaswamy Murugavel
Abstract 1,4-Thiazine, benzo[1,4]thiazine, pyrrolo[1.4]thiazine and their polyhydro derivatives are privileged
heterocyclic core present in many bioactive molecules.1-2 Over the past decades, several methods have
been developed to construct achiral/racemic pyrrolo[1,4]thiazine derivatives.3 Recently, Feng et al.
reported the first synthesis of chiral hydropyrrolo-thiazoles and [1,4]thiazine derivatives using chiral
N,N´-dioxide/metal catalysts.4 Herein, we report a proline-derived organocatalytic enantioselective
synthesis of pyrrolo[1,2-d][1,4]thiazine-2-carbaldehydes using domino 1,3-dipolar
cycloaddition/rearrangement of benzothiazolium salt with α,β-unsaturated aldehyde. This domino
process produced fluorescent emissive chiral molecules with three contiguous stereocenters, having one
chiral quaternary center in a single step. This strategy was extended to the stereoselective one-pot
synthesis of chiral N-phenyl thioether-tethered tetrasubstituted dihydropyrrole-3-carbaldehydes via 1,3-
dipolar cycloaddition/rearrangement, followed by ring-opening/C-S bond formation (Scheme 1).