Photochemical Cleavage of Alkynes to (Deuterated) Aldehyde using Bromide

Singh, Amisha (2025) Photochemical Cleavage of Alkynes to (Deuterated) Aldehyde using Bromide. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Amisha Singh (20MS097)) 20MS097_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (4MB)

Abstract

The oxidative cleavage of alkynes represents a fundamental transformation for converting simple feedstock chemicals into synthetically valuable intermediates. However, the high bond dissociation energy of the carbon–carbon triple bond has posed significant challenges to achieving this transformation in a single, efficient step. In this study, we present an alternative strategy that enables the chemoselective oxidative cleavage of aromatic terminal alkynes under visible-light irradiation. This catalyst-free protocol proceeds under mild conditions, exhibits broad functional group tolerance, and offers a sustainable solution to a long-standing synthetic challenge. Using, lithium bromide and oxygen as the C–C bond activator, a catalyst free, organo-photochemical method for the chemo selective oxidation of aryl alkynes is devised. This process presents a wide spectrum of functional group sustainability and exhibits remarkable selectivity towards the cleavage of aromatic C-C triple bonds over comparable aliphatic scaffolds. In the presence of functional groups that are sensitive to oxidation, this method also permits the selectivity of aryl alkynes. The reaction procedure also supports excellent deuteration of aldehyde in situ when paired with a HAT reagent and deuterium oxide. The deuteration is highly selective to the aldehyde site alone in presence of other active sites as well, increasing the effectivity and selectivity of the reaction procedure.

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