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Visible‐Light‐Driven Photocatalyst‐ and Additive‐Free Cross‐Coupling of β‐Ketothioamides with α‐Diazo 1,3‐Diketones: Access to Highly Functionalized Thiazolines

2020; Wiley; Volume: 26; Issue: 36 Linguagem: Inglês

10.1002/chem.202000279

1521-3765

Monish Arbaz Ansari, Dhananjay Yadav, Maya Shankar Singh,

Catalytic C–H Functionalization Methods

A photocatalyst- and additive-free, visible-light-mediated chemoselective domino protocol was devised to access fully substituted thiazoline derivatives from β-ketothioamides and α-diazo 1,3-diketones at moderate temperature in open air. The reaction proceeds through in situ generation of electrophilic carbenes from α-diazo 1,3-diketones by a low-energy blue LED (448 nm), which undergoes selective coupling with nucleophilic β-ketothioamides to give thiazolines by successive formation of C-S and C-N bonds in one stretch. Notably, the benign and clean conditions, operational simplicity, sustainability, 100 % carbon economy, high yields, and wide functional-group tolerance are further attributes of the strategy. A mechanistic rationale for this cascade reaction sequence is well supported by control experiments.