Science of Synthesis

Chan, W.-W.; Yu, W.-Y., Science of Synthesis: Catalytic Transformations via C—H Activation, (2015) 2, 111.

A [bis(trifluoroacetoxy)iodo]benzene-mediated cross dehydrogenative coupling of aldehydes to heterocycles such as isoquinolines, pyridines, benzothiazole, and caffeine has been achieved at room temperature in the presence of trimethylsilyl azide (‌Scheme 9‌).[‌41‌] The acylation reaction generally occurs at the position ortho to the nitrogen atom. The scope of aldehydes is very broad; various aliphatic, aromatic, and heteroaromatic aldehydes are effectively coupled with the N-heterocycles. Several examples of alkaloid synthesis via direct radical coupling of benzaldehydes and heterocycles are demonstrated. However, employment of benzaldehydes bearing electron-withdrawing groups such as fluoro and chloro at the ortho and meta positions results in poor yields; reactions of the para-substituted analogues are more successful.

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References