Short and efficient route toward α-substituted N-arylazetidines from acetanilides via Mitsunobu reaction

N-Arylazetidines are efficiently obtained in a three-step procedure, providing a wide diversity of derivatives on multigram scale with overall yields of 21–55%. Cheap or easily available acetanilides are used in an adapted aldolization with aldehydes, furnishing β-hydroxyamides with an 81% average yield over 21 examples. Special Mitsunobu conditions have been developed to ensure the cyclization of these hydroxyamides, giving β-lactams with an 73% average yield over 16 examples. A reduction then provided the N-arylazetidines in high yields.     

Straightforward Synthesis of 5‐Bromopenta‐2,4‐diynenitrile and Its Reactivity Towards Terminal Alkynes: A Direct Access to Diene and Benzofulvene Scaffolds

The high‐yielding synthesis of 5‐bromopenta‐2,4‐diynenitrile (BrC₅N) was achieved for the first time. Its reactivity with triisopropylsilylacetylene and triisopropylsilylbutadiyne in the presence of copper and palladium as co‐catalysts and diisopropylamine was evaluated. It revealed an unprecedented cascade reaction leading to a diene in one case and to a benzofulvene in the other case, with a unique structure. Both of them were characterized by X‐ray crystallography, among other techniques. The mechanism of the reaction leading to the diene was investigated experimentally. Theoretical calculations at the DFT level suggest that the mechanism leading to the benzofulvene relies on a hexa‐dehydro Diels–Alder (HDDA)‐type of mechanism. This work constitutes an example of an unanticipated reactivity leading to an important increase of chemical complexity.     

A general approach to access 5,6-dihydroindolo-naphthyridine ring system

We report a general approach for the synthesis of 5,6-dihydroindolo-naphthyridine ring system via an intramolecular cyclization of the indole NH to an alkene moiety as the key step.