Photocatalyzed Intramolecular [2+2] Cycloaddition of N-alkyl-N-(2-(1-arylvinyl)aryl)cinnamamides.

N -Alkyl- N -(2-(1-arylvinyl)aryl)cinnamamides are converted into natural product inspired scaffolds via iridium photocatalyzed intramolecular [2+2] photocycloaddition. The protocol has a broad substrate scope, whilst operating under mild reaction conditions.  Tethering four components forming a trisubstituted cyclobutane core builds rapidly high molecular complexity. Our approach allows the design and synthesis of a variety of tetrahydrocyclobuta[ c ]quinolin-3(1 H )-ones, in yields ranging between 27-99%, and with excellent regio- and diastereoselectivity. Moreover, it was also demonstrated that the intramolecular [2+2]-cycloaddition of 1,7-enynes - after fragmentation of the cyclobutane ring - leads to enyne-metathesis-like products.