6πe⁻ versus 8πe⁻ Electrocyclization of 1-Aryl- and Heteroaryl-Substituted (1Z,3Z)-1,3,5-Hexatrienes: A Matter of Aromaticity

Peri selectivity of the electrocyclization of 1-aryl- and heteroaryl-substituted (1Z,3Z)-1,3,5-hexatrienes, obtained by Ru-catalyzed linear coupling of 1,6-diynes to Z-propenyl(hetero)arenes, can be efficiently modulated depending on the aromaticity of the (hetero)arene: 1,3,5-hexatrienyl(hetero)arenes give 8πe⁻ electrocyclization with the exception of 1,3,5-hexatrienylbenzenes, which give 6πe⁻ electrocyclization.