Facile Formation of Unexpected [m,6,n]-tricyclic Spiranes via Intramolecular [3+2] Cyclization of Platinum-bound Pyrylium with Alkenes

Abstract

Enynals bearing an olefinic pendant were successfully cyclized via Huisgen-type [3+2] cycloaddition to the tetracyclic Pt-carbene complexes which would undergo insertion into a C-H bond of the beta-position to afford the fused cyclopropane intermediates. Their tandem rearrangement afforded diverse types of spiranes depending on the tethered alkenes of the enynals.