Cascade MHAT Radical Cyclopentannulation of Skipped Enyne to Access Highly Functionalized Carbocycles

Abstract An iron-mediated metal-hydride hydrogen atom transfer (MHAT) radical cyclization cascade has been developed for the efficient construction of highly functionalized carbocyclic frameworks. This versatile [3+2] cyclopentannulation strategy starting from skipped enynes provides rapid access to a broad range of alkylidene cyclopentanes/cyclopentenes. Termination of this cascade with various radical trapping agents allows efficient construction of annulated products via successive C–H/C–C/C–C/C–X bond (X = C, H, S, Se, Te, I) formation. The method allows an expeditious entry into diquinanes, angular triquinanes with 4 quaternary carbons (3 contiguous) and substituted cyclopentadienes, all amenable to complex carbocycle synthesis.