α-Sulfonyl Radical Initiated Intramolecular Tandem Radical Cyclization: Stereochemistries of a Pair of Doubly Cyclized Products

Abstract

Room-temperature single-crystal X-ray structure determinations are recorded for trans-1,2,3,3a,9,9a-Hexahydro-cyclopenta[b]-1-benzothiapyran-4,4-dioxide and its 3a-methyl analogue, minor products of the α-sulfonyl radical-initiated intramolecular tandem radical cyclization of H₂C=CH(CH₂)CRBrSO₂Ph (R = H, CH₃), confirming the assigned structures and rigorously establishing the trans relationship at the ring junctions.