Substituent Effects On Intramolecular Epoxide Cyclizations That Can Competitively Occur at Aromatic or Double Bond Positions¹

Abstract

The effects of substituents on epoxides that can competitively cyclize at either a double bond or aromatic position were determined. Adding a group that would stabilize the transition state of the double bond cyclization of an epoxide that underwent predominantly aromatic cyclization increased the relative amount of the former pathway, but not dramatically. Adding a strong activating substituent to the aromatic group of an epoxide that underwent predominantly double bond cyclization increased the relative amount of aromatic cyclization, but a complex product mixture was obtained. An explanation of the behavior observed is presented.

Samarium Triflate-Catalyzed Halogen-Promoted Friedel−Crafts Alkylation with Alkenes

“…1,4-Conjugate addition of arenes to electron-deficient alkenes are mostly limited to indoles as arenes . Ring-opening of epoxides with arenes is also known in the literature . However, to the best of our knowledge, intermolecular F-C alkylation with alkenes via halonium ions has not been reported.…”

Transformation of oxiranes into other oxygen-containing heterocyclic systems

“…Taylor et al [47,48] [50]. Following an analogous procedure, a series of disubstituted oxepanes was synthesized [51].…”

Fe(OTf) 3 -catalysed Friedel–Crafts reaction of benzenoid arenes with α,β-unsaturated carbonyl compounds: easy access to 1,1-diarylalkanes

“…in standard protocols to free the by-products from arylated products. Three-member cyclic and reactive intermediates, such as epoxides [24][25][26][27][28][29][30][31][32], aziridines [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] and halonium ions [48][49][50][51][52][53], or other unstable intermediates [54][55][56][57][58] derived in situ from alkenes have also been found as potential electrophiles to afford functionalized Friedel-Crafts alkylated products. Another important strategy to afford 1,1diarylalkanes is Friedel-Crafts-type hydroarylation reaction with olefins.…”