Metal‐Free Enantioselective Oxidative Arylation of Alkenes: Hypervalent‐Iodine‐Promoted Oxidative C−C Bond Formation

Abstract

The enantioselective oxyarylation of (E)-6-aryl-1-silyloxylhex-3-ene was achieved using a lactate-based chiral hypervalent iodine(III) reagent in the presence of boron trifluoride diethyl etherate. The silyl ether promotes the oxidative cyclization, and enhances the enantioselectivity. In addition, the corresponding aminoarylation was achieved.

Reactions promoted by hypervalent iodine reagents and boron Lewis acids

“…In 2010, Fujita described the enantioselective oxyarylation of (E)-6-aryl-1-silyloxylhex-3-ene to afford 40 (Scheme 17, top). 52 Different Lewis and Brønsted acids were screened for the cyclisation reaction and BF 3 •OEt 2 was found to be the most efficient. To test the effect of the steric bulk, different silyl groups were employed for the cyclisation reaction with slightly better enantioselectivity being observed with the bulky tertbutyldiphenyl silane (TBDPS) compared to the tert-butyldi- Organic & Biomolecular Chemistry Review methylsilyl ether (TBS) group.…”

Hypervalent iodine-mediated synthesis and late-stage functionalization of heterocycles

“…Meanwhile, Sugimura's team presented an enantioselective intramolecular oxyarylation of (E)-6-aryl-1silyloxylhex-3-ene 276 promoted by lactate-based chiral iodine(III) reagent 277, 278 and 279 in the presence of BF3•OEt2 (Scheme 75). 106 Tricyclic products 280 were obtained in variable yields under metal-free conditions. Further experimental evidences revealed that silyl group as a protecting group accelerates this oxidative cyclization reaction and also contribute for high enantioselectivity.…”

Alkene Difunctionalization Using Hypervalent Iodine Reagents: Progress and Developments in the Past Ten Years

“…In 2016, Fujita and colleagues added a new version of chiral hypervalent iodine-mediated enantioselective oxidative C–C bond formation. The silyloxy-attached internal alkene 151 effectively yielded oxyarylation adduct in the presence of lactate-based chiral iodine 152 and BF 3 ·OEt 2 as a promoter (Scheme 29a) [97]. Another example was reported by Fujita et al in 2017 (Scheme 29b) [98].…”