(Diacetoxyiodo)benzene‐Mediated Oxygenation of Benzylic C(sp³)–H Bonds with N‐Hydroxyamides at Room Temperature

Abstract

A new, metal‐free method for the formation of C(sp3)–O bonds was established by PhI(OAc)2‐mediated oxygenation of benzylic C(sp3)–H bonds with N‐hydroxyamides at room temperature, in which the C(sp3)–H oxidation is activated by a polyflurophenylamide group.

Benzylic C(sp3)–H Functionalization for C–N and C–O Bond Formation via Visible Light Photoredox Catalysis

“…Although significant advances have been made in this area by directing group strategies using transition metal catalysis, a major limitation remains the choice of appropriate directing group and its removal . Another popular approach in this area has been the oxidative nondirected C­(sp 3 )–H bond functionalization using transition metal , PhI­(OAc) 2, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and iodoarene as an oxidant; however, this protocol requires an adjacent heteroatom. Recently, oxidative cross-dehydrogenative couplings (CDC) under metal free conditions using oxidants such as DDQ, hypervalent iodine, and n -Bu 4 NI/TBHP have also been reported for C–C and C–N bond forming reactions (Scheme ).…”

Hypervalent iodine compounds for anti-Markovnikov-type iodo-oxyimidation of vinylarenes

“…Based on the literature data describing the formation of the phthalimide- N -oxyl radical (PINO) from NHPI under the action of PhI(OAc) 2 [ 34 , 55 , 59 , 76 – 77 ], and based on information about the reaction of the PINO radical with styrenes [ 45 ] and interaction of benzyl radicals with iodine [ 78 – 79 ], a mechanism for the reaction of iodo-oxyimidation of styrenes under the action of the NHPI/I 2 /PhI(OAc) 2 system was proposed ( Scheme 3 ).…”

Metal-Free Cross-Dehydrogenative C–O Coupling of Carbonyl Compounds with N-Hydroxyimides: Unexpected Selective Behavior of Highly Reactive Free Radicals at an Elevated Temperature

“…57 Geminal bis-tert-butylperoxides (runs 4 and 5), dibenzoyl peroxide (run 6), and t-BuOOH (runs 7 and 8) afforded the target C−O coupling product 3aa in 20−38% yield. Using MCPBA 58 (run 9) and PhI(OAc) 2 14,17,19 (run 10), known as effective oxidants for the generation of phthalimide-N-oxyl radicals from NHPI even at room temperature, gave 3aa in low yields (10−26%). Thus, it is likely that the gradual generation of phthalimide-N-oxyl radicals at high temperature is desirable.…”