Efficient photolytic C–H bond functionalization of alkylbenzene with hypervalent iodine(iii) reagent

Abstract

A practical approach to radical C-H bond functionalization by the photolysis of a hypervalent iodine(iii) reagent is presented. The photolysis of [bis(trifluoroacetoxy)iodo]benzene (PIFA) leads to the generation of trifluoroacetoxy radicals, which allows the smooth transformation of various alkylbenzenes to the corresponding benzyl ester compounds under mild reaction conditions.

A unified photoredox-catalysis strategy for C(sp3)–H hydroxylation and amidation using hypervalent iodine

“…While a number of methods for oxidation of benzylic methylene groups to ketones have been developed, 22 practical methods for C–H hydroxylation of these methylene groups to benzyl alcohols are sparse. 23 As shown in Scheme 3 , we subjected 4-ethylphenyliodide to our standard C–H hydroxylation conditions with PFBl-OH 17 , and obtained the alcohol product 37 in 40% yield along with 22% of ketone 37′ and other unidentified by-products. We were delighted to find that use of 2 equiv.…”

Palladium on Carbon‐Catalyzed Benzylic Methoxylation for Synthesis of Mixed Acetals and Orthoesters

“…[1][2][3][4][5][6][7][8][9][10][11] Althought he acid-catalyzed transacetalizationo fasymmetrical acetal [ÀCH(OR 1 ) 2 ]w ith an alcohol( R 2 OH) is generallya dopted to produce the corresponding mixed acetal [ÀCH(OR 1 )(OR 2 )] as as imple preparation method, the avoidanceo ft he overreaction into another symmetrical acetal [ÀCH(OR 2 ) 2 ]i sg enerally difficult. [1][2][3][4][5][6][7][8][9][10][11] Althought he acid-catalyzed transacetalizationo fasymmetrical acetal [ÀCH(OR 1 ) 2 ]w ith an alcohol( R 2 OH) is generallya dopted to produce the corresponding mixed acetal [ÀCH(OR 1 )(OR 2 )] as as imple preparation method, the avoidanceo ft he overreaction into another symmetrical acetal [ÀCH(OR 2 ) 2 ]i sg enerally difficult.…”

“…[1][2][3][4][5][6][7][8][9][10][11] Althought he acid-catalyzed transacetalizationo fasymmetrical acetal [ÀCH(OR 1 ) 2 ]w ith an alcohol( R 2 OH) is generallya dopted to produce the corresponding mixed acetal [ÀCH(OR 1 )(OR 2 )] as as imple preparation method, the avoidanceo ft he overreaction into another symmetrical acetal [ÀCH(OR 2 ) 2 ]i sg enerally difficult. [2] Although direct alkoxylation reactions of the benzylic positions of the benzyl ether derivatives using as toichiometrico xidant (e.g., tert-butyl peroxide (TBHP), [3] 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), [4] bis(trifluoroacetoxy)iodobenzene, [5] or nitric oxide/N-hydroxyphthalimide (NHPI) [6] )c ould provide mixed acetals,t he applicable substrates were quite limited. [2] Although direct alkoxylation reactions of the benzylic positions of the benzyl ether derivatives using as toichiometrico xidant (e.g., tert-butyl peroxide (TBHP), [3] 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), [4] bis(trifluoroacetoxy)iodobenzene, [5] or nitric oxide/N-hydroxyphthalimide (NHPI) [6] )c ould provide mixed acetals,t he applicable substrates were quite limited.…”

Decarboxylative sp3 C–N Coupling via Dual Copper/Photoredox Catalysis

“…to generate a carboxyl radical, which upon CO 2 extrusion [29][30][31][32] would produce desired alkyl radical 9, while reconstituting the ground state photocatalyst 1. At this stage, we anticipated that copper(II)-amido complex 4 would capture alkyl radical 9 to form copper(III) complex 10, which upon reductive elimination 33 would forge the desired fragment-coupled sp 3 C-N bearing adduct 12 and regenerate copper(I) catalyst 3.…”