Highly practical oxidation of benzylic alcohol in continuous-flow system with metal-free catalyst

A two-step continuous flow synthesis of amides from alcohol using a metal-free catalyst

“…At the outset, a model reaction of benzyl alcohol 1a and morpholine 2a to form benzoyl morpholine 3aa was chosen to identify the reaction system. As we had achieved the optimized conditions of benzyl alcohol to aldehyde, 29 which was the rst step in this study, we would mainly optimize the second step according to the rst step of this reaction. And the results of the optimization of the reaction conditions were summarized in Table 1.…”

“…The mechanism of oxidative amidation of alcohol with amine can be divided into two steps (Scheme 2). 29 Initially, Br À was oxidized to form the hypobromous acid in the presence of acid and hydrogen peroxide. The generated hypobromous acid subsequently reacted with the corresponding hydroxyl group to form the hypobromite intermediate, which yielded the corresponding carbonyl compounds via a-hydrogen elimination.…”

“…Our group has researched the oxidation of alcohol to aldehyde in a continuous ow reactor with metal-free catalyst. 29 In the process, we used H 2 O 2 /NaBr/H + system as oxidant to oxidize benzyl alcohol to aldehyde, which could react with amines to form amides in the presence of an oxidant. Then we designed a two-step continuous ow reactor system, as shown in Fig.…”

Copper(II)-Catalyzed Selective CAr-H Bond Formylation: Synthesis of Dialdehyde Aniline

“…It will be more difficult to synthesize aminobenzaldehydes in one step. A common practice is to generate the amino group and formyl group in different reactions, including the oxidation of the methyl group to the formyl group first and then the reduction of the nitro group to the amino group ( Scheme 2B ) ( Wheeler., 1958 ; Kijima et al, 1984 ; Dai et al, 2011 ), the reduction of the nitro group to the amino group first and then the oxidation of the alcohol group to the formyl group ( Scheme 2C ) ( Sorkin and Hinden., 1949 ; Liu et al, 2015 ), and the addition of the formyl group to the BOC-protected aniline first and then the deprotection of the protected amino group ( Scheme 2D ) ( Ma et al, 2002 ). In addition, a couple of small molecules have been studied as the formyl source for the construction of heterocyclic aromatic aldehydes, such as dimethyl sulfoxide ( Scheme 2E ) ( Zhang et al, 2014 ; Suvam et al, 2021 ), N, N-dimethylformamide ( Koeller and Lellouche., 1999 ; Tang and Shi., 2008 ; Khadka et al, 2012 ; Badalyan et al, 2014 ; Popov et al, 2019 ), and carbon monoxide (Schoenbe et al, 1974; Klaus et al, 2005; Sergeev et al, 2008).…”

Metal‐Free and Selective Oxidation of Benzylic Alcohols to Aromatic Aldehydes by Hexachloroacetone

“…In recent years, several strategies using different complex reagents and modified conditions have also been reported such as Bi 24 O 31 Br 10 (OH) δ with Active Lattice Oxygen, O 2 /amphiphilic resin‐dispersion of palladium nanoparticles, Au−Cu/SiO 2 , Ru(PPh 3 )(OH)‐salen complex, [Ru(bbp)(pydic)], Ag‐NHC complex, H 2 O 2 /Br — /H + , [Cu(MeCN) 4 ]OTf, Au−Pd/TiO 2 /O 2 /H 2 , 2‐azaadamantane N ‐oxyl/Cu, and vanadium Oxide Supported on Metal‐Organic Frameworks …”