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Biomimetic flavin organocatalysts oxidize nitromethane to formaldehyde and NOx-providing a relatively nontoxic, noncaustic, and inexpensive source for catalytic NO2 for aerobic TEMPO oxidations of alcohols, diols, and ethers. Alcohols were oxidized to aldehydes or ketones, cyclic ethers to esters, and terminal diols to lactones. In situ trapping of NOx and formaldehyde suggest an oxidative Nef process reminiscent of flavoprotein nitroalkane oxidase reactivity, which is achieved by relatively stable 1,10-bridged flavins. The metal-free flavin/NOx/TEMPO catalytic cycles are uniquely compatible, especially compared to other Nef and NOx-generating processes, and reveal selectivity over flavin-catalyzed sulfoxide formation. Aliphatic ethers were oxidized by this method, as demonstrated by the conversion of (-)-ambroxide to (+)-sclareolide.

Benzimidazoles are common in nature, medicines, and materials. Numerous strategies for preparing 2-arylbenzimidazoles exist. In this work, 1,2-disubstituted benzimidazoles were prepared from various mono- and disubstituted ortho-phenylenediamines (OPD) by iron-catalyzed oxidative coupling. Specifically, O2 and FeCl3·6H2O catalyzed the cross-dehydrogenative coupling and aromatization of diarylmethyl and dialkyl benzimidazole precursors. N,N'-Disubstituted-OPD substrates were significantly more reactive than their N,N-disubstituted isomers, which appears to be relative to their propensity for complexation and charge transfer with Fe3+. The reaction also converted N-monosubstituted OPD substrates to 2-substituted benzimidazoles; however, electron-poor substrates produce 1,2-disubstituted benzimidazoles by intermolecular imino-transfer. Kinetic, reagent, and spectroscopic (UV-vis and EPR) studies suggest a mechanism involving metal-substrate complexation, charge transfer, and aerobic turnover, involving high-valent Fe(IV) intermediates. Overall, comparative strategies for the relatively sustainable and efficient synthesis of 1,2-disubstituted benzimidazoles are demonstrated.

N-Alkyl and N-aryl-isoindolinones were prepared by a dioxane-mediated oxidation of isoindoline precursors. The transformation exhibits unique chemoselectivity for isoindonlines. A chiral tertiary (3°)-benzylic position was not racemized during oxidation, and methyl indoprofen was prepared by late stage oxidation. Mechanistic studies suggest a selective H atom transfer, which avoids many known oxidation (by-)products of isoindolinones.

Benzimidazoles are common in nature, medicines, and materials. Numerous strategies for preparing 2-arylbenzimidazoles exist. In this work, 1,2-disubstituted benzimidazoles were prepared from various mono- and disubstituted

A mild, operationally simple, and single-step transition-metal-free protocol for the synthesis of enantiomerically pure (R)-(+)-2'-amino-1,1'-binaphthalen-2-ol (R-NOBIN) from (R)-(+)-1,1'-binaphthyl-2,2'-diamine (R-BINAM) is reported. The one-pot conversion proceeds with good yield and shows no racemization. The hydroxyl on the R-NOBIN product was shown to have come from water in the reaction medium via an H2(18)O study. The correct value of the specific rotation of R-NOBIN was reported.