Metal-free cross-dehydrogenative coupling of aryl aldehydes to give symmetrical carboxylic anhydrides promoted by the TBHP/nBu4PBr system

Size-Driven Inversion of Selectivity in Esterification Reactions: Secondary Beat Primary Alcohols

“…Compound 3b (788 mg, 42%) was obtained as a white solid: mp 71–73 °C; 1 H NMR (400 MHz, CDCl 3 ) δ 8.02 (dd, J = 7.8, 1.8 Hz, 1H, Ar), 7.56 (ddd, J = 9.0, 7.5, 1.8 Hz, 1H, Ar), 7.08–6.96 (m, 2H, Ar), 3.86 (s, 3H, Me) ppm; 13 C­{ 1 H} NMR (101 MHz, CDCl 3 ) δ 161.99, 160.28, 135.32, 133.25, 120.48, 118.38, 112.25, 56.03 ppm; HRMS (EI) m / z [M] + calcd for C 16 H 14 O 5 286.0841, found 286.0831. The 1 H/ 13 C­{ 1 H} NMR spectra are in full agreement with them reported in literature …”

Ti-superoxide catalyzed oxidative amidation of aldehydes with saccharin as nitrogen source: synthesis of primary amides

“…), the corresponding TEMPO adduct 10 was detected and confirmed by LCMS, thus establishing the formation of benzoyl radical that underwent radical coupling in the reaction. On the basis of the above experiments and literature precedence, 11 a plausible catalytic cycle is proposed in Scheme 3 . Initially, combination of acyl radical, generated from aldehyde on oxidation with TBHP, in the presence of Ti catalyst A produces Ti peroxo species B.…”

Latest Advancements in Transition‐Metal‐Free Carbon‐Heteroatom Bond Formation Reactions via Cross‐ Dehydrogenative Coupling

“…[44] Adib et al reported the synthesis of symmetrical carboxylic anhydrides by coupling aryl aldehydes in presence of nBu 4 PBr/ TBHP system using chlorobenzene as solvent at 80 °C for 3 h (Scheme 47). [45] It is noteworthy that irrespective of the position on the aryl ring, EDGs gave moderate to good yields of products, however; EWGs did not furnish the desired anhydrides. Various aldehydes including naphthalene carbaldehyde, cinnamaldehyde and other heteroaromatic aldehydes such as furan-2-carbaldehyde, thiophene-2-carbaldehyde reacted smoothly under the standard conditions.…”