Palladium catalyzed synthesis of highly substituted naphthalenes via direct ring construction from amides with alkynes

Abstract

The direct ring construction of amides with alkynes catalyzed by palladium acetate with cheap oxidant under an air atmosphere has been realized. A variety of novel highly substituted naphthalenes 3a-3l have been prepared chemo- and regioselectively in 55-97% yields under mild conditions. Product 3j emits intense blue luminescence peaked at 435 nm with a good blue purity.

Chemicals from Alkynes with Palladium Catalysts

“…21 N-Arylated acetamides have also been used as arene counterparts in this reaction leading to naphthalenes, using K 2 S 2 O 8 as oxidant in the presence of p-toluenesulfonic acid in toluene as solvent at 80 ºC. 22 In addition, 2-phenylbenzoic acids have been annulated with disubstituted alkynes in a decarboxylative approach catalyzed by Pd(OAc) 2 (10 mol%), 23 using acridine as ligand (50 mol%) and silver carbonate as oxidant, in DMF at 140 ºC, as exemplified in Scheme 6 with the annulation of acid 10…”

Dehydrogenative Heck Annelations of Internal Alkynes

“…19 Consequently, they did not comment on the cause of the different results (compare Equations 8 and 29). The differences are probably due to the coordination environment of the palladium intermediates.…”

“…Miura, Satoh and their research team also attempted the DHA of diphenylacetylene with benzofuran and benzothiophene, but these couplings hardly proceeded, leading to no more than 10% yield of the expected compounds (Equation 19). 32 In contrast, Jiao's experimental conditions were suitable for 3-phenylbenzofuran (Equation 20) and 2,2′-bibenzofuran (Equation 21).…”

“…19 The coupling occurred effectively at 80°C in the presence of p-toluenesulfonic acid, and regeneration of the palladium(II) catalyst by potassium persulfate or benzoquinone, the former being used to establish the scope of the procedure because of its lower Ph Ph Ph Ph R 1 = R 2 = R 3 = R 4 = H (17%); R 1 = R 4 = Me, R 2 = R 3 = H (60%) R 1 = R 4 = Et, R 2 = R 3 = H (35%); R 1 = n-Bu, R 2 = R 3 = H, R 4 = Me (27%) R 1 = R 3 = Me, R 3 = R 4 = H (43%); R 1 = R 2 = R 3 = Me, R 4 = H (52%) R 1 = R 2 = R 4 = Me, R 3 = H (50%); R 1 = R 4 = Me, R 2 = Cl, R 3 = H (16%) R 1 = OMe, R 2 = R 4 = Me, R 3 = H (47%); R 1 = R 3 = Me, R 2 = OMe, R 3 = H (52%) (excess)…”

Enantioselective synthesis of planar chiral ferrocenes via palladium-catalyzed annulation with diarylethynes

“…Cui, Wu and their co-workers recently reported a Pd-catalyzed dehydrogenative annulation of N,N -dimethylaminomethylferrocene in a racemic form [58–66]. To test our hypothesis, we decided to turn such a Pd-catalyzed direct coupling of N,N -disubstituted aminomethylferrocenes with diarylethyne into an enantioselective reaction.…”