Reaction of (<i>Z</i>)-1-Aryl-3-hexen-1,5-diynes with Sodium Azide: Synthesis of 1-Aryl-1<i>H</i>-benzotriazoles

A novel tandem cascade reaction involving 1,3-dipolar cycloaddition reaction, anionic cyclization, and sigmatropic rearrangement for the synthesis of 1-aryl-1H-benzotriazoles 2 and 3 was accomplished by treatment of the (Z)-1-aryl-3-henen-1,5-diynes (1) with sodium azide in DMF or DMSO at 80 °C for 12 h and gives 65−91% yields

A Very Facile S_NAr Reaction with Elimination of Methoxide

A Very Facile SNAr Reaction with Elimination of Methoxid

Palladium-Catalyzed Annulation of 2-(1-Alkynyl)biphenyls with Aryl Iodides to Disubstituted Methylidenefluorenes.

Palladium-Catalyzed Annulation of 2-(1-Alkynyl)biphenyls with Aryl Iodides to Disubstituted Methylidenefluorenes

Transition Metal-Catalyzed Cascade Cyclization of Aryldiynes to Halogenated Benzo[<i>b</i>]naphtho[2,1‑<i>d</i>]thiophene Derivatives

Treatment of 2-(2-(2-(2-substituted ethynyl)­phenyl)­ethynyl)­thioanisoles (<b>1</b>) with 5 mol % of Ph₃PAuCl/AgSbF₆ and 2 equiv of NIS at refluxing CH₂Cl₂ gave iodo-substituted benzo­[<i>b</i>]­naphtho­[2,1-<i>d</i>]­thiophene (<b>6</b>) in good yields. Chloro- and bromo-substituted benzo­[<i>b</i>]­naphtho­[2,1-<i>d</i>]­thiophene derivatives (<b>8</b> and <b>9</b>) were also generated by treating compound <b>1</b> with 5 mol % of PdX₂ and 3 equiv of CuX₂ at refluxing THF

Palladium-Catalyzed Annulation of 2-(1-Alkynyl)biphenyls with Aryl Iodides to Disubstituted Methylidenefluorenes.

Palladium-Catalyzed Annulation of 2-(1-Alkynyl)biphenyls with Aryl Iodides to Disubstituted Methylidenefluorenes

Double Anionic Cycloaromatization of 2-(6-Substituted-3-hexene-1,5-diynyl)benzonitriles Initiated by Methoxide Addition

Treatment of 2-((3Z)-undecene-1,5-diynyl)benzonitrile with 5 equiv of sodium methoxide in refluxing methanol for 16 h gave 1-pentyl-6-methoxyphenanthridine in 12% yield, 1-pentyl-6-phenanthridone in 6% yield, and 2-(2-pentyl-6-methoxyphenyl)benzonitrile in 4% yield. Under the same reaction conditions, methanolysis of several other benzonitriles gave similar results. Phenanthridine and biphenyl derivatives were obtained as the major products. A mechanism for this novel cycloaromatization reaction of enediynes is proposed

Palladium(II)-Catalyzed <i>Ortho</i> Arylation of 2-Phenoxypyridines with Potassium Aryltrifluoroborates via C−H Functionalization

An efficient synthesis of ortho-arylated 2-phenoxypyridines catalyzed by palladium acetate is described. Treatment of 2-phenoxypyridines with two and a half equivalents of potassium aryltrifluoroborate and 10 mol % of Pd(OAc)2 in the presence of two equivalents of Ag2CO3, one equivalent of p-benzoquinone (BQ), and four equivalents of DMSO with (or without) H2O at 130−140 °C for 48 h in dried CH2Cl2 gave the ortho-arylated 2-phenoxypyridines in modest to excellent yields. p-Benzoquinone is found to be an important ligand and co-oxidant for the transmetalation reductive elimination step in the catalytic reaction. The investigation of kinetic isotope effect (kH/kD) is determined to be 5.25, which indicates that C−H bond cleavage occurs in the rate-determining step. One of the arylated compounds, 2-(4′-nitrobiphenyl-2-yloxy)pyridine, was treated with methyl trifluoromethanesulfonate and subsequently sodium methoxide to give the 2-(4-nitrophenyl)phenol in 79% yield, demonstrating that pyridine is a removable directing group

Palladium-Catalyzed Arylation and Alkylation of 3,5-Diphenylisoxazole with Boronic Acids via C−H Activation

A method for stoichiometric C−H activation of 3,5-diphenylisoxazole (1) using Pd(OAc)2 as a reagent in acetic acid leading to the isoxazole palladacycle I was described. Ortho aryl- and alkyl-substituted 3,5-diphenylisoxazoles 3a−f and 5a−i were synthesized by the reaction of I with various boronic acids 2a−f and 4a−i, respectively. p-Benzoquinone was found to be the best oxidant and 1,4-dioxane the best solvent for the transmetalation−reductive-elimination step of I with boronic acids

Palladium-Catalyzed Annulation of 2-(1-Alkynyl)biphenyls with Aryl Iodides to Disubstituted Methylidenefluorenes.

Palladium-Catalyzed Annulation of 2-(1-Alkynyl)biphenyls with Aryl Iodides to Disubstituted Methylidenefluorenes

Iodine-Mediated Cascade Cyclization of Enediynes to Iodinated Benzo[<i>a</i>]carbazoles

Treatment of N,N-dimethyl 2-[2-(2-ethynylphenyl)­ethynyl]­anilines (1) with 1.2 equiv of iodine in CH2Cl2 gave benzo­[a]­carbazoles (2) in good yields. Mechanistic studies showed this reaction must go through the haloindole (3) followed by iodonium ion catalyzed atom-transfer cyclization reaction to give the benzo­[a]­carbazoles