Gold promoted arylative cyclization of alkynoic acids with arenediazonium salts
作者:Ulises A. Carrillo-Arcos、Susana Porcel
DOI:10.1039/c7ob02447a
日期:——
Alkynoicacids derived from salicylic acid and analogues undergo arylative cyclization with arenediazonium salts promoted by gold in the absence of external ligands. The reaction is thermally induced and proceeds even in the absence of light. A difference in regioselectivity has been found compared with that observed in the cycloisomerization process of the same type of compounds.
Palladium-Catalyzed Cyclization of Alkynoic Acids To Form Vinyl Dioxanones Bearing a Quaternary Allylic Carbon
作者:Yohei Ogiwara、Kazuya Sato、Norio Sakai
DOI:10.1021/acs.orglett.7b02572
日期:2017.10.6
A palladium-catalyzed intramolecular reaction of carboxylic acids and alkynes in a novel cyclization manner was developed. This unique cyclization efficiently provided a wide range of complex ring systems—vinyl dioxanones bearing a quaternary allylic carbon. Mechanistic studies suggest an allenyl carboxylate as an intermediate.
A highly regio- and stereoselective synthesis of (Z )-3-arylidene-2,3-dihydro-5H-1,4-benzodioxepin-5-ones and (Z )-3-arylidene-1,2,3,5-tetrahydro-4,1-benzoxazepin-5-ones through palladium–copper catalysis
作者:Gopeswar Chaudhuri、Nitya G. Kundu
DOI:10.1039/a908682j
日期:——
Sodium 2-(prop-2â²-ynyloxy)benzoate 1a reacted with the aryl iodides 2â10 in the presence of bis(triphenylphosphine)palladium(II) chloride, cuprous iodide and triethylamine in CH3CNâDMF to yield the disubstituted alkynes 11â19 in good yields (48â58%). Similarly, sodium 2-[N-benzyl-N-(prop-2â²-ynyl)]aminobenzoate 1b on reaction with aryl iodides under palladiumâcopper catalysis afforded the disubstituted alkynes 20â22. Compounds 11â19 on cyclisation with cuprous iodide in the presence of triethylamine in acetonitrile yielded the 3-arylidene-2,3-dihydro-5H-1,4-benzodioxepin-5-ones 23â31 in 61â83% yields. Similarly, compounds 20â22 on cyclisation gave 3-arylidene-1,2,3,5-tetrahydro-4,1-benzoxazepin-5-ones 32â34.
The unique cyclization of benzamide derivatives that contain an alkyne by a Pd(0)/dialkyl(biaryl)phosphine catalytic system is reported. The reaction efficiently provides a variety of six-membered N-heterocyclic compounds that contain a fully substituted carbon center without the need for a stoichiometric additive. Mechanistic studies suggest that this unprecedented cyclization starts with the cleavage