Polycyclic Aromatic Hydrocarbons Copper-Catalyzed Synthesis of Amino-Substituted Polycyclic Aromatic Hydrocarbons by the Sequential Reaction between Aryl Alkynyl Carboxylic Acids and Amines Jinseop Choi, [a] Kyungho Park, [a] Jeongah Lim, [a] Hyun Min Jung,* [b] and Sunwoo Lee* [a] Abstract: Amino-substituted polycyclic aromatic hydrocar- bons were obtained by the reaction between aryl alkynyl carboxylic acids and amines in the presence of a copper cat- alyst. The hydrocarbons were obtained in good yield with- out the need to isolate the 1,4-diaryl-1,3-butadiyne inter- mediate. The best result was obtained using a combination of CuCl and Cu(OTf) 2 , and the reactions of cyclic and acyclic secondary amines afforded the desired products. Introduction One-pot sequential synthesis is one of the most powerful tools in organic synthesis because of advantages such as time and process economy. [1] Since our first report of the palladium-cata- lyzed decarboxylative coupling of aryl halides and propiolic acid, a number of decarboxylative coupling reactions with pro- piolic acid derivatives have been reported. [2] Aryl alkynyl car- boxylic acids, which are one of the derivatives of propiolic acid, have been commonly used as starting materials in decar- boxylative coupling reactions. They have been used for the construction of several useful organic building blocks, such as diaryl alkyne, [3] 1,4-diaryldiyne, [4] alkynyl ketone, [5] alkynyl amide, [6] alkynyl phosphine, [7] and allyl alkyne. [8] Among these examples, the synthesis of diaryl alkynes from aryl halides has been much studied by our group as well as other groups. In addition, diaryl alkynes have also been used in sequential cou- pling and cyclization to afford heterocyclic compounds, such as imidazopyridine, arylindole, isocoumarin, phthalide, isoindo- linone, and isoquinolinone. [9] The Hua group has reported the copper-catalyzed synthesis of amino-substituted naphthalene derivatives by the reaction between diaryl buta-1,3-diynes and cyclic amines (Scheme 1 a). [10] Although they were the first to develop the synthetic approach to naphthalene derivatives from diyne, this approach has several drawbacks, as the diyne needs to be pre- pared, an excess of amine (30 equivalents) as a solvent is re- quired, and the preparation is limited to cyclic amines. In our continuing interest toward the development of decarboxyla- tive coupling reactions, we discovered that an amino-substitut- ed naphthalene was obtained by the reaction between phenyl propiolic acid and an amine in the presence of a copper cata- lyst. This result prompted us to develop the one-pot synthesis of polycyclic aromatic hydrocarbons from aryl alkynyl carboxyl- ic acids without the use of excess amine. In addition, amino- substituted polycyclic aromatic hydrocarbons are important building blocks in medicinal and material chemistry. [11] Here, we report the copper-catalyzed one-pot synthesis of amino- substituted polycyclic aromatic hydrocarbons by the reaction between alkynyl carboxylic acids and amines (Scheme 1 b). Results and Discussion To optimize the reaction conditions, the reaction between phenyl propiolic acid and morpholine was chosen as the model reaction, and various solvents and copper catalysts were investigated. Instead of using an excess of morpholine, Scheme 1. Synthesis of amino-substituted naphthalenes. [a] J. Choi, Dr. K. Park, J. Lim, Prof. S. Lee Department of Chemistry Chonnam National University Gwangju 500-757 (Republic of Korea) Fax: (+ 82) 62-530-3389 E-mail : sunwoo@chonnam.ac.kr [b] Prof. H. M. Jung Department of Applied Chemistry Kumoh National Institute of Technology Gumi, 730-701 (Republic of Korea) E-mail : hmjung@kumoh.ac.kr Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/ajoc.201500227. Asian J. Org. Chem. 2015, 4, 969 – 974 # 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 969 Full Paper DOI: 10.1002/ajoc.201500227