Heteroaromatics: The Zhou/Li Synthesis of Goniomitine
Xin-Yan Wu of the East China University of Science and Technology and Jun Yang of the Shanghai Institute of Organic Chemistry added (Tetrahedron Lett. 2014, 55, 4071. DOI: 10.1016/j.tetlet.2014.05.106) the Grignard reagent 1 to propargyl alcohol 2 to give an intermediate that could be borylated, then coupled under Pd catalysis with an anhydride, leading to the furan 3. Fuwei Li of the Lanzhou Institute of Chemical Physics constructed (Org. Lett. 2014, 16, 5992. DOI: 10.1021/ol503009f) the furan 6 by oxidizing the keto ester 4 in the presence of the enamide 5.
Yuanhong Liu of the Shanghai Institute of Organic Chemistry prepared (Angew. Chem. Int. Ed. 2014, 53, 11596. DOI: 10.1002/anie.201407221) the pyrrole 9 by reducing the azadiene 7 with the Negishi reagent, then adding the nitrile 8. Yefeng Tang of Tsinghua University found (Tetrahedron Lett. 2014, 55, 6455. DOI: 10.1016/j.tetlet.2014.09.134) that the Rh carbene derived from 11 could be added to an enol silyl ether 10 to give the pyrrole 12. Pazhamalai Anbarasan of the Indian Institute of Technology Madras reported (J. Org. Chem. 2014, 79, 8428. DOI: 10.1021/jo501043h) related results.
Zheng Huang of the Shanghai Institute of Organic Chemistry established (Angew. Chem. Int. Ed. 2014, 53, 1390. DOI: 10.1002/anie.201306559) a connection between substituted piperidines and pyridines by dehydrogenating 13 to 15. Joseph P. A. Harrity of the University of Sheffield conceived (Chem. Eur. J. 2014, 20, 12889. DOI: 10.1002/chem.201403916) the cascade assembly of the pyridine 18 by cycloaddition of 16 with 17 followed by Pd-catalyzed coupling. Teck-Peng Loh of Nanyang Technological University converted (Org. Lett. 2014, 16, 3432. DOI: 10.1021/ol501010k) the keto ester 19 into the azirine, then eliminated it to form an azatriene that cyclized to the pyridine 20. En route to a cholesteryl ester transfer protein inhibitor, Zhengxu S. Han of Boehringer Ingelheim combined (Org. Lett. 2014, 16, 4142. DOI: 10.1021/ol501833g) 21 with 22 to give an intermediate that could be oxidized to 23.
Magnus Rueping of RWTH Aachen used (Angew. Chem. Int. Ed. 2014, 53, 13264. DOI: 10.1002/anie.201405478) an Ir photoredox catalyst in conjunction with a Pd catalyst to cyclize the enamine 24 to the indole 25. Yingming Yao and Yingsheng Zhao of Soochow University effected (Angew. Chem. Int. Ed. 2014, 53, 9884. DOI: 10.1002/anie.201404854) oxidative cyclization of 26 to indoline 27. Cheon-Gyu Cho of Hanyang University showed (Org. Lett. 2014, 16, 4492. DOI: 10.1021/ol502031q) that ZnCl2 cyclized the coupling product between 28 and 29 with high fidelity to give 30. Acid-catalyzed cyclization led predominantly to the other regioisomer. Yanxing Jia of Peking University cyclized (Chem. Commun. 2014, 50, 7367. DOI: 10.1039/C4CC02947J) 31 to 32. Xianxiu Xu and Qun Liu of Northeast Normal University (Chem. Commun. 2014, 50, 7306. DOI: 10.1039/C4CC02398F) and Bing Zhou and Yuanchao Li of the Shanghai Institute of Materia Medica (Org. Lett. 2014, 16, 3900. DOI: 10.1021/ol501599j) reported similar results.
Professors Zhou and Li used (Chem. Eur. J. 2014, 20, 12768. DOI: 10.1002/chem.201403973) a Rh catalyst followed by acid to cyclize the hydrazide 33. The product 34 was readily carried on to the alkaloid Goniomitine 35.