Carbon-Carbon Bond Construction: The Taylor/Fairlamb Synthesis of Phacelocarpus 2-Pyrone A
Gregory C. Fu and Jonas C. Peters of Caltech reported (J. Am. Chem. Soc. 2015, 137, 13902. DOI: 10.1021/jacs.5b08452) the preparation of nitrile 2 by the UV (254 nm)-assisted displacement of the hindered chloride 1. Toru Amaya and Toshikazu Hirao of Osaka University achieved (J. Am. Chem. Soc. 2015, 137, 10072. DOI: 10.1021/jacs.5b05058) the cross-coupling of 3 with 4 to make 5. Maurizio Fagnoni of the University of Pavia and Ilhyong Ryu of Osaka Prefecture University added (J. Org. Chem. 2015, 80, 9365. DOI: 10.1021/acs.joc.5b01850) the acyl radical derived photolytically from 7 to the enone 6, to give 8. David W. C. MacMillan of Princeton University used (Science 2015, 349, 1532. DOI: 10.1126/science.aac8555) an Ir photocatalyst and visible light to mediate the construction of 11 by the addition of 9 to 10.
β-Keto sulfones such as 12 are versatiles intermediates for organic synthesis. Ganesh Pandey of SGPGIMS Campus Lucknow further extended their utility by demonstrating (Org. Lett. 2015, 17, 4890. DOI: 10.1021/acs.orglett.5b02455) the conversion of 12 to 13. Masaharu Sugiura of Kumamoto University accomplished (J. Org. Chem. 2015, 80, 8830. DOI: 10.1021/acs.joc.5b01217) the preparation of 16 by the aldol addition of the ketone 14 to the ketone 15. Axel Jacobi von Wangelin of the University of Regensburg used (Angew. Chem. Int. Ed. 2015, 54, 10545. DOI: 10.1002/anie.201504524) an Fe catalyst to mediate the assembly of 19 by the coupling of 18 with the enol acetate 17. Tetsuaki Fujihara and Yasushi Tsuji of Kyoto University demonstrated (Chem. Commun. 2015, 51, 13020. DOI: 10.1039/C5CC03932K) the reductive condensation of the allene 20 with CO2 to prepare the alcohol 21. Michael J. Krische of the University of Texas reported (Angew. Chem. Int. Ed. 2015, 54, 8525. DOI: 10.1002/anie.201503250) a related preparation of amines (not illustrated).
Jin Kun Cha of Wayne State University described (Org. Lett. 2015, 17, 3854. DOI: 10.1021/acs.orglett.5b01789) the coupling of 23 with the Kulinkovich product 22 to give the ketone 24. Xin-Hua Duan of Xi'an Jiaotong University reported (Org. Lett. 2015, 17, 4798. DOI: 10.1021/acs.orglett.5b02353) parallel results with cyclopropanols, cyclobutanols and cyclopentanols (not illustrated). Jerome Waser of the École Polytechnique Fédéral de Lausanne (Angew. Chem. Int. Ed. 2015, 54, 11200. DOI: 10.1002/anie.201505111) and Liang-Qiu Lu and Wen-Jing Xiao of Central China Normal University (Angew. Chem. Int. Ed. 2015, 54, 11196. DOI: 10.1002/anie.201504559) observed the decarboxylative coupling of a carboxylic acid 25 with 26 to give the alkyne 27.
Yun-He Xu and Teck-Peng Loh of the University of Science and Technology of China achieved (J. Am. Chem. Soc. 2015, 137, 14830. DOI: 10.1021/jacs.5b08279) high ee in the preparation of the allene 29 by the silylation of 28. Xiaohua Liu of Sichuan University coupled (Angew. Chem. Int. Ed. 2015, 54, 9512. DOI: 10.1002/anie.201501918) the diazo ester 31 with the alkyne 30 to give the allene 32, also in high ee.
Richard J. K. Taylor and Ian J. S. Fairlamb of the University of York assembled (Chem. Eur. J. 2015, 21, 18905. DOI: 10.1002/chem.201504089) phacelocarpus 2-pyrone A (36) by the Wittig addition of 34 to 33, followed by the intramolecular Pd-mediated coupling of the product 35. In the course of this work, the authors corrected the assignment of the geometry of the enol ether of the natural product.