Heteroaromatics: The Carter Synthesis of Halenaquinone

José F. Quílez del Moral and Alejandro F. Barrero of the University of Granada oxidized the enone 1 to the furan 2 (J. Org. Chem. 2019, 84, 6886. DOI: 10.1021/acs.joc.9b00704). Debaraj Mukherjee of the Indian Institute of Integrative Medicine rearranged the glucose derivative 3 to the furan 4 (Org. Lett. 2019, 21, 3034. DOI: 10.1021/acs.orglett.9b00680). Ian A. Tonks of the University of Minnesota devised a modular Ti-catalyzed assembly of the pyrrole 7, combining the alkyne 5 with the alkyne 6 (ACS Catal. 2019, 9, 216. DOI: 10.1021/acscatal.8b04669). Patrick G. Harran of UCLA effected the oxidative rearrangement of the pyridine 8 to the macrocyclic pyrrole 9 (J. Am. Chem. Soc. 2019, 141, 2274. DOI: 10.1021/jacs.9b00396).

Hiroyuki Konno of Yamagata University established a modular assembly of the ketal 10, that was then carried on to the pyridine 11 (Org. Biomol. Chem. 2019, 17, 2896. DOI: 10.1039/C8OB02723D). Chandi C. Malakar of the National Institute of Technology Manipur achieved high selectivity in the preparation of 14 by the condensation of 12 with 13 (J. Org. Chem. 2019, 84, 5005. DOI: 10.1021/acs.joc.8b02971). Yun Li of Lanzhou University combined the enone 15 with the propargyl amine 16 to give 17 (Angew. Chem. Int. Ed. 2019, 58, 1148. DOI: 10.1002/anie.201811812). E. Blake Watkins of Union University described a parallel investigation (Chem. Commun. 2019, 55, 3270. DOI: 10.1039/C9CC01097A).

Andrew Sutherland of the University of Glasgow prepared 20 by the hetero Diels-Alder combination of 18 with 19 followed by exposure to hydroxylamine (J. Org. Chem. 2019, 84, 2879. DOI: 10.1021/acs.joc.9b00036).

Sobi Asako and Kazuhiko Takai of Okayama University used stoichiometric 22 and Mo(CO)₆ to effect the oxidative cyclization of 21 to the indole 23 (J. Am. Chem. Soc. 2019, 141, 9832. DOI: 10.1021/jacs.9b05428). Min Wang of Hangzhou Normal University incorporated a carbon atom from DMSO in converting 24 to 25 (Org. Lett. 2019, 21, 3658. DOI: 10.1021/acs.orglett.9b01093). Wen-Bo Liu of Wuhan University cyclized 26 to 27 (J. Org. Chem. 2019, 84, 7995, DOI: 10.1021/acs.joc.9b00866; Org. Lett. 2019, 21, 1082. DOI: 10.1021/acs.orglett.8b04128). Fuhong Xiao, Yanjun Xie and Guo-Jun Deng of Xiangtan University assembled 30 by adding 28 to 29 (J. Org. Chem. 2019, 84, 568, DOI: 10.1021/acs.joc.8b02410; Chem. Commun. 2019, 55, 4079. DOI: 10.1039/C9CC00943D).

Halenaquinone (33), isolated from the marine sponge Xestospongia exigua, showed antibiotic activity against both Staphylococcus and Bacillus subtilis. In the course of a synthesis of 33, Rich G. Carter of Oregon State University oxidized 31 to the furan 32 (Angew. Chem. Int. Ed. 2018, 57, 9117. DOI: 10.1002/anie.201805370).