Carbon-Carbon Bond Formation: The Burtoloso Synthesis of Brussonol
Kevin Lam of the University of Greenwich assembled 3 by coupling 1 with 2 under Kolbe conditions (Angew. Chem. Int. Ed. 2019, 58, 16115. DOI: 10.1002/anie.201909922). Kimihiro Komeyama of Hiroshima University coupled 4 selectively with 5, leading to 6 (ACS Catal. 2019, 9, 9285. DOI: 10.1021/acscatal.9b03352). Sophie A. L. Rousseaux of the University of Toronto showed that 7 could be combined with the homoenolate from 8 to give 9 (Org. Lett. 2019, 21, 8805. DOI: 10.1021/acs.orglett.9b03435). Kai Zhao of Nanjing Tech University and Teck-Peng Loh of Nanyang Technological University found that such homoenolates could be induced to undergo conjugate addition (not illustrated) (Org. Lett. 2019, 21, 5101. DOI: 10.1021/acs.orglett.9b01703). Professor Rousseaux also established conditions for cyano transfer from 11 to an alkyl lithium 10, generating a new nitrile anion that was alkylated with 12 to give 13 (Angew. Chem. Int. Ed. 2019, 58, 10300. DOI: 10.1002/anie.201903215).
Michael J. Krische of the University of Texas and Ronaldo A. Pilli of the University of Campinas optimized the preparation of 16 by the delicate coupling of 14 with 15 (J. Am. Chem. Soc. 2019, 141, 13778. DOI: 10.1021/jacs.9b07512). Gojko Lalic of the University of Washington assembled the Z alkene 19 by coupling the alkyne 17 with 18 (J. Am. Chem. Soc. 2019, 141, 17086. DOI: 10.1021/jacs.9b09336). Peng Cao of Sichuan Normal University used the diene 22 as a linchpin, combining it with 20 and 21 to give 23 (ACS Catal. 2019, 9, 11788. DOI: 10.1021/acscatal.9b04183). Jian Zhang and Guofu Zhong of Hangzhou Normal University prepared the trisubstituted alkene 26 via the oxidative coupling of 24 with 25 (Nature Commun. 2019, 10, 5109. DOI: 10.1038/s41467-019-13098-1).
Timothy NoŽl of the Eindhoven University of Technology devised flow conditions for the generation of the Grignard reagent from 27 and the subsequent coupling with 28 to give the alkyne 29 (Chem. Eur. J. 2019, 25, 14532. DOI: 10.1002/chem.201904480). Ming Chen of Auburn University opened the cyclopropane 31 with 30, leading to 32 (Chem. Sci. 2019, 10, 10601. DOI: 10.1039/C9SC04122B).
Hui Qian of Fudan University and Yin-Long Guo and Shengming Ma of the Shanghai Institute of Organic Chemistry selectively converted one of the enantiomers of 33 to the allene 34 (Nature Catal. 2019, 2, 997. DOI: 10.1038/s41929-019-0346-z). Hirokazu Tsukamoto of the Yokohama University of Pharmacy prepared the allene 37 by adding the malonate 36 to 35 (Org. Lett. 2019, 21, 6811. DOI: 10.1021/acs.orglett.9b02439). Stephen L. Buchwald of MIT described a related allene preparation using nucleophilic hydride (not illustrated) (J. Am. Chem. Soc. 2019, 141, 13788. DOI: 10.1021/jacs.9b07582).
Brussonol (41), isolated from the Canary Island perennial shrub Salvia broussonetii, displayed cytotoxicity and insect antifeedant activity. En route to 41, Antonio C. B. Burtoloso of the Universidade de Sao Paulo used the Weix protocol to assemble 40 by selectively coupling 39 with 38 (Org. Lett. 2019, 21, 6079. DOI: 10.1021/acs.orglett.9b02221).