Functional Group Interconversion: The Fuwa Synthesis of Enigmazole A
N. Gabriel Lemcoff of the Ben-Gurion University of the Negev and Ofer Reany of the Open University of Israel used a thiourea to catalyze the N-bromosuccinimide conversion of the alcohol 1 to the bromide 2 (J. Org. Chem. 2020, 85, 12901. ). Léon Ghosez of the University of Bordeaux and UCLouvain showed that the conversion of the alcohol 3 to the chloride 5 with the chloro enamine 4 proceeded with clean inversion of absolute configuration (Tetrahedron 2020, 76, 131441. ).
Alessandro Palmieri of the University of Camerino observed that the deconjugation of the enone 6 to the nitroalkene 7 proceeded with high geometric selectivity (Adv. Synth. Catal. 2020, 362, 4680. ). Shou-Fei Zhu of Nankai University demonstrated that with the proper choice of iron catalyst, phenyl silane 9 could be added to the alkyne 8 to give either regioisomer of the alkenyl silane 10 (J. Am. Chem. Soc. 2020, 142, 16894. ). Song Lin of Cornell University prepared the allyl silane 12 by the reductive coupling of the phenyl ether 11 with trimethylsilyl chloride (J. Am. Chem. Soc. 2020, 142, 21272. ). Bitragunta Sivakumar and Subramaniyan Mannathan of SRM University-AP used benzonitrile to mediate the N-alkylation of aniline with the alcohol 13 (Adv. Synth. Catal. 2020, 362, 4409. ). Chunyan Zhang and Guoyin Zhang of the Qingdao University of Science and Technology and Mao-Lin Hu of Wenzhou University described a parallel investigation (Chem. Commun. 2020, 56, 10489. ).
Koji Kubota and Hajime Ito of Hokkaido University developed a general route to the trialkylsilylborane 16, and added it in a conjugate sense to cyclohexenone 15, leading to the ketone 17 (J. Am. Chem. Soc. 2020, 142, 14125. ). Zhenyang Lin of Hunan University and Wanxiang Zhao of the Hong Kong University of Science and Technology used a Rh catalyst to add B2pin2 (19) to the ketone 18, leading to the alkenyl boronate 20 (J. Am. Chem. Soc. 2020, 142, 18118. ). Jun Huang and Zhen Yang of Peking University Shenzhen Graduate School used an iridium photocatalyst to mediate the isomerization of the allylic alcohol 21 to the aldehyde 22 (Angew. Chem. Int. Ed. 2020, 59, 11660. ). Xinying Zhang and Xuesen Fan of Henan Normal University assembled the amide 25 by coupling benzoic acid (24) with the alkenyl azide 23 (J. Org. Chem. 2020, 85, 13710. ).
Chien-Fu Liang of National Chung Hsing University prepared the N-sulfonylthioimidate 27 from the terminal alkyne 26 (Org. Biomol. Chem. 2020, 18, 8881. ). Qiuping Ding of Jiangxi Normal University and Yong Luo of Sun Yat-Sen University established oxidative conditions for the conversion of the N-sulfonyl amide 28 to the aryl ester 29 (Tetrahedron Lett. 2020, 61, 152444. ).
Enigmazole A (32), isolated from a marine sponge Cinachyrella enigmatica of Papua New Guinea, showed activity in the NCI 60-cell panel. In the course of a synthesis of 32, Haruhiko Fuwa of Chuo University used a gold catalyst to effect the rearrangement of the propargyl ester 30 to the enone 31 (Chem. Asian J. 2020, 15, 3494. ).