Alkylated Stereogenic Centers: The Lei/Kong Synthesis of Esermethole
Masaharu Sugiura of Sojo University used a BINAP-derived phosphine oxide to mediate the selective reduction of 1 to 2 (J. Org. Chem. 2019, 84, 11458. ). Jaesook Yoon of Sungkyunkwan University reduced 3 to 4 (Org. Lett. 2019, 21, 8779. ).
Syuzanna R. Harutyunyan of the University of Groningen also found that a BINAP-derived ligand worked well for the preparation of 6 by enantioselective conjugate addition to the free acid 5 (Nature Commun. 2019, 10, 3402. ). Manfred Braun of the Heinrich-Heine University Düsseldorf achieved high ee in the allylation of 7 to give 8 (Eur. J. Org. Chem. 2019, 4604. ). Sanzhong Luo of Tsinghua University assembled 11 by reacting 10 with 9 (Org. Lett. 2019, 21, 7258. ). Zhenyang Lin of the Hong Kong University of Science and Technology and Guosheng Liu of the Shanghai Institute of Organic Chemistry used 13 to effect net oxidative cyanation of 12 to 14 (Nature 2019, 574, 516. ). Xin-Yuan Liu of the Southern University of Science and Technology coupled the racemic bromide 15 with propyne, leading to the alkyne 16 (Nature Chem. 2019, 11, 1158. ). Professor Liu also reported a related procedure, the preparation of 18 by the coupling of 17 with phenylacetylene (Nature Commun. 2019, 10, 5689. ).
Jieping Zhu of the Ecole Polytechnique Fédérale de Lausanne used a phosphoramide to mediate the pinacol rearrangement of 19 to 20 (J. Am. Chem. Soc. 2019, 141, 11372. ). Jianwei Sun, also of the Hong Kong University of Science and Technology, reported a parallel investigation (J. Am. Chem. Soc. 2019, 141, 13783. ). Yu Lan of Chongqing University and Da-Gang Yu of Sichuan University prepared 22 by the reductive hydroxymethylation of 21 (J. Am. Chem. Soc. 2019, 141, 18825. ). Zheng Wang and Kuiling Ding, also of the Shanghai Institute of Organic Chemistry, devised a related protocol for the conversion of the allene 23 to 24 (Chem. Eur. J. 2019, 25, 13874. ). Junliang Zhang of Fudan University acylated the allene 25 with 26, leading to 27 (ACS Catal. 2019, 9, 6890. ).
The alkaloid esermethole (31) was isolated from the African calabar bean Physostigma venenosum. En route to 31, Aiwen Lei and Wangqing Kong of Wuhan University assembled 30 by cyclizing 28 in the presence of 29 (Org. Chem. Front. 2019, 6, 3305. ).