Arrays of Stereogenic Centers: The Knochel Synthesis of Siphonarienal

Shenci Lu and Yu Zhao of the National University of Singapore assembled 3 by adding 1 to 2 (Angew. Chem. Int. Ed. 2018, 57, 1645. DOI: 10.1002/anie.201709823). Lei Shi and Yong-Gui Zhou of the Dalian Institute of Chemical Physics hydrogenated 4 to give 5 (Angew. Chem. Int. Ed. 2018, 57, 5853. DOI: 10.1002/anie.201801485). Steven J. Malcolmson of Duke University devised the reductive addition of 6 to 7, leading to 8 (J. Am. Chem. Soc. 2018, 140, 598, DOI: 10.1021/jacs.7b12213; 7083, DOI: 10.1021/jacs.8b04750). Sebastian Baś of Jagiellonian University prepared 11 by adding 9 to 10 (Org. Biomol. Chem. 2018, 16, 1118. DOI: 10.1039/C7OB02797D).

Takumi Watanabe, Naoya Kumagai and Masakatsu Shibasaki of the Institute of Microbial Chemistry took advantage of the soft ionization of thiocarbonyl compounds, adding 13 to 12 to give 14 (Chem. Eur. J. 2018, 24, 2598, DOI: 10.1002/chem.201800020; J. Org. Chem. 2018, 83, 5851, DOI: 10.1021/acs.joc.8b00743). Łukasz Albrecht of the Lodz University of Technology prepared 17 by adding 16 to 15 (Org. Biomol. Chem. 2018, 16, 376. DOI: 10.1039/C7OB02894F). Jimin Kim of Chonnam National University and Chan-Mo Yu of Sungkyunkwan University combined 18 with 19 to generate in situ a reagent that they then added to 20, leading to the alkyne 21 (Org. Lett. 2018, 20, 1521. DOI: 10.1021/acs.orglett.8b00219). Chun-Jiang Wang of Wuhan University used a dual catalyst to prepare 24 by coupling 22 with 23 (J. Am. Chem. Soc. 2018, 140, 1508. DOI: 10.1021/jacs.7b12174). Wanbin Zhang of Shanghai Jiao Tong University described related results (J. Am. Chem. Soc. 2018, 140, 2080. DOI: 10.1021/jacs.8b00187).

Fabien Gagosz, now at the University of Ottawa, and Shunsuke Chiba of Nanyang Technological University achieved high diastereoselectivity in the reduction of 25 to 26 (Angew. Chem. Int. Ed. 2018, 57, 6181. DOI: 10.1002/anie.201801953). Song Ye of the Institute of Chemistry, Chinese Academy of Sciences, assembled 29 by coupling 27 with 28 (Chem. Eur. J. 2018, 24, 8302. DOI: 10.1002/chem.201801539). Fraser F. Fleming of Drexel University alkylated the nitrile 30 with 31 to give 32 in high de (J. Org. Chem. 2018, 83, 2753. DOI: 10.1021/acs.joc.7b03205). Subhas Chandra Pan of the Indian Institute of Technology Guwahati combined 33 with 34 to give 35 (Synlett 2018, 29, 576. DOI: 10.1055/s-0036-1591736).

Siphonarienal (39), a pentapropionate derivative, was isolated from the marine pulmonate mollusk Siphonaria grisea. In the course of a synthesis of 39, Paul Knochel of Ludwig-Maximilians-Universität München developed a protocol for the transmetalation of 36 and subsequent addition to 37 to give 38, with retention of absolute configuration. It is particularly remarkable that the iodide 36 could be prepared from the corresponding alcohol without racemization (Angew. Chem. Int. Ed. 2018, 57, 5516. DOI: 10.1002/anie.201800792).