Organic Chemistry Portal
Organic Chemistry Highlights

Monday, October 30, 2017
Douglass F. Taber
University of Delaware

Alkene Functionalization: The Evans Synthesis of Thapsigargin

Francisco Foubelo and Miguel Yus of the Universidad de Alicante showed (Eur. J. Org. Chem. 2016, 4067. DOI: 10.1002/ejoc.201600612) that erbium triflate is an efficient catalyst for the conversion of an epoxide 1 to the aldehyde 2. Chun Cai of the Nanjing University of Science and Technology prepared (Chem. Commun. 2016, 52, 10779. DOI: 10.1039/C6CC05509E) silane 4 by the oxidative silylation of 3. Miguel A. Huertos of the University of Basque Country established (ChemCatChem 2017, 9, 1901. DOI: 10.1002/cctc.201700222) conditions for the migratory hydrosilylation of 5 to 6. Aiwen Lei of Wuhan University described (ACS Catal. 2017, 7, 1432. DOI: 10.1021/acscatal.6b03388) the conversion of 7 to the diol 8 as a single diastereomer, although the relative configuration was not reported.

Wei Li of the University of Toledo developed (Org. Lett. 2017, 19, 930. DOI: 10.1021/acs.orglett.7b00079) the regioselective addition of 10 to 9 to make 11. Qiang Zhu of the Guangzhou Institutes of Biomedicine and Health described (Chem. Commun. 2017, 53, 3450. DOI: 10.1039/C7CC00083A) complementary results. Lang Chen and Shuang-Feng Yin of Hunan University effected (Adv. Synth. Catal. 2017, 359, 841. DOI: 10.1002/adsc.201601211) the oxidative conversion of 9 to 12.

Troels Skrydstrup of Aarhus University prepared (ACS Catal. 2017, 7, 1392. DOI: 10.1021/acscatal.6b03571) the carboxylic acid 14 by the diastereoselective hydroboration/carboxylation of the alkene 13. Guosheng Liu of the Shanghai Institute of Organic Chemistry devised (Angew. Chem. Int. Ed. 2016, 55, 13843. DOI: 10.1002/anie.201607248) conditions for the oxidative conversion of 9 to 15.

Zheng-Jun Quan and Xi-Cun Wang of Northwest Normal University assembled (Adv. Synth. Catal. 2016, 358, 3179. DOI: 10.1002/adsc.201600586) the branched alkene 17 by the addition of 16 to 9. Erik J. Alexanian of the University of North Carolina effected (Org. Lett. 2017, 19, 2350. DOI: 10.1021/acs.orglett.7b00882) the decarbonylative addition of 18 to 9 to give 19.

Hye-Young Jang of Ajou University developed (Eur. J. Org. Chem. 2017, 1139. DOI: 10.1002/ejoc.201601546) an effective catalyst for the oxidative bis-carboxylation of the alkene 20 to the succinic acid derivative 21. Building on his previous work (Reactions of Alkenes: The Kutsumura/Saito synthesis of Aplysinoplide B 2016, January 25), Yannick Landais of the University of Bordeaux assembled (Chem. Eur. J. 2017, 23, 2439, 4651. DOI: 10.1002/chem.201605043) 25 by the addition of 23 to the alkene 22 in the presence of the bis sulfone 24.

The highly oxygenated guaianolide thapsigargin (28), isolated from the deadly carrot Thapsia garganica, is a selective subnanomolar inhibitor of intracellular calcium ion transport enzymes. In the course of a concise synthesis of 28, P. Andrew Evans of Queen's University used (J. Am. Chem. Soc. 2017, 139, 6046. DOI: 10.1021/jacs.7b01734) the Mukaiyama protocol to effect diastereoselective hydroxylation of 26 to 27.

D. F. Taber, Org. Chem. Highlights 2017, October 30.