Alkene Functionalization: The Evans Synthesis of Thapsigargin
Francisco Foubelo and Miguel Yus of the Universidad de Alicante showed (Eur. J. Org. Chem. 2016, 4067. ) 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. ) 4 by the oxidative silylation of 3. Miguel A. Huertos of the University of Basque Country established (ChemCatChem 2017, 9, 1901. ) conditions for the migratory hydrosilylation of 5 to 6. Aiwen Lei of Wuhan University described (ACS Catal. 2017, 7, 1432. ) 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. ) 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. ) complementary results. Lang Chen and Shuang-Feng Yin of Hunan University effected (Adv. Synth. Catal. 2017, 359, 841. ) the oxidative conversion of 9 to 12.
Troels Skrydstrup of Aarhus University prepared (ACS Catal. 2017, 7, 1392. ) 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. ) 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. ) 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. ) the decarbonylative addition of 18 to 9 to give 19.
Hye-Young Jang of Ajou University developed (Eur. J. Org. Chem. 2017, 1139. ) an effective catalyst for the oxidative bis-carboxylation of the alkene 20 to the succinic acid derivative 21. Building on his previous work ( 2016, January 25), Yannick Landais of the University of Bordeaux assembled (Chem. Eur. J. 2017, 23, 2439, 4651. ) 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. ) the Mukaiyama protocol to effect diastereoselective hydroxylation of 26 to 27.