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Monday, February 26, 2018
Douglass F. Taber
University of Delaware

Arrays of Stereogenic Centers: The Ellman Synthesis of (+)-Pancratistatin

Ayyanar Silva of Madurai Kamaraj University developed (Org. Biomol. Chem. 2017, 15, 2551. DOI: 10.1039/C7OB00031F) the oxidative combination of an aldehyde 1 with styrene 2 to give the epoxide 3. Kilian Muņiz of ICIQ effected (J. Am. Chem. Soc. 2017, 139, 4354. DOI: 10.1021/jacs.7b01443) the oxidative bis amination of 4 with 5, leading to 6. Joseph J. Topczewski of the University of Minnesota took advantage (J. Am. Chem. Soc. 2017, 139, 7737. DOI: 10.1021/jacs.7b04203) of the thermal equilibration of allylic azides, converting 7 to the diol 8. Yutaka Ukaji of Kanazawa University assembled (J. Org. Chem. 2017, 82, 1969. DOI: 10.1021/acs.joc.6b02816) 11 by adding 9 to the alcohol 10.

Gaoxi Jiang of the Lanzhou Institute of Chemical Physics developed (Angew. Chem. Int. Ed. 2017, 56, 1077. DOI: 10.1002/anie.201610473) the allylic coupling of 12 with the allene 13, leading to 14. David B. Collum of Cornell University and Armen Zakarian of the University of California, Santa Barbara added (J. Am. Chem. Soc. 2017, 139, 527. DOI: 10.1021/jacs.6b11673) 16 in a conjugate sense to 15 to give 17. Bin Fu of China Agricultural University prepared (Eur. J. Org. Chem. 2017, 657. DOI: 10.1002/ejoc.201601540) 20 by the Ni-catalyzed combination of 18 with 19. Zhi-Yong Han of the University of Science and Technology of China activated (Chem. Commun. 2017, 53, 1985. DOI: 10.1039/C6CC09654A) 22 under Ir catalysis, adding the intermediate organometallic to the imine 21 to give 23.

Pedro Merino of the Universidad de Zaragoza and Jose L. Vicario of the University of the Basque Country combined (Chem. Sci. 2017, 8, 2904. DOI: 10.1039/C7SC00009J) 24 with 25 to give the aldehyde 26. Feliu Maseras and Paolo Melchiorre of ICIQ generated (Angew. Chem. Int. Ed. 2017, 56, 3304. DOI: 10.1002/anie.201612159) the photoenol from 27, then added it to the in situ generated iminium salt derived from 28, leading to the aldehyde 29. Zheng Wang and Kuiling Ding of the Shanghai Institute of Organic Chemistry achieved (Angew. Chem. Int. Ed. 2017, 56, 5050. DOI: 10.1002/anie.201701455) high enantioselectivity in the preparation of 32 by the allylic coupling of 31 with 30. Wen-Hua Zheng of Nanjing University oxidized (Chem. Commun. 2017, 53, 3737. DOI: 10.1039/C7CC00457E) the prochiral bis acetal 33 to the diester 34 in high ee.

Pancratistatin (38), isolated from the bulbs of the Hawaiian spider lily Hymenocallis littoralis, shows significant anticancer activity. Jonathan A. Ellman of Yale University secured (Org. Lett. 2017, 19, 2985. DOI: 10.1021/acs.orglett.7b01220) four of the six contiguous stereogenic centers of 38 by ortho metalation of 35, followed by diastereoselective conjugate addition of the intermediate organometallic to 36 to give 37.

D. F. Taber, Org. Chem. Highlights 2018, February 26.