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Monday, July 9, 2018
Douglass F. Taber
University of Delaware

Enantioselective Synthesis of Alcohols and Amines: The Lindel Synthesis of Hemiasterlin

Lei Shi of the Harbin Institute of Technology achieved high ee in the preparation of 3 by the esterification of 2 with the diazo ester 1 (Adv. Synth. Catal. 2017, 359, 2754. ). Dzmitry G. Kananovich of the Tallinn University of Technology used an organocatalyst to direct the absolute sense of the rearrangement to the keto epoxide 5 of the peroxide derived from the oxidation of 4 (Org. Lett. 2017, 19, 3544. ). Taichi Kano and Keiji Maruoka of Kyoto University used a trityl pyrrolidine prepared from the inexpensive L-hydroxyproline to mediate the oxidation of the aldehyde 6 with benzoyl peroxide 7, leading to 8 (J. Org. Chem. 2017, 82, 12928. ). Fernando Bravo and Miquel A. Pericās of ICIQ also prepared organocatalysts from L-hydroxyproline (Adv. Synth. Catal. 2017, 359, 2414, not illustrated. ).

Justin Du Bois of Stanford University and Matthew S. Sigman of the University of Utah established conditions for the specific hydroxylation of the methine of 9. The reaction proceeded with retention of absolute configuration, to give 10 (J. Am. Chem. Soc. 2017, 139, 9503. ).

Olivier Baudoin of the University of Basel deprotonated 11 in the presence of (-)-sparteine to give an intermediate that could be coupled with 12, leading to 13 in high ee (Org. Lett. 2017, 19, 166. ). Yohei Shimizu and Motomu Kanai of the University of Tokyo assembled the tertiary alcohol 16 by adding the alkyne 15 to the ketone 14 (J. Am. Chem. Soc. 2017, 139, 4647. ).

Thomas C. Coombs of the University of North Carolina Wilmington demonstrated that the aldehyde 6 could be aminated with 17, leading directly to the protected amine 18 (Tetrahedron Lett. 2017, 58, 4623. ). Hui Lv of Wuhan University and Lung Wa Chung and Xumu Zhang of the South University of Science and Technology of China effected enantioselective hydrogenation of 19 to 20 (Chem. Sci. 2017, 8, 6419. ). Elisabetta Brenna of the Politecnico di Milano accomplished enantioselective bioreduction of related substrates (ChemCatChem 2017, 9, 2480, not illustrated. ). Gideon Grogan of the University of York and Nicholas J. Turner of the University of Manchester found a reductive aminase that coupled 22 with 21, leading to 23 (Nature Chem. 2017, 9, 961. ). Hien M. Nguyen of the University of Iowa took advantage of the inherent regioselectivity of Rh π-allyl complexes, combining 24 with 25 to give 26 (Org. Lett. 2017, 19, 4814. ).

Chen-Guo Feng and Guo-Qiang Lin of the Shanghai Institute of Organic Chemistry prepared 29 by adding 28 to 27 (Org. Lett. 2017, 19, 5601. ). Zhan-Jiang Zheng and Li-Wen Xu of Hangzhou Normal University coupled 31 with 30, leading to 32 (Org. Lett. 2017, 19, 4896. ).

Hemiasterlin (36), originally isolated from the South African sponge Hemiasterella minor, shows potent anticancer activity. To prepare the key intermediate 35, Thomas Lindel of the Technical University Braunschweig used an organocatalyst to direct the absolute sense of the amination of 33 with 34 (Chem. Eur. J. 2017, 23, 12714. ).

D. F. Taber, Org. Chem. Highlights 2017, July 9.