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Monday, September 10, 2018
Douglass F. Taber
University of Delaware

Alkene Functionalization: The Weinreb Synthesis of Alstoscholarisine C

Gerald B. Hammond of the University of Louisville and Bo Xu of Donghua University developed a reagent combination that converted the alkene 1 to the bromide 2 (Chem. Eur. J. 2017, 23, 12739. ). Daniel S. Lambrecht and Peng Liu of the University of Pittsburgh and Stephen L. Buchwald of MIT estabished conditions for the conversion of the alkene 3 to the amine 4 (J. Am. Chem. Soc. 2017, 139, 16548. ). Yoshiharu Iwabuchi of Tohoku University achieved high regioselectivity in the oxidation of the alkene 5 to the enone 6 (Chem. Eur. J. 2017, 23, 10276. ). Hongli Bao of the Fujian Institute of Research on the Structure of Matter observed complementary regioselectivity in the oxidation of 7 to 8 (Tetrahedron Lett. 2017, 58, 4125. ).

Kai Sun and Xin Wang of Anyang Normal University oxidized the alkene 9 to the sulfide 10 (Org. Biomol. Chem. 2017, 15, 5258. ). Teng-fei Niu of Jiangnan University developed the light-promoted oxidation of 12 to the keto sulfone 13 (Tetrahedron Lett. 2017, 58, 3667. ).

Bill Morandi of the Max-Planck-Institut für Kohlenforschung used the acid chloride 15 to add the equivalent of CO and HCl to the alkene 14, leading to 16 (Nature Chem. 2017, 9, 1105. ). Pinhong Chen and Guosheng Liu of the Shanghai Institute of Organic Chemistry used 17 to oxidize the alkene 14 to the β-azido ester 18 (J. Org. Chem. 2017, 82, 11682. ).

Lucile Anthore-Dalion, now at the CEA Saclay, and Samir Z. Zard of the Ecole Polytechnique showed that the initial product from the addition of 20 to the alkene 19 could readily be desulfurized. Favorskii rearrangement of the α,α-dichloroketone so prepared led to the Z-unsaturated ester 21 (Org Lett. 2017, 19, 5545. ). Vy M. Dong of the University of California, Irvine added the nitrile 22 to the alkene 1 under oxidative conditions, leading to the branched nitrile 23 (Angew. Chem. Int. Ed. 2017, 56, 11589. ). Michael C. Willis of the University of Oxford showed that the aldehyde 24 could be added to the alkene 14 to give the ketone 25 (J. Am. Chem. Soc. 2017, 139, 10142. ). Atsuo Nakazaki of Nagoya University demonstrated that the Heck addition of 27 to 26 delivered 28 with high regio- and diastereocontrol (J. Org. Chem. 2017, 82, 9097. ).

Pendant allyl groups, as illustrated by 29, can often be carried through several steps of a synthesis, then reacted selectively. In the course of a synthesis of alstoscholarisine C (32), Steven M. Weinreb of Pennsylvania State University observed that the terminal alkene of 29 engaged in an intramolecular ene reaction with 30 under mild conditions to give 31 (Angew. Chem. Int. Ed. 2017, 56, 16674. ).

D. F. Taber, Org. Chem. Highlights 2018, September 10.