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Monday, June 17, 2019
Douglass F. Taber
University of Delaware

Heteroaromatic Construction

Edward A. Anderson of the University of Oxford rearranged the alkynyl oxirane 1 to the furan 2 (ACS Catal. 2018, 8, 8290. ). Rulong Yan of Lanzhou University nitrated 3, leading to the nitrofuran 4 (Org. Biomol. Chem. 2018, 16, 5232. ). Yan He of Henan Normal University coupled 6 with 5 to give 7 (J. Org. Chem. 2018, 83, 12514. ). Zi-Sheng Chen and Kegong Ji of Northwest A&F University oxidized 8 with 9 to give the furan 10 (Org. Lett. 2018, 20, 4622. ).

David Milstein of the Weizmann Insitute of Science assembled the pyrrole 13 by combining 11 with 12 under seven atmospheres of ammonia (J. Am. Chem. Soc. 2018, 140, 11931. ). Debasis Banerjee of the Indian Institute of Technology Roorkee described a related procedure (J. Org. Chem. 2018, 83, 15406. ). Pan-Lin Shao of the Southern University of Science and Technology and Yixin Lu and Yu Zhao of the National University of Singapore used a designed phosphine to mediate the addition of 15 to 14, leading to 16 in high ee (Chem. Eur. J. 2018, 24, 10513. ). Mei-Xiang Wang of Tsinghua University cylized the aldehyde 17 to the pyrrole 18 (Org. Chem. Front. 2018, 5, 3138. ). Ketones such as 19 are readily prepared by Achmatowicz rearrangement of furans. Aurelio G. Cśak  of the Universidad Complutense coupled 19 with 20 and then benzylamine, leading to the pyrrole 21 (J. Org. Chem. 2018, 83, 11425. ).

Laurel L. Schafer of the University of British Columbia added 23 to 22, then combined that product with 24 to give, after oxidation, the pyridine 25 (Org. Lett. 2018, 20, 6663. ). Rick L. Danheiser of MIT cyclized 26 in the presence of tosyl cyanide, leading to 27. The sulfone of 27 was readily displaced by other nucleophiles (Org. Lett. 2018, 20, 6244. ).

Zheng-Hui Guan of Northwest University found mild conditions for the cyclization of the oxime acetate 28 to the azirine 29 (Org. Biomol. Chem. 2018, 16, 4333. ). Such azirines are readily convertible to indoles by thermolysis (Preparation of Heteroaromatic Derivatives 2006, October 16) or under Rh or Fe (Heteroaromatic Construction: The Fukuyama Synthesis of Tryprostatin A 2011, June 20) catalysis. Andrea Penoni of the UniversitÓ degli Stui dell'Insubria assembled the indole 32 by combining 30 with 31 (Org. Biomol. Chem. 2018, 16, 6853. ). Jason M. Lyman, Richard J. K. Taylor and William P. Unsworth of the University of York cyclized 33 to 34 (ACS Catal. 2018, 8, 6844. ). Wei Chen and Sunliang Cui of Zhejiang University added the acid 36 to the enamide 35, to give an intermediate that cyclized to 37 (Org. Chem. Front. 2018, 5, 3574. ).

D. F. Taber, Org. Chem. Highlights 2019, June 17.
URL: https://www.organic-chemistry.org/Highlights/2019/17June.shtm