Heteroaromatics: The Šačus/Opatz Synthesis of Lamellarin G Trimethyl Ether

Lutz Ackermann of the Georg-August-Universität Göttingen assembled the furan 4 by the photochemically-promoted three-component coupling of the aldehyde 1, the acid chloride 2 and ethyl acrylate 3 (Chem. Sci. 2023, 13, 7256. DOI: 10.1039/D2SC02277J). Ana T. Carmona and Antonio J. Moreno-Vargas of the University de Sevilla showed that the Diels-Alder product between the bromoalkyne 5 and furan 6 on exposure to the tetrazine 7 was converted to the furan 8 (J. Org. Chem. 2023, 88, 13331. DOI: 10.1021/acs.joc.3c01145).

Thomas J. J. Müller of the Heinrich-Heine-Universität Düsseldorf devised the sequential combination of the alkyne 10 with the acid chloride 9, then benzyl amine, then the nitroalkene 11 to form the pyrrole 12 (Synlett 2023, 34, 1781. DOI: 10.1055/a-2077-4955). Lei Dai and Yixin Lu of the National University of Singapore prepared the pyrrole 16 by combining the pyrrole 13 with the enamine 14 in the presence of the phosphoric acid catalyst 15 (ACS Cent. Sci. 2023, 9, 1758. DOI: 10.1021/acscentsci.3c00812).

Shuming Chen of Oberlin College and Jiajia Ma of Shanghai Jiao Tong University established conditions for the Birch reduction of the quinoline 17 to the pyridine 18 (Angew. Chem. Int. Ed. 2023, 62, e202312203. DOI: 10.1002/anie.202312203). Mikhail V. Polynski, now also at the National University of Singapore, and Maria S. Ledovskaya of Saint Petersburg State University used calcium carbide to generate acetylene, that then added to the 1,2,3-triazine 19, leading to the pyridine 20 (Chem. Asian. J. 2023, 18, e202300781. DOI: 10.1002/asia.202300781). Young Taek Han of Dankook University cyclized the coumarin 22 to the pyridine 23 (J. Org. Chem. 2023, 88, 15473. DOI: 10.1021/acs.joc.3c01654). Mark D. Levin of the University of Chicago converted the aryl azide 23 to the pyridine 26 by reaction with the amino alcohol 24 followed by the N-bromolactam 25 (Science 2023, 381, 1474. DOI: 10.1126/science.adj5331).

Johannes M. Wahl of Johannes-Gutenberg Universität Mainz demonstrated that the cyclobutanol 27, readily prepared by photoisomerization of 2-methylacetophenone, on treatment with the hydroxylamine sulfonate 28 was converted to the indole 29 (Org. Lett. 2023, 25, 5795. DOI: 10.1021/acs.orglett.3c02048). Jianchao Liu of Jiangxi Normal University achieved high diastereoselectivity in the preparation of the indolyl-C-glycoside 31 by combination of the 2-alkynyl aniline 30 with the glucal 31 (Org. Lett. 2023, 25, 7170. DOI: 10.1021/acs.orglett.3c02688). Xiaowei Dou of China Pharmaceutical University induced high enantioselectivty in the preparation of the indole 34 from the prochiral cyclopenten-1,4-dione and the ortho-amino phenylboronic acid 33 (Chem. Sci. 2023, 14, 7980. DOI: 10.1039/D3SC02474A). Chang Guo of the University of Science and Technology of China used a dual catalyst system to mediate the enantioselective construction of the indole 37 by the combination of the alkyne 35 with the β-ketoester 36 (Angew. Chem. Int. Ed. 2023, 62, e202305638. DOI: 10.1002/anie.202305638).

The lamellarins, first isolated from marine prosobranch molluscs of the genus Lamellaria, show a wide range of biological activity, including inhibition of protein kinases. Algirdas Šačus of Kaunas University of Technology and Till Opatz, also of the Johannes-Gutenberg Universität Mainz assembled lamellarin G trimethyl ether (41) via the preparation of the pyrrole 40 by the acylation of the iminium salt 38 with the HOBt-ester 39 (Org. Biomol. Chem. 2023, 21, 5997. DOI: 10.1039/D3OB00870C).