Heteroaromatic Construction: The Newhouse Synthesis of (-)-Xylogranatopyridine B
Doron Pappo of the Ben-Gurion University of the Negev assembled the furan 3 by combining the sulfoxide 2 with the β-keto ester 1 (J. Org. Chem. 2018, 83, 723. DOI: 10.1021/acs.joc.7b02708). Claude Spino of the Université de Sherbrooke added 5 to 4 to give an intermediate lactone, to which the Grignard reagent 6 was added, leading to 7 (J. Org. Chem. 2018, 83, 5609. DOI: 10.1021/acs.joc.8b00613).
Lingyan Liu and Jing Li of Nankai University cyclized the alkyne 8 to the pyrrole 9 (Chem. Asian J. 2018, 13, 46. DOI: 10.1002/asia.201701386). George E. Kostakis of the University of Sussex and Ioannis N. Lykakis of the Aristotle University of Thessaloniki prepared the pyrrole 13 by the combination of 10, 11, and 12 (J. Org. Chem. 2018, 83, 2104. DOI: 10.1021/acs.joc.7b03051).
In the course of a synthesis of lycopladine A, Fayang G. Qiu of the Guangzhou Institute of Biomedicine and Health used the Katritzky protocol, the addition of 15 to the enone 14, to prepare the pyridine 16 (Chem. Commun. 2018, 54, 3598. DOI: 10.1039/C8CC01626G). Hongchao Guo of China Agricultural University constructed the pyridine 19 by adding 17 to 18 (Chem. Sci. 2018, 9, 1831. DOI: 10.1039/C7SC04515H). Yong Rok Lee of Yeungnam University opened the 3-formylchromone 20 with the alkyne 21 to give the pyridine 22 (Adv. Synth. Catal. 2018, 360, 751. DOI: 10.1002/adsc.201701137).
Mitsuhiro Yoshimatsu of Gifu University prepared 23 by adding nitromethane to the corresponding nitrile. Addition of the enone 24 led to the pyridine 25 (Org. Lett. 2018, 20, 1130. DOI: 10.1021/acs.orglett.8b00058).
In an elegant illustration of borrowed hydrogen, Rafael Ballesteros-Garrido of the Universidad de Valencia used ethylene glycol 27 to convert the aniline 26 to the indole 28 (J. Org. Chem. 2018, 83, 521. DOI: 10.1021/acs.joc.7b02722). Extending the Catellani protocol to an aziridine 30, Yong-Min Liang of Lanzhou University and Siwei Bi of Qufu Normal University converted 29 to the indoline 31 (Chem. Commun. 2018, 54, 3407. DOI: 10.1039/C8CC01062E). Rai-Shung Liu of the National Tsing-Hua University added the allene 33 to nitrosobenzene (32), leading to the indole 34 (Org. Lett. 2018, 20, 1038. DOI: 10.1021/acs.orglett.7b03985). Thomas Magauer of Leopold-Franzens University added the oxime 35 to the alkyne 36 to give an intermediate that rearranged to the indole 37 (Chem. Eur. J. 2018, 24, 1455. DOI: 10.1002/chem.201705662).
Xylogranatopyridine A, which showed inhibitory activity against protein tyrosine phosphatase 1B, and the closely related xylogranatopyridine B (41) were isolated from the twigs and leaves of the Chinese mangrove Xylocarpus granatum. A key step in the synthesis of 41 developed by Timothy R. Newhouse of Yale University was the construction of the pyridine 40 by the coupling of 38 with 39 (J. Am. Chem. Soc. 2018, 140, 2062. DOI: 10.1021/jacs.7b13189).