Cycloisomerization – a straightforward way to benzo[h]quinolines and benzo[c]acridines
作者:Aleksandr N. Shestakov、Alena S. Pankova、Mikhail A. Kuznetsov
DOI:10.1007/s10593-017-2179-5
日期:2017.10
Cycloisomerization of 3-alkynyl-2-arylpyridines and quinolines offers a straightforward approach to benzo[h]quinolines and benzo[c]-acridines. Substituent at the triple bond governs a choice between transition metal or Brønsted acidcatalysis. A direct electrophilic activation by trifluoromethanesulfonic acid induces an almost quantitative cyclization of the o-aryl(phenylethynyl) fragment. PtCl2 efficiently
3-炔基-2-芳基吡啶和喹啉的环异构化为苯并[ h ]喹啉和苯并[ c ] -ac啶提供了一种直接的方法。在三键处的取代基决定过渡金属催化或布朗斯台德酸催化之间的选择。三氟甲磺酸的直接亲电子活化引起邻-芳基(苯基乙炔基)片段的几乎定量环化。PtCl 2有效催化2-芳基-3-乙炔基戊烯的环化。
Syntheses of Benzofuranoquinolines and Analogues via Photoinduced Acceptorless Dehydrogenative Annulation of <i>o</i>-Phenylfuranylpyridines
strategy for the syntheses of benzofuranoquinolines and its analogues via the irradiation of o-phenylfuranyl/thienylpyridines/pyrimidines in DCM with UV light at rt under an argon atmosphere is described. The mechanism of this reaction through the process of 6π-electrocyclization, [1,5]-hydrogen shift, and 1,3-eneamine tautomerism leading to H2 evolution was elucidated. Notably, the syntheses of cis-8b-methyl-8b
2,3- and 2,5-Dibromopyridines reacted with arylboronic acids, catalyzed by Pd(OAc)(2)/PPh3 in the presence of K2CO3 in CH3CN/MeOH (2:1) at 50 degrees C for 24 h, to afford 2-aiylpyridines in good to high yields, while 2,4-dibromopyridine reacted with arylboronic acid pinacol esters, catalyzed by Pd(OAc)(2)/PPh3 in the presence of KOH in CH3CN at 70 degrees C for 24 h, to afford 2-arylpyridines in good to high yields. To expand this methodology, a 170-HSD1 inhibitor was synthesized in good yield. (C) 2013 Elsevier Ltd. All rights reserved.