A Highly Effective One-Pot Synthesis of Quinolines from 2-Alkynylnitrobenzenes

Abstract

A highly effective one-pot synthesis of poly-substituted quinolines from 2-alkynylnitrobenzenes using inexpensive reagents has been developed. Reaction of 2-alkynylnitrobenzenes with Sn/HCl in EtOH resulted in the formation of 2-aminophenyl ketones and subsequently condensed in situ with ketones to form tri-substituted quinolines in 80-97% yields. 93 73 75 84 a) The reaction was carried out in the absence of Na 2 S (8% of 2-phenylindole was obtained as a side product). Simple 2-aminophenylethanones, such as 2-aminoacetophenone and 2-aminobenozophenone, were commercially available; however, few reports on the synthesis of more complicated 2-aminophenyl

Metal‐Free and syn‐Selective Hydrohalogenation of Alkynes through a Pseudo‐Intramolecular Process

“…In contrast, the tert-butyl group is bulky enough to prevent anti-addition; however, attack of the chloride was also suppressed to undergo the competitive hydration, leading to 4 j. [18] The silyl group is also bulky and undergo competitive hydration; however, desilylation occurred under the employed conditions to give chloroalkene 2 h and 2-acetylaniline (4 h) [19] in 48 % and 50 % yields, respectively (entry 5). Functionalized ethynylaniline 1 l could also be employed to furnish 2 l as a mixture of E/Z isomers due to the small size of the hydroxymethyl group (entry 6).…”

“…)aniline (4 j): [18] Orange oil (6.9 mg, 0.04 mmol, 18 %). 1 H NMR (400 MHz, CDCl 3 ) δ 7.83 (dd, J = 1.6, 8.8 Hz, 1H), 7.23 (ddd, J = 1.2, 6.8, 6.8 Hz, 1H), 6.63 (dd, J = 1.6, 8.8 Hz, 1H), 6.61 (ddd, J = 1.2, 6.8, 6.8 Hz, 1H), 2.81 (s, 2H), 1.06 (s, 9H); 13 C NMR (100 MHz, CDCl 3 ) δ 30.2 (CH 3 ), 31.7 (C), 50.5 (CH 2 ), 115.5 (CH), 117.3 (CH), 119.6 (C), 131.9 (CH), 133.9 (CH), 150.3 (C), 203.1 (C); IR (ATR/cm À 1 ); HRMS(ESI/TOF): calcd.…”

Copper‐ and Phosphane‐Free Sonogashira Coupling of Arenediazonium o‐Benzenedisulfonimides

“…4‐Methoxy‐2‐nitro‐1‐(2‐phenylethynyl)benzene (4i): This compound has been reported in the literature,21 but no physical or spectroscopic data were included. Pale yellow solid (0.47 g, 92 %), m.p.…”

The First Formation of (1Z)‐1‐Alkylidene‐1H‐isobenzofuranium Amides and 1H‐Inden‐1‐ones: Acid‐Promoted 5‐exo Cyclization and Hydration/Aldol Condensation Reactions of o‐Ethynylbenzophenones

“…Furthermore, the reaction mechanism was also supported by previous research into protonation of phenylacetylene to give vinyl cationic species15 and into selective Tf 2 NH‐catalyzed hydration of internal alkynes 16. Numerous reports on the acid‐catalyzed hydration of internal alkynes have appeared; most of them require severe reaction conditions, such as formic acid at 100 °C for 60 h,17a PTSA/EtOH at 78 °C for 60 h,17b Tf 2 NH at 100 °C for 40 h,16 or HCl/EtOH at reflux for 8 h 17c. In contrast, we found that this transformation of o ‐ethynylbenzophenones into 1 H ‐inden‐1‐ones could be smoothly carried out under mild conditions.…”