Rice husk ash supported FeCl2·2H2O: A mild and highly efficient heterogeneous catalyst for the synthesis of polysubstituted quinolines by Friedländer heteroannulation

Abstract

Rice husk ash was used as a new, green, and cheap adsorbent for FeCl3. Characterization of the obtained reagent showed that rice husk ash supported FeCl2•2H2O was formed. This reagent is efficient at catalyzing the synthesis of multisubstituted quinolines by the Friedländer heteroannulation of o-aminoaryl ketones with ketones or β-diketones under mild reaction conditions. This methodology allows for the synthesis of a broad range of substituted quinolines in high yields and with excellent regioselectivity in the absence of a solvent.

Environmentally Friendly Nafion-Mediated Friedländer Quinoline Synthesis under Microwave Irradiation: Application to One-Pot Synthesis of Substituted Quinolinyl Chalcones

“…43-7.38 (m, 3 H), 7.19-7.15 (m, 3 H), 2.74 (s, 3 H). 36,148.31,147.26,133.97 (d,J = 3.25 Hz),131.05 (d,J = 8.125 Hz,2×),129.25,129.02,125.74,125.21,124.90,122.12,115.45 (d,J = 21.375…”

Advances in polymer based Friedlander quinoline synthesis

“…Although the method seems conventional with use of solvent, longer reaction times and less economic yields, but it has described the new modified Friedlander approach with the use of Pd/C as a catalyst. 1) as a catalyst for the synthesis of multisubstituted quinolines by the Friedlander heteroannulation under solvent free conditions [47]. The method highlighted the entry of new carbon supported catalyst with excellent yields of products, short reaction times and reusability of catalyst for three cycles with negligible loss of activity.…”

Formation of Synthetically Versatile 2-Aminobenzophenones from Readily Accessed Acyl Hydrazides

“…Compounds bearing this structure have displayed desirable pharmacological use as antimitotic, antitumor, and antiproliferative agents, as well as skeletal muscle relaxants . 2-Aminobenzophenones are also useful starting materials for the synthesis of a wide variety of fine chemicals such as acridones, quinolines, − quinazolines, − quinolinones, quinoxalinones, fluorenones, benzisoxazoles, indazoles, indoles, 2-quinazolinones, benzothiophenes, diaryldibenzodiazocines, and (perhaps most noteworthy) benzodiazepines. − As such, various methodologies for the synthesis of 2-aminobenzophenones and their derivatives have been developed, including (i) Friedel–Crafts acylation of para-substituted anilines; , (ii) reaction of 2-aminobenzaldehydes with aryl Grignard reagents followed by oxidation with CuCl 2 ; (iii) Pd-catalyzed addition of arylboronic acids or sodium arylsulfinates to 2-aminobenzonitriles; (iv) Pd-catalyzed C–H bond coupling of ortho-directed anilines; and (v) aryl insertion into the C–N of amides or imides . Unfortunately, however, many of these processes suffer from either poor substrate scope (e.g., Friedel–Crafts processes falter when utilizing electron-poor arenes), require multiple reaction steps (e.g., the Grignard-based route obviates the presence of acidic protons and requires product oxidation to obtain the ketone), or require the use of expensive metal catalysts (e.g., Pd­(OAc) 2 , Pd­(TFA) 2 ).…”