Room-Temperature Ligand-Free Pd/C-Catalyzed C–S Bond Formation: Synthesis of 2-Substituted Benzothiazoles

Abstract

The synthesis of 2-substituted benzothiazoles has been achieved via cyclization of o-iodothiobenzanilide derivatives using Pd/C as the catalyst at room temperature. The protocol is ligand-free, additive-free, and high-yielding and involves very mild conditions.

Quinolines Formation by Condensation of Heteroaromatic Ketones and 2‐Aminobenzophenones under MW Irradiation

“…Dibenzo[b,f] [1,5]diazocines have drawn the attention of organic chemists since the 1960s due to antiviral, cholesterol-lowering and hormone-like activity. 13,14 Moreover, their reversible conformational changes during electrochemical redox processes make them interesting building blocks for molecular machines and artificial muscles. 15 Conventional synthesis methods preparing dibenzo[b,f] [1,5]diazocines required long reflux times, 16,17 which in this paper was dramatically changed to solvent-less, no-heat-required, and 3 min reaction.…”

Novel Route to 4‐(Adamantan‐1‐yl)quinoline Derivatives Based on the Friedländer Condensation

“…Measurements were performed with an amaZon X ion-trap mass spectrometer (Bruker Daltonics, D-Bremen). Individual samples (in concentrations of 500 ng ml À1 ) were infused into (5) 7.3987 (4) 18.2637 (10) 8.7232 (2) b [] 11.0027 (6) 6.6195 (2) 12.8276 (5) 12.4704 (8) 10.0058 (3) c [] 12.6351 (7) 20.4905 (8) 11.7675 (5) 32.8132 (18 .0 l · min À1 ; nebulizer pressure, 55.16 kPa. N 2 was used for nebulizing as well as drying gas.…”

“…13 C-NMR: 14.1 (MeCH 2 ); 23.9 (MeÀC(2)); 29.4 (CH(Ad)); 37.0 (CH 2 (Ad)); 41.6 (C(Ad)); 41.8 (CH 2 (Ad)); 61.7 (MeCH 2 ); 124.5 (CH); 124.9 (C); 127.0 (C); 127.8, (CH); 128.8 (CH); 130.8 (CH); 148.7 (C); 151.1 (C); 155.0 (C); 171.9 (C¼O). GC/MS (t R 29.8 min): 350 (7), 349 (30, M þ ), 348 (8), 305 (23), 304 (100), 303 (12), 276 (7), 246 (6) (Ad)); 2.20 (m, 3 CH(Ad)); 2.55 (m, 3 CH 2 (Ad)); 2.80 (m, CH 2 (5)); 3.43 (m, CH 2 (6)); 7.25 (d, J ¼ 7.5, 1 H); 7.38(m, 2 H); 7.43 (dd, J ¼ 7.5, 1 H); 7.57 (dd, J ¼ 7.5, 1 H); 8.21 (br. s, 1 H); 8.42 (d, J ¼ 6.9, 1 H); 8.58 (d, J ¼ 8.7, 1 H).…”

“…In this article, we describe a new convenient synthetic route to various novel 2,3,4trisubstituted quinolines bearing an adamantan-1-yl moiety at C(4) via the Friedländer condensation (for reviews, see [12]) from adamantan-1-yl 2-aminophenyl ketone/ adamantan-1-ylmethyl 2-aminophenyl ketone and the corresponding carbonyl compounds.…”

Novel 2‐Arylbenzothiazoles: Selective Chromogenic and Fluorescent Probes for the Detection of Picric Acid

“…Many synthetic protocols have been developed for the condensation of 2‐aminobenzenethiol with different precursors such as carboxylic acids, esters, nitriles, alcohols, aldehydes, aryl ketones, etc for the synthesis of 2‐arylbenzothiazoles. Most of the transformations require the use of metal catalysts,, high temperature, longer reaction hours and limited substrate scope. Even the presence of trace amount of catalysts containing metal complex along with any other toxic reagent in biologically active precursors can cause severe health problems as 2‐arylbenzothiazoles are also useful for blocking neurotransmission and as neuroprotective agents .…”