Cephalosporins with C-7-isocyanide dihalides : useful synthons for the introduction of amino heterocycles at C-7 - new routes to the synthesis of amino imidazoles

Design and Synthesis of Potent, Selective, and Orally Bioavailable Tetrasubstituted Imidazole Inhibitors of p38 Mitogen-Activated Protein Kinase

“…Both isomers participated in the key cyclization reaction when treated with CBZ piperidine-4-carboxaldehyde and ammonium acetate in acetic acid at reflux, to afford the hydroxyimidazole 27 . Several methods are available for the reduction of hydroxyimidazoles, including P(OMe) 3 , Raney nickel-catalyzed hydrogenation, and aqueous titanium trichloride . Hydrogenation would be incompatible with the CBZ functionality and further complicated by the presence of the (methylthio)pyrimidine.…”

I2/CHP‐Mediated Oxidative Coupling of 2‐Aminobenzamides and Isocyanides: Access to 2‐Aminoquinazolinones

“…On the basis of the above results, a plausible reaction mechanism is shown in Scheme . Isocyanide 2 reacts with iodine by 1,1‐addition to give intermediate I , . The reaction of I with 2‐aminobenzamide 1 gives intermediate II by dehydrohalogenation.…”

“…Therefore, the development of an efficient strategy to construct 2‐amino‐substituted quinazolinones using an inexpensive catalyst under mild conditions is desirable. As reported in the literature, isocyanides could be converted into carbonimidic dihalides through the reaction with Br 2 , Cl 2 , or SO 2 Cl 2 , and these intermediates could then react further with nucleophiles to form heterocycles. Recently, Mirza[11b] reported an efficient synthesis of 2‐amino‐substituted quinazolinones under transition‐metal‐free conditions.…”

Cobalt‐Catalyzed Oxidative Isocyanide Insertion to Amine‐Based Bisnucleophiles: Diverse Synthesis of Substituted 2‐Aminobenzimidazoles, 2‐Aminobenzothiazoles, and 2‐Aminobenzoxazoles

“…The histamine H1-receptor V, named astemizloe, [5] and bioactive com-pounds VI and VI' [6] all contain the 2-aminobenzimidazole skeleton.There are several reported approaches to these scaffolds: 1) The addition of amines to isothiocyanates or CS 2 followed by intramolecular condensation, [7,8] 2) the cross-coupling reaction of bisnucleophiles with cyanogen bromide, [9] 3) intramolecular cyclization by C À H activation, [10] and 4) passing through the intermediate formation of isocyanide dibromides. [11] All these procedures suffer from the use of unenviromental, toxic, and/or dangerous reagents and poor step efficiency. Thus, the development of a new, general, and atom-economic method to obtain these compounds remains great challenge to chemists.Recently, reactions using isocyanide insertion (similar to carbon monoxide) have been developed for the synthesis of N-heterocycles .[12] As a continuation of our work on the insertion of isocyanide into an active NÀH bond, [13] we hope to apply this insertion strategy to the reaction of isocyanide with À SH, [14] À OH, [15] and À NH 2 [16] based bisnucleophilic reagents, such as o-aminophenols, o-aminobenzenethiol, and o-aminoanilines, for the synthesis of 2-aminobenzimidazoles, 2-aminobenzothiazoles, and 2-aminobenzoxazoles, respectively (Scheme 1).…”

“…There are several reported approaches to these scaffolds: 1) The addition of amines to isothiocyanates or CS 2 followed by intramolecular condensation, [7,8] 2) the cross-coupling reaction of bisnucleophiles with cyanogen bromide, [9] 3) intramolecular cyclization by C À H activation, [10] and 4) passing through the intermediate formation of isocyanide dibromides. [11] All these procedures suffer from the use of unenviromental, toxic, and/or dangerous reagents and poor step efficiency. Thus, the development of a new, general, and atom-economic method to obtain these compounds remains great challenge to chemists.…”