C-Aminoimidoylation and C-Thiocarbamoylation of Esters, Sulfones, and Ketones

Abstract

Esters, sulfones, and ketones were C-aminoimidoylated and C-thiocarbamoylated by benzotriazole-1-carboxamidines 8a-g and 1-(alkyl-or-arylthiocarbamoyl)benzotriazoles 9a-i, respectively. The present work represents the first systematic approach to these compound classes, the few previously known examples of which were obtained by diverse approaches.

Synthesis of Heterocycles Mediated by Benzotriazole. 1. Monocyclic Systems

“…1-( N -benzylthiocarbamoyl)benzotriazole ( 427 ) is prepared from benzylamine and bisbenzotriazol-1-ylmethanethione in 97% yield . The isothiocyanate anion generated from 427 by 2 molar equiv of potassium tert -butoxide adds to carbonyl groups of ketones to generate oxazolidinethiones 428 , which are isolated in 27% (R = Ph) to 51% (R = 2-thienyl) yields (Scheme ) …”

1,2,3-Triazoles

“…Novel applications of benzotriazole methodology in organic synthesis include regiospecific preparation of 1,4,5-trisubstituted pyrazoles <2007ARK(i)9> , efficient synthesis of 1,5-disubstituted tetrazoles <2007SL1204> , amidoalkylations of nitroalkanes, nitriles, alkynes, and esters <2007ARK(xi)96> , thioamidoalkylation of 1,3-dicarbonyl compounds, enol silyl ethers, and enamines <2007S1655> , C-aminoimidoylation and C-thiocarbamoylation of esters, sulfones, and ketones <2007JOC6742> , synthesis of cyano derivatives of N -alky and N -aryl piperazines <2007EJM471> , and preparation of polyfunctional acyl azides <2007JOC5802> . N -Acyl derivatives of benzotriazole are used for efficient peptide coupling of sterically hindered aminoacids <2007JOC5794> and 5-amino-1-methyl-1 H -[1,2,4]-triazole-3-carboxylic acid <2007SC1917 , expedient synthesis of N-Z -pyroglutamyl-aminoacid derivatives <2007BML6000> , synthesis of (+)-aphanorphine <2007H(72)497> , and as Mosher-Bt reagents <2007JOC4268> .…”

Imidoylation reactions at carbon

“…36 Recently, Caminoimidoylation of esters from the reaction of their enolates with benzotriazole-1-carboxamidines 34 was achieved at 20 °C to produce 37 in 20-63% yields (Scheme 14). 35 The predominant tautomeric structures of amidines 37 (Scheme 14) were determined by 2D NMR.…”

“…35 However, application of this method is limited; It was only successful with alkyl phenyl sulfone 39. …”