Formation of various 3-arylthioimidazoheterocycles using benign reagents and solvents with harmless by-products.

Following our previous results on an environmentally benign one-pot Sonogashira-cyclization protocol to obtain substituted furopyrimidine nucleosides under aqueous conditions, we investigate herein the Suzuki-Miyaura cross-coupling reactions of aryl and heteroaryl derivatives at the C5 position of unprotected 2'-deoxyuridine in the same media with a common catalyst system avoiding exotic ligands, since palladium acetate and triphenylphosphine afforded the expected products in moderate to good yields.

Amidomethyltrifluoroborates were successfully synthesized in a one-pot fashion and used in cross-coupling reactions with a wide variety of aryl and heteroaryl chlorides.Amidomethylarenes are commonly found in a variety of biologically active compounds (Figure 1).1 Several strategies have been developed to obtain amidomethyl-containing products such as nucleophilic displacement,2 reductive N-alkylation,3 and more commonly amidation.4 These methods follow a consonant reactivity pattern based on the nucleophilicity of the nitrogen. Recently, cross-coupling reactions using N,Ndialkylaminomethyltrifluoroborates were described to access the analogous aminomethyl moiety.5 This approach provides access to amines using a C-C bond connection strategy complementary to existing C-N bond-forming approaches.The N,N-dialkylaminomethyltrifluoroborates used in previous coupling efforts were obtained by a direct S N 2 displacement of the halides of potassium halomethyltrifluoroborates. Unfortunately, amidomethyltrifluoroborates cannot be accessed in this manner, and thus it was necessary to develop a different approach to the trifluoroborate starting materials. The strategy chosen was based on previous work pioneered by Matteson,6 in which substituted boronate esters were obtained from halomethylboronate esters via intramolecular nucleophilic displacement and one carbon homologation of in situ generated LiCHX 2 or LiCH 2 X species (X = Cl, Br, I).7 The "ate" complex resulting from initial attack of the nucleophile at the boron atom is followed by α-transfer to the neighboring carbon to form the elaborated boronate ester (Figure 2).8Amidomethylboronate esters have been synthesized following this strategy,9 but only a few examples were reported, and poor to moderate yields were observed for the formation of α-unsubstituted products in a process that required two to three steps.9f , 10 Furthermore, apart