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1. Due to its unique C-C and C-H bonding properties, conformational preferences and relative hydrophilicity, the cyclopropyl ring has been used as a synthetic building block in drug discovery to modulate potency and drug-like properties. During an effort to discover inhibitors of the hepatitis C virus non-structural protein 5B with improved potency and genotype-coverage profiles, the use of a pyrimidinylcyclopropylbenzamide moiety linked to a C6-substituted benzofuran or azabenzofuran core scaffold was explored in an effort to balance antiviral potency and metabolic stability. 2. In vitro metabolism studies of two compounds from this C6-substituted series revealed an NADPH-dependent bioactivation pathway leading to the formation of multiple glutathione (GSH) conjugates. Analysis of these conjugates by LC-MS and NMR demonstrated that the cyclopropyl group was the site of bioactivation. Based on the putative structures and molecular weights of the cyclopropyl-GSH conjugates, a multi-step mechanism was proposed to explain the formation of these metabolites by P450. This mechanism involves hydrogen atom abstraction to form a cyclopropyl radical, followed by a ring opening rearrangement and reaction with GSH. 3. These findings provided important information to the medicinal chemistry team which responded by replacing the cyclopropyl ring with a gem-dimethyl group. Subsequent compounds bearing this feature were shown to avert the bioactivation pathways in question.

Aryl aminoacetonitriles are oxidized by NiO 2 –H 2 O or MnO 2 in the presence of a wide range of NH 2 -containing compounds to afford aryl amidines, presumably via iminium intermediates. A ‘one-pot’ procedure for the preparation of heteroaryl amidines from N -containing heteroaryl halides through a process comprising sequential S N Ar substitution and oxidation has also been developed.

The S N Ar-type reaction of the piperidine amide of cyanoacetic acid with a series of heteroaryl halides followed by in situ oxidation of the resultant anion with peracetic acid provided a convenient, one-pot protocol for preparative access to heteroaryl α-keto amides. In this procedure, the amide of cyanoacetic acid functions as an Umpolung-type synthon of the α-keto amide moiety.

Malononitrile could be utilized as a synthon for the carbonyl moiety via a one-pot process that was initiated via base-mediated S N Ar substitution of a heteroaryl halide. Subsequent peracetic acid oxidation of the resultant anion delivered an electrophilic acyl nitrile in situ that readily reacted with added nucleophiles to afford heteroaryl carboxylic acid derivatives. The reaction of the sodium salt of malononitrile with a series of heteroaryl chlorides followed by the subsequent addition of an amine and peracetic acid provided the corresponding heteroaryl amides.

Conditions for attachment of acetyl chloride, benzoyl chloride, and chloromethyl oxalate to the 3-position of 4-, 5-, 6-, or 7-azaindoles were explored. Best results were achieved with an excess of AlCl(3) in CH(2)Cl(2) followed by the addition of an acyl chloride at room temperature.