α-Silylated Diazoalkynes: New Tools for Bioconjugation of Proteins.

α-Silylated diazoalkynes are stabilized diazo compounds that can selectively react with carboxylic residues in buffered aqueous media. In-situ fluoride induced desilylation increases this reactivity, leading to a very fast reaction. Application to the selective functionalization of RNase A, followed by post-functionalization using click chemistry, is described.

Rapid and Effective Synthesis of α-Acyloxy-α-alkynyltrimethylsilanes.

α-Alkynyl-α'-trimethylsilylhydrazones are readily oxidized into diazo compounds under simple experimental conditions. These stable diazo species can in turn react with a range of carboxylic acids via a protonation-nucleophilic substitution sequence, leading to valuable α-acyloxy-α-alkynyltrimethylsilanes. This procedure avoids the delicate preparation and manipulation of α-hydroxypropargyltrimethylsilanes.

Synthesis of benzocyclobutenes by palladium-catalyzed C-H activation of methyl groups: method and mechanistic study.

An efficient catalytic system has been developed for the synthesis of benzocyclobutenes by C-H activation of methyl groups. The optimal conditions employed a combination of Pd(OAc) 2 and P ( t )Bu 3 as catalyst, K 2CO 3 as the base, and DMF as solvent. A variety of substituted BCB were obtained under these conditions with yields in the 44-92% range, including molecules that are hardly accessible by other methods.