Direct reversible decarboxylation from stable organic acids in dimethylformamide solution.

Many classical and emerging methodologies in organic chemistry rely on carbon dioxide (CO) extrusion to generate reactive intermediates for bond-forming events. Synthetic reactions that involve the microscopic reverse-the carboxylation of reactive intermediates-have conventionally been undertaken using very different conditions. We report that chemically stable C(sp) carboxylates, such as arylacetic acids and malonate half-esters, undergo uncatalyzed reversible decarboxylation in dimethylformamide solution.

N-Silylenamines as Reactive Intermediates: Hydroamination for the Modular Synthesis of Selectively Substituted Pyridines.

A modular and selective synthesis of mono-, di-, tri-, tetra-, and pentasubstituted pyridines is reported. Hydroamination of alkynes with N-silylamine using a bis(amidate)bis(amido)titanium(IV) precatalyst furnishes the regioselective formation of N-silylenamines. Addition of α,β-unsaturated carbonyls to the crude mixtures followed by oxidation affords 47 examples of pyridines in yields of up to 96%.

Regio- and Stereoselective Hydroamination of Alkynes Using an Ammonia Surrogate: Synthesis of N-Silylenamines as Reactive Synthons.

An anti-Markovnikov selective hydroamination of alkynes with N-silylamines to afford N-silylenamines is reported. The reaction is catalyzed by a bis(amidate)bis(amido)Ti(IV) catalyst and is compatible with a variety of terminal and internal alkynes. Stoichiometric mechanistic studies were also performed.

Addition of arylboronic acids to arylpropargyl alcohols en route to indenes and quinolines.

A regio- and stereoselective rhodium-catalyzed synthesis of trisubstituted allylic alcohols is described. The utility of these synthons is demonstrated in a convenient synthesis of indenes and quinolines.