Masahito Murai

Practical synthesis of aromatic nitriles via gallium-catalysed electrophilic cyanation of aromatic C-H bonds.

A gallium-catalysed, direct cyanation reaction of aromatic and heteroaromatic C-H bonds with cyanogen bromide was developed as a practical synthetic method for the preparation of aromatic nitriles.

A new route to 3-acyl-2-aminobenzofurans: palladium-catalysed cycloisomerisation of 2-(cyanomethyl)phenyl esters.

Treatment of 2-(cyanomethyl)phenyl esters with a catalytic amount of Pd(OAc)(2), PCy(3), and Zn afforded 3-acyl-2-aminobenzofuran derivatives in good to excellent yields, which can be used as building blocks for the synthesis of benzofuran fused heterocycles.

Gold-catalysed cycloisomerisation reactions of 2-(2-propynyl)pyridine N-oxides leading to indolizinones

Gold(I)-catalysed tandem oxygen-transfer/cycloisomerisation reaction of 2-(2-propynyl)pyridine N-oxides provides an atom-economical route to indolizinone frameworks.

Copper-catalyzed C-H cyanation of terminal alkynes with cyanogen iodide.

A copper-catalyzed reaction of terminal alkynes with cyanogen iodide (ICN) that produces alkynyl cyanides has been developed. The use of tetramethylpiperidine as a sterically congested base was successful in this reaction. Some control experiments revealed that the reaction involves the noncatalyzed formation of alkynyl iodides followed by copper-catalyzed cyanation of the iodides without the formation of copper(I) acetylide. This observation contrasts with what is normally observed in various copper-mediated reactions using terminal alkynes.

New preparation and synthetic reactions of 3,3,3-trifluoropropynyllithium, -borate and -stannane: facile synthesis of trifluoromethylated allenes, arylacetylenes and enynes.

BACKGROUND Since trifluoromethyl-containing compounds have found diverse applications in the fields of pharmaceuticals and agrochemicals, facile and selective synthetic methods for trifluoromethyl-substituted compounds are an essential tool for advanced medicinal chemistry. Now that diverse synthetic transformations of carbon-carbon triple bonds are available, 3,3,3-trifluoropropynyl-substituted compounds serve as versatile building blocks for target molecules containing trifluoromethyl groups. Thus, novel synthetic methods and reagents for incorporation of a 3,3,3-trifluoropropynyl group into an organic compound have been the major concern in exploration and modification of fluorine-based biologically active substances. RESULTS & DISCUSSION We report a preparative method of 3,3,3-trifluoropropynyllithium and its reaction with electrophiles including aldehydes, ketones, trimethoxyborane, chlorosilanes and chlorostannanes in detail. Palladium-catalyzed synthetic reactions of the carbonyl adducts and the trifluoromethyl-containing metalloid reagents are also demonstrated, which provide simple synthetic methods of trifluoromethylated allenes, arylacetylenes and enynes. The synthetic transformations presented here expand the repertoire of trifluoromethylated compounds available for medicinal scientists and contribute to the advance of future medicinal chemistry.

Copper-catalyzed addition reactions of aromatics and ketones to 2-aza-2,4-cyclopentadienone: facile and efficient transformation of carbonyl-ene-nitriles to 1H-pyrrolin-2(5H)-ones.

Copper-catalyzed reactions of carbonyl-ene-nitriles with carbon nucleophiles, such as aromatics and ketones, afforded pyrrolin-2-ones (gamma-lactam) in excellent yield. The reaction mechanism involves addition reactions with a ketimine moiety of the 2-aza-2,4-cyclopentadienone intermediate, which is formed via hydration of a nitrile moiety followed by dehydrative cyclization.

Atom-efficient synthesis of α-alkylidene-N-furylimines via catalytic vinylcarbene-transfer reactions to carbonyl-ene-nitrile compounds

The reaction of carbonyl-ene-nitrile compounds with propargyl carboxylates in the presence of a catalytic amount of PtCl(2) afforded the alpha-alkylidene-N-furylimines with high stereoselectivities.