Sequential Pd- and Rh-catalyzed three-component cyclization with allenylboronate platform.

[reaction: see text] A novel three-component cyclization using allenylboronate ester is described. A three-component assembly of allenylboronate ester, aryl iodides, and stabilized carbon nucleophiles took place in the presence of palladium catalyst, furnishing functionalized alkenylboronate esters with high regio- and stereoselectivity. A Rh-catalyzed cyclization of the resultant three-component products then afforded interesting carbocyclic frameworks efficiently.

Catalytic four-component assembly based on allenylboronate platform: new access to privileged allylic amine structures.

We developed a novel palladium-catalyzed four-component assembly based on allenylboronate platform, by which privileged allylic amine structures can be constructed in a regioselective, stereoselective, and diversity-oriented manner. The boryl group acts not only as a useful group that can be transformed to various functional groups afterward but also as a stereochemical controller in the generation of key (pi-allyl)palladium intermediates. A short synthesis of rolipram (selective phosphodiesterase-4 inhibitor) is also demonstrated.

Synthesis of isoquinoline derivatives using ROM-RCM of cyclobutene-yne.

Isoquinoline derivatives were synthesized from cyclobutenylmethylamine derivatives having an alkyne moiety in a tether using a second-generation ruthenium carbene complex under ethylene gas in good yields.

Rapid construction of multisubstituted olefin structures using vinylboronate ester platform leading to highly fluorescent materials.

[reaction: see text] A catalytic one-pot triarylation on the C=C core of vinylboronate pinacol ester (1) produces extended pi-systems based on a multisubstituted olefin structure very rapidly. We established an efficient protocol for the Pd-catalyzed double C-H arylation of 1 with aryl halides, which was successfully integrated with C-B arylation with aryl halides (cross-coupling) in one pot. By using this method, several highly fluorescent materials with a wide range of color variations (blue to red) were discovered.

Syntheses of anolignans A and B using ruthenium-catalyzed cross-enyne metathesis.

Anolignans A and B were synthesized using ruthenium-catalyzed cross-enyne metathesis as the key steps. The 1,3-diene moieties of these natural products were constructed by the introduction of the methylene parts of ethylene into alkyne using Grubbs' catalyst.