Synthesis of Multisubstituted Allenes, Furans, and Pyrroles via Tandem Palladium-Catalyzed Substitution and Cycloisomerization.

A palladium-catalyzed propargyl substitution reaction of propargyl acetates with indium organothiolates is developed for the synthesis of multisubstituted allenyl sulfides. This procedure can be applied to the synthesis of multisubstituted furans and pyrroles via tandem palladium-catalyzed propargyl substitution and cycloisomerization reaction in one pot.

Synthesis of Acyl Alkenylindium Reagents and Their Application in the Synthesis of (Z)-α,ß-Unsaturated Ketones via Palladium-Catalyzed Cross-Coupling Reaction.

A synthetic method for the preparation of acyl alkenylindium reagents was developed involving the hydroindation reaction of allenyl ketones with indium and indium chloride in methanol under mild conditions. Their synthetic applications were demonstrated from Pd-catalyzed cross-coupling reactions with aryl bromides and iodides and alkenyl and aryl triflates for the synthesis of (Z)-α,ß-unsaturated ketones.

Synthesis of pyrroles from terminal alkynes, N-sulfonyl azides, and alkenyl alkyl ethers through 1-sulfonyl-1,2,3-triazoles.

A method for synthesis of substituted pyrroles has been developed. 1-Sulfonyl-1,2,3-triazoles generated from terminal alkynes gave α-imino rhodium carbene complexes, which when reacted with alkenyl alkyl ethers afforded substituted pyrroles. The method can be efficiently applied to a one-pot sequential reaction starting from terminal alkynes.

ICl-mediated intramolecular twofold iodoarylation of diynes and diynyl diethers and amines: synthesis of bis(2H-hydronaphthalene and chromene) and 2H-quinoline bearing an alkenyl iodide moiety.

Electrophilic intramolecular twofold iodoarylation was developed from the reaction of diynes and diynyl diethers and amines with iodine monochloride under mild conditions, which produced bis(2H-hydronaphthalene and chromene) and 2H-quinoline bearing an alkenyl iodide moiety in good to excellent yields. These compounds underwent Pd-catalyzed cross-coupling reactions with arylboronic acid and indium tris(arylthiolate) to produce the functionalized styrene derivatives.

Palladium-catalyzed C(sp2 and sp3)-H activation/C-O bond formation: synthesis of benzoxaphosphole 1- and 2-oxides.

An efficient synthetic method of benzoxaphosphole 1- and 2-oxides is reported from phosphonic and phosphinic acids without prefunctionalization through a Pd-catalyzed C(sp(2) and sp(3))-H activation/C-O bond formation under aerobic conditions.

Gold-catalyzed sequential alkyne activation for the synthesis of 4,6-disubstituted phosphorus 2-pyrones.

Tandem gold-catalyzed addition of alkynyl phosphonic acid monoethyl esters to terminal alkynes and cyclization were developed for the synthesis of 4,6-disubstituted phosphorus 2-pyrones in one reaction vessel based on the concept of sequential alkyne activation. Alkynyl enol phosphonates were selectively obtained through the gold-catalyzed addition reaction in the presence of a catalytic amount of triethylamine. Also, gold-catalyzed cyclization of alkynyl enol phosphonates was successful in giving a variety of 4,6-disubstituted phosphorus 2-pyrones.

Synthesis of indenes via Brønsted acid catalyzed cyclization of diaryl- and alkyl aryl-1,3-dienes.

Substituted indenes can be synthesized via the Brønsted acid catalyzed cyclization of diaryl- and alkyl aryl-1,3-dienes. In this approach, treatment of symmetric or unsymmetric diaryl- and alkyl aryl-1,3-dienes with a catalytic amount of trifluoromethanesulfonic acid gives a variety of indene derivatives in good to excellent yields under mild conditions.

Hybrid system of metal/Brønsted acid relay catalysis for the intramolecular double hydroarylation and cationic cyclization of diyne diethers and diamines.

We have developed a hybrid system of metal/Brønsted acid relay catalysis for the intramolecular double hydroarylation and cationic cyclization of diyne diethers and diamines to give 4,4'-bi(2H-chromene), bi(2H-quinoline), and dioxafluoranthenes starting from 2,4-diyne-1,6-diethers and diamines in one reaction vessel under mild conditions.

Preparation of ethyl 2-aryl 2,3-alkadienoates via palladium-catalyzed selective cross-coupling reactions.

Pd-catalyzed cross-coupling reactions of aryl iodides containing not only an electron-donating group but also an electron-withdrawing group on the aryl ring with organoindium reagents generated in situ from indium and ethyl 4-bromo-2-alkynoates produced selectively ethyl 2-aryl-2,3-alkadienoates in good yield.

Synthesis of 2-alkyl- and aryl-3-ethoxycarbonyl-2,5-dihydrofurans through gold-catalyzed intramolecular hydroalkoxylation.

Treatment of a wide range of functionalized hydroxyallenic esters with 5 mol % Ph(3)PAuCl and 5 mol % AgOTf in CH(2)Cl(2) at 25 °C for 1 h produced selectively 2-alkyl- and aryl-3-ethoxycarbonyl-2,5-dihydrofurans in good to excellent yield through intramolecular hydroalkoxylation by a 5-endo mode.