Dongjin Kang

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.

Synthesis of naphthalenes via platinum-catalyzed hydroarylation of aryl enynes.

An efficient synthetic method of functionalized naphthalenes having hydrogen, alkyl, alkenyl, aryl, or heteroaryl groups on the 4-position and ethoxycarbonyl group on the 2-position was developed through selective Pt-catalyzed 6-endo intramolecular hydroarylation of ethyl (E)-2-ethynyl/alkynyl cinnamates.

Synthesis of Substituted Coumarins via Brønsted Acid Mediated Condensation of Allenes with Substituted Phenols or Anisoles

Coumarins were obtained from the condensation of electron-rich arenes with allenes in the presence of TfOH in good yield. Depending on the substituent pattern of allenes employed, the general synthetic method of 4-substituted and 3,4-disubstituted 3-arylcoumarins has been developed. Readily available allenes were employed as the three-carbon atom sources constituting the coumarin skeleton.

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.

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.

Trifluoromethanesulfonic Acid Catalyzed Isomerization of Kinetic Enol Derivatives to the Thermodynamically Favored Isomers

Trifluoromethanesulfonic acid catalyzed isomerization of kinetic enol derivatives to the thermodynamically favored isomers was developed. Under the present conditions, kinetic enol phosphates, enol acetates and benzoates, and enol sulfonates were smoothly isomerized to produce the corresponding thermodynamically favored isomers in good to excellent yields.

Gold-catalyzed hydrosilyloxylation driving tandem aldol and Mannich reactions.

The chemoselective formation of an enolate from alkyne in the presence of a carbonyl and imine group was realized, which constructed a variety of structural motifs under exceedingly mild reaction conditions in a tandem process. Reaction driving tandem hydrosilyloxylation/aldol reactions was achieved through the formation of enol silyl ethers catalytically generated in situ from readily available alkynes. These reactions were expanded to obtain β-amino enol silyl ethers in good yields via the tandem hydrosilyloxylation/isomerization/Mannich reaction.

Synthesis of ethoxy dibenzooxaphosphorin oxides through palladium-catalyzed C(sp2)–H activation/C–O formation

Summary We report an efficient Pd-catalyzed C(sp2)–H activation/C–O bond formation for the synthesis of ethoxy dibenzooxaphosphorin oxides from 2-(aryl)arylphosphonic acid monoethyl esters under aerobic conditions.