A zinc(II)-included hemicryptophane: facile synthesis, characterization, and catalytic activity.

A zinc(II)-included hemicryptophane, which has a zinc(II) center embedded in the cavity, was synthesized and characterized. The catalytic activity of the hemicryptophane was tested in the hydrolysis of methyl para-nitrophenyl carbonate (MPC). A direct comparison between the hemicryptophane and the model complex, which lacks a cavity, demonstrated that the cage structure enhanced the catalytic activity.

Platinum-catalyzed intramolecular vinylchalcogenation of alkynes with beta-phenylchalcogeno conjugated amides.

Platinum-catalyzed intramolecular vinylthiolation and -selenation of internal alkynes with vinylchalcogenides 1 having a carbamoyl group on cis-beta-position of vinyl moiety was developed. The conjugated six-membered lactam framework 2 was constructed in high yields. Density functional theory calculations for alkyne insertion processes suggest seven-membered platinacycle 3 is a kinetically favored intermediate of this catalytic system.

Carbonylation of lithium enolates with carbon monoxide mediated by selenium.

[reaction: see text] Lithium enolates of ketones and aldehydes undergo carbonylation with carbon monoxide with the aid of selenium under mild conditions to yield beta-keto and beta-formyl selenol esters after trapping with alkyl iodides. This reaction proceeds via a unique carbonylation mechanism comprised of O-carbonylation and subsequent migration of the SeCO moiety to the alpha-carbon.

Palladium-catalyzed selenoacylation of allenes leading to the regioselective formation of functionalized allyl selenides.

Palladium-catalyzed regio- and stereoselective selenoacylation of allenes with selenol esters proceeded to produce functionalized allyl selenides with the acyl moiety at the inner carbon and the SePh group at the terminal carbon in high yields. A mechanism accounting for the observed regio- and stereoselectivities is proposed based on the results of DFT calculations.

Copper(I)-catalyzed highly efficient synthesis of benzoselenazoles and benzotellurazoles.

A simple and practical useful synthetic method of 1,3-benzoselenazoles having a heteroatom substituent such as NRR', OR, and SR groups at the 2-position was developed by the copper(I)-catalyzed reaction of 2-bromophenyl (1) or 2-iodophenyl (2) isocyanides with selenium and heteroatom nucleophiles. In addition, the synthesis of 2-amino-1,3-benzotellurazoles is also described.

N-carbonylation of lithium azaenolates of amides, formamides, ureas, and carbamates with carbon monoxide mediated by selenium.

N-Carbonylation of less nucleophilic nitrogen compounds was achieved by the reaction of the lithium azaenolates with carbon monoxide and selenium. This reaction proceeds in the cases of amides, formamides, ureas, and carbamates, leading to the formation of the corresponding carbamoselenoates in good to high yields after trapping with BuI.

Palladium-catalyzed intramolecular selenocarbamoylation of alkynes with carbamoselenoates: formation of alpha-alkylidene-beta-lactam framework.

Pd-catalyzed intramolecular selenocarbamoylation of alkynes leading to alpha-alkylidene-beta-lactams was developed. This reaction can be applied to thiocarbamoylation and to the synthesis of delta- and epsilon-lactams and a cyclobutanone.

Stereoselective synthesis of new selenium-containing heterocycles by cyclocarbonylation of aminoalkynes with carbon monoxide and selenium.

The reaction of 3-aminoalkynes 2 with carbon monoxide and selenium yielded 5-alkylideneselenazolin-2-ones 3 stereoselectively via cycloaddition of in situ generated carbamoselenoates to the carbon-carbon triple bond. 4-Aminoalkyne 7 also afforded the corresponding six-membered selenium-containing heterocycle with the aid of CuI.

Selenoimidoylation of alcohols with selenium and isocyanides and its application to the synthesis of selenium-containing heterocycles.

The reaction of alcohols with selenium and isocyanides in the presence of DBU gave oxyimidoylselenoates 6. Trapping of 6 with BuI resulted in high-yield formation of selenocarbonimidates 4. When alk-2-yn-1-ols 9 were allowed to react with selenium and isocyanides under similar conditions, new selenium-containing heterocycles 10, 2-imino-4-alkylidene-1,3-oxaselenolanes, were obtained via cycloaddition of oxyimidoylselenoates 13 generated in situ by intramolecular addition of selenolates to carbon-carbon triple bonds.