Stereo- and regioselective cu-catalyzed hydroboration of alkynyl chalcogenoethers

A mild stereo- and regioselective Cu-catalyzed hydroboration method for the synthesis of (Z)-seleno-alkenyl boronates and (Z)-thio-alkenylboronates from internal alkynes in the presence of commercially available B2pin2 is presented. This highly selective transformation relies on the use of N-heterocyclic carbene (NHC) complex IPrCuCl as the active catalytic species. We also explore the functionalization of the alkenylboronates obtained via oxidation to give a -chalcogeno ketones, useful building blocks for the synthesis of more complex chalcogen-containing molecules.

Palladium-catalyzed thio- and selenocarbonylation of 2-iodoglycals

The carbonylative cross-coupling reactions of 2-iodoglycals with thiols and selenols in the presence of molybdenum hexacarbonyl as a solid source of carbon monoxide is described. This methodology permitted the synthesis of 29 C2-glycosides bearing thioester and selenoester functionalities in moderate to excellent yields and high functional group tolerance. Moreover, this communication describes the first catalytic carbonylative coupling reaction of selenols with a carbon electrophile.

Stereo- and regioselective cu-catalyzed hydroboration of alkynyl chalcogenoethers

A mild stereo- and regioselective Cu-catalyzed hydroboration method for the synthesis of (Z)-seleno-alkenyl boronates and (Z)-thio-alkenylboronates from internal alkynes in the presence of commercially available B2pin2 is presented. This highly selective transformation relies on the use of N-heterocyclic carbene (NHC) complex IPrCuCl as the active catalytic species. We also explore the functionalization of the alkenylboronates obtained via oxidation to give a -chalcogeno ketones, useful building blocks for the synthesis of more complex chalcogen-containing molecules.

Palladium-catalyzed thio- and selenocarbonylation of 2-iodoglycals

The carbonylative cross-coupling reactions of 2-iodoglycals with thiols and selenols in the presence of molybdenum hexacarbonyl as a solid source of carbon monoxide is described. This methodology permitted the synthesis of 29 C2-glycosides bearing thioester and selenoester functionalities in moderate to excellent yields and high functional group tolerance. Moreover, this communication describes the first catalytic carbonylative coupling reaction of selenols with a carbon electrophile.

Iron (III)-promoted synthesis of substituted 4H-Chalcogenochromenes and chemoselective functionalization

The iron(III)-promoted synthesis of densely-substituted 4H-chalcogenchromene from organochalcogen propargylamines in the presence of diaryl dichalcogenides is reported. Subsequent C2-functionalization with electrophiles and potassium trifluoroborate salts via Suzuki-Miyaura coupling reaction are also presented. A plausible mechanism based on HRMS experiments is proposed and discussed.

Synthesis of d-glyco-alkynone derivatives via carbonylative Sonogashira reaction

A carbonylative Sonogashira coupling approach to the synthesis of glyco-alkynones is described. Eighteen examples were obtained in moderate do nearly quantitative yields under mild conditions employing Mo(CO)6 as a safe carbon monoxide source. Functionalization of the alkynyl moiety via cycloaddition with organic azides provided six examples of glyco-triazoles.

Synthesis of amidoglucals and glucal esters via carbonylative coupling reactions of 2-iodoglucal using Mo(CO)6 as a CO source

The synthesis of amidoglucals and glucal esters in good to high yields using 2-iodo-3,4,6-tri-O-acetyl-d-glucal as a substrate, Mo(CO)(6) as a carbon monoxide source and PdCl2 as a catalyst is reported. This procedure shows advantages when compared to other published methodologies, as it is carried out in one pot relying on short reaction times at mild temperatures, under ligand-free conditions and with only one equivalent of Mo(CO)(6).

Iron (III)-promoted synthesis of substituted 4H-Chalcogenochromenes and chemoselective functionalization

The iron(III)-promoted synthesis of densely-substituted 4H-chalcogenchromene from organochalcogen propargylamines in the presence of diaryl dichalcogenides is reported. Subsequent C2-functionalization with electrophiles and potassium trifluoroborate salts via Suzuki-Miyaura coupling reaction are also presented. A plausible mechanism based on HRMS experiments is proposed and discussed.

Synthesis of d-glyco-alkynone derivatives via carbonylative Sonogashira reaction

A carbonylative Sonogashira coupling approach to the synthesis of glyco-alkynones is described. Eighteen examples were obtained in moderate do nearly quantitative yields under mild conditions employing Mo(CO)6 as a safe carbon monoxide source. Functionalization of the alkynyl moiety via cycloaddition with organic azides provided six examples of glyco-triazoles.

Synthesis of amidoglucals and glucal esters via carbonylative coupling reactions of 2-iodoglucal using Mo(CO)6 as a CO source

The synthesis of amidoglucals and glucal esters in good to high yields using 2-iodo-3,4,6-tri-O-acetyl-d-glucal as a substrate, Mo(CO)(6) as a carbon monoxide source and PdCl2 as a catalyst is reported. This procedure shows advantages when compared to other published methodologies, as it is carried out in one pot relying on short reaction times at mild temperatures, under ligand-free conditions and with only one equivalent of Mo(CO)(6).

Ytterbium-catalyzed formal [4+2] cycloaddition: synthesis of chalcogen-quinolines 3-unsubstituted

A regioselective ytterbium-catalyzed annulation reaction between ethylglyoxalate, anilines and silyl-alkynes bearing selenyl- and telluryl-moieties for the formation of poly-substituted quinolones is described. A series of examples formed under mild conditions are presented, including a scaled-up reaction and a study on catalyst recyclability.

Copper(I)/succinic acid cooperatively catalyzed one-pot synthesis of organoselenium-propargylamines via A3-coupling

Selenium propargylamines were synthesized via an A(3)-coupling approach using piperidine, p-methoxybenzaldehyde, and trimethylsilyl selenium-acetylene, catalyzed by copper(i) chloride and succinic acid as an additive, in good to excellent yields. This method is advantageous in that desilylation of the trimethylsilyl selenium-acetylene occurs in situ. The reaction time was monitored by FTIR studies and a probable mechanism is described. Scale-up was also performed in satisfactory yield. These selenium propargylamines could be hydrohalogenated to synthesize halovinyl selenides. The stereochemistry was determined by treatment with n-butyllithium and the coupling constant (J) values in H-1 NMR spectra. The vinyl selenides were employed in Sonogashira cross-coupling reactions to produce the corresponding enynes, with yields ranging from moderate to good.

Ytterbium-catalyzed formal [4+2] cycloaddition: synthesis of chalcogen-quinolines 3-unsubstituted

A regioselective ytterbium-catalyzed annulation reaction between ethylglyoxalate, anilines and silyl-alkynes bearing selenyl- and telluryl-moieties for the formation of poly-substituted quinolones is described. A series of examples formed under mild conditions are presented, including a scaled-up reaction and a study on catalyst recyclability.

Copper(I)/succinic acid cooperatively catalyzed one-pot synthesis of organoselenium-propargylamines via A3-coupling

Selenium propargylamines were synthesized via an A(3)-coupling approach using piperidine, p-methoxybenzaldehyde, and trimethylsilyl selenium-acetylene, catalyzed by copper(i) chloride and succinic acid as an additive, in good to excellent yields. This method is advantageous in that desilylation of the trimethylsilyl selenium-acetylene occurs in situ. The reaction time was monitored by FTIR studies and a probable mechanism is described. Scale-up was also performed in satisfactory yield. These selenium propargylamines could be hydrohalogenated to synthesize halovinyl selenides. The stereochemistry was determined by treatment with n-butyllithium and the coupling constant (J) values in H-1 NMR spectra. The vinyl selenides were employed in Sonogashira cross-coupling reactions to produce the corresponding enynes, with yields ranging from moderate to good.