Synthesis of unprotected glyco-alkynones via molybdenum-catalyzed carbonylative Sonogashira cross-coupling reaction.

Herein we report a novel Mo-catalyzed carbonylative Sonogashira cross-coupling between 2-iodoglycals and terminal alkynes. The reaction displays major improvements compared to a related Pd-catalyzed procedure previously published by our group, such as utilizing unprotected sugar derivatives as starting materials and tolerance to substrates bearing chelating groups. In this work we also demonstrate the utility of the glyco-alkynone products as platform for further functionalization by synthesizing glyco-flavones via Au-catalyzed 6-endo-dig cyclization.

Synthesis of unprotected glyco-alkynones via molybdenum-catalyzed carbonylative Sonogashira cross-coupling reaction

Herein we report a novel Mo-catalyzed carbonylative Sonogashira cross-coupling between 2-iodoglycals and terminal alkynes. The reaction displays major improvements compared to a related Pd-catalyzed procedure previously published by our group, such as utilizing unprotected sugar derivatives as starting materials and tolerance to substrates bearing chelating groups. In this work we also demonstrate the utility of the glyco-alkynone products as platform for further functionalization by synthesizing glyco-flavones via Au-catalyzed 6-endo-dig cyclization.

Novel 2-Aryloxazoline Compounds Exhibit an Inhibitory Effect on Candida spp., Including Antifungal-Resistant Isolates.

Because of the increased resistance to currently available antifungals, fungal infections represent a significant challenge to human health. Herein, we report the synthesis of 2-aryloxazoline derivatives from the reaction between l-threonine and derivatives of salicylic or naphthoic acid. In total, 26 compounds were obtained and tested against species of Candida, Cryptococcus, and Aspergillus. We found that all of the compounds inhibited the growth of Candida species at low concentrations (<0.25 µg/mL) and exhibited reduced hemolytic and cytotoxic activities. Additionally, compounds 4i and 9i were especially effective against antifungal-resistant isolates and the emerging fungus Candida auris. However, the compounds were less active on Cryptococcus and Aspergillus. Because of the improved in vitro antifungal efficacy and attenuated cytotoxicity, these two 2-aryloxazolines obtained from salicylic and naphthoic acid derivatives, respectively, may be considered lead molecules for the development of novel antifungal drugs.

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.

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.

Carbonylative negishi-type coupling of 2-Iodoglycals with alkyl and aryl halides

C-Glycosides are valuable organic compounds in the field of medicinal chemistry due to their ubiquity inside living systems and pronounced biological activity. Herein, we describe an approach to alkyl-ketones bearing glycal units via the Pd-catalyzed carbonylative coupling of 2-iodoglycals and alkyl and aryl halides. Examples bearing a variety of functional groups are presented as well as a mechanistic proposal for this transformation.

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).

Carbonylative negishi-type coupling of 2-Iodoglycals with alkyl and aryl halides

C-Glycosides are valuable organic compounds in the field of medicinal chemistry due to their ubiquity inside living systems and pronounced biological activity. Herein, we describe an approach to alkyl-ketones bearing glycal units via the Pd-catalyzed carbonylative coupling of 2-iodoglycals and alkyl and aryl halides. Examples bearing a variety of functional groups are presented as well as a mechanistic proposal for this transformation.

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.

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.