Bifunctional Thiourea-tertiary Amine Research Articles

Asymmetric Construction of Spiro[thiopyranoindole-benzoisothiazole] Scaffold via a Formal [3 + 3] Spiroannulation.

An enantioselective formal thio[3 + 3] spiroannulation reaction of indoline-2-thiones to 1-azadienes has been developed by the use of a quinine-derived bifunctional tertiary amine-thiourea catalyst, which furnished a series of optically active spiro[thiopyranoindole-benzoisothiazole] heterocycles with a spiro quaternary C-N/C-S stereogenic centers in high yields with good to excellent diastereo- and enantioselectivities.

Theoretical studies on the activation mechanism involving bifunctional tertiary amine–thioureas and isatylidene malononitriles

DFT studies on the activation mechanism of the Michael addition reactions containing bifunctional tertiary amine–thioureas and isatylidene malononitriles have been performed at the B3LYP/6-311++G(d,p)//B3LYP/6-31G(d) level of theory.

ChemInform Abstract: Organocatalytic Asymmetric Friedel—Crafts Reaction of 1‐Naphthols with Isatins: An Enantioselective Synthesis of 3‐Aryl‐3‐hydroxy‐2‐oxindoles.

Abstract An organocatalytic enantioselective Friedel–Crafts reaction of 1-naphthols with isatins has been developed employing bifunctional thiourea–tertiary amine organocatalysts. A variety of isatin derivatives react well with 1-naphthols in the presence of Cinchona derived thiourea 1a to provide biologically important chiral 3-aryl-3-hydroxy-2-oxindoles ( 3a – zg ) in good yield (70–84%) and moderate to good enantioselectivity (37–83%).

ChemInform Abstract: Asymmetric Organocatalytic Conjugate Addition of Dialkyl Phosphites to N‐Unprotected Isatylidene Malononitriles: Access to 3‐Phospho‐2‐oxindoles with Chiral Quaternary Stereocenters.

Abstract The enantioselective Michael addition of dialkyl phosphites to N-unprotected isatylidene malononitriles has been established for the first time by using a simple bifunctional tertiary amine–thiourea catalyst. The corresponding adducts, 3-phospho-2-oxindoles, containing a chiral quaternary carbon center at the 3-position of the oxindole, were obtained in good to excellent yields (up to 98%) with moderate to excellent enantioselectivities (up to 95% ee). In addition, optically active 3,3′-disubstituted oxindoles bearing carboxylate and phosphonate groups were facilely obtained by the oxidative degradation of the Michael adducts.

Cinchona-derived thiourea catalyzed hydrophosphonylation of ketimines—an enantioselective synthesis of α-amino phosphonates

A highly enantioselective addition of diphenyl phosphite to ketimines derived from isatins has been developed employing bifunctional thiourea-tertiary amine organocatalysts. A variety of isatins derived ketimines react well with diphenyl phosphite in the presence of Cinchona-derived thiourea (epiCDT) to provide biologically important chiral 3-substituted 3-amino-2-oxindoles (3a–l) in good yield (up to 88%) and good enantioselectivity (up to 97% ee). The three-component version of the reaction through a domino aza-Wittig/phospha-Mannich sequence has successfully been explored.

ChemInform Abstract: Enantioselective Organocatalytic Multicomponent Synthesis of 2,6‐Diazabicyclo[2.2.2]octanones.

The title reaction of β-ketoamides, acrolein, and aminophenols, catalyzed by a bifunctional thiourea-tertiary amine organocatalyst, enables the preparation of an enantioenriched diazabicyclo[2.2.2]octanone (2,6-DABCO) scaffold. The chemoselective reaction sequence installs five new bonds and three stereocenters, two of which are contiguous tetrasubstituted centers, with excellent yields and high levels of stereocontrol. M.S.=molecular sieves

New class of bifunctional thioureas from l-proline: highly enantioselective Michael addition of 1,3-dicarbonyls to nitroolefins

A new class of bifunctional tertiary amine thiourea was synthesized from l-proline. The reported thiourea is amenable to steric and electronic modifications at the stereogenic center bearing a thiourea moiety. Excellent enantioselectivity was obtained in the Michael addition of 2,4-pentanedione to various nitro olefins using the new organocatalyst. The construction of contiguous stereocenters via the Michael reaction of substituted 1,3-dicarbonyls to nitro olefins was also carried out with very good yield, enantioselectivity, and diastereoselectivity.

Organocatalytic Asymmetric Friedel–Crafts Reaction of Sesamol with Isatins: Access to Biologically Relevant 3‐Aryl‐3‐hydroxy‐2‐oxindoles

The Friedel-Crafts reaction of electron-rich phenols with isatins was developed by employing bifunctional thiourea-tertiary amine organocatalysts. Cinchona alkaloid derived thiourea epiCDT-3 a efficiently catalyzed the Friedel-Crafts-type addition of phenols to isatin derivatives to provide 3-aryl-3-hydroxy-2-oxindoles 7 and 9 in good yield (80-95 %) with good enantiomeric excess (83-94 %). Friedel-Crafts adduct 7 t was subjected to a copper(I)-catalyzed azide-alkyne cycloaddition to obtain biologically important 3-aryl-3-hydroxy-2-oxindole 11 in good enantiomeric excess and having a 1,2,3-triazole moiety.

Organocatalytic asymmetric Friedel–Crafts reaction of 1-naphthols with isatins: an enantioselective synthesis of 3-aryl-3-hydroxy-2-oxindoles

An organocatalytic enantioselective Friedel–Crafts reaction of 1-naphthols with isatins has been developed employing bifunctional thiourea–tertiary amine organocatalysts. A variety of isatin derivatives react well with 1-naphthols in the presence of Cinchona derived thiourea 1a to provide biologically important chiral 3-aryl-3-hydroxy-2-oxindoles (3a–zg) in good yield (70–84%) and moderate to good enantioselectivity (37–83%).

Asymmetric organocatalytic conjugate addition of dialkyl phosphites to N-unprotected isatylidene malononitriles: access to 3-phospho-2-oxindoles with chiral quaternary stereocenters

The enantioselective Michael addition of dialkyl phosphites to N-unprotected isatylidene malononitriles has been established for the first time by using a simple bifunctional tertiary amine–thiourea catalyst. The corresponding adducts, 3-phospho-2-oxindoles, containing a chiral quaternary carbon center at the 3-position of the oxindole, were obtained in good to excellent yields (up to 98%) with moderate to excellent enantioselectivities (up to 95% ee). In addition, optically active 3,3′-disubstituted oxindoles bearing carboxylate and phosphonate groups were facilely obtained by the oxidative degradation of the Michael adducts.

Organocatalytic enantioselective tandem Michael addition-oxidation of 3-substituted oxindoles with 1,4-benzoquinone

By employing a chiral bifunctional thiourea-tertiary amine as catalyst, enantioselective tandem Michael addition-oxidation of 3-monosubstituted oxindoles with 1,4-benzoquinones were realized. The reactions afforded a wide range of 3,3-disubstituted oxindoles with moderate to good yields (up to 87%) in moderate to good enantioselectivities (up to 96%).

Highly enantioselective Michael addition of diethyl malonate to chalcones catalyzed by cinchona alkaloids-derivatived bifunctional tertiary amine-thioureas bearing multiple hydrogen-bonding donors

Chalcones are still challenge substrates in Michael reactions, and only limited success has been achieved. This work describes a highly enantioselective Michael addition of diethyl malonate with chalcones catalyzed by cinchona alkaloids-derivatived bifunctional tertiary amine-thioureas bearing multiple hydrogen-bonding donors.

Enantioselective Organocatalytic Multicomponent Synthesis of 2,6‐Diazabicyclo[2.2.2]octanones

Three-star compounds: The title reaction of β-ketoamides, acrolein, and aminophenols, catalyzed by a bifunctional thiourea-tertiary amine organocatalyst, enables the preparation of an enantioenriched diazabicyclo[2.2.2]octanone (2,6-DABCO) scaffold. The chemoselective reaction sequence installs five new bonds and three stereocenters, two of which are contiguous tetrasubstituted centers, with excellent yields and high levels of stereocontrol. M.S.=molecular sieves.

Enantioselective Synthesis of Quaternary 3-Aminooxindoles via Organocatalytic Asymmetric Michael Addition of 3-Monosubstituted 3-Aminooxindoles to Nitroolefins

An enantioselective synthesis of quaternary 3-aminooxindoles with 3-monosubstituted 3-aminooxindoles as nucleophiles is first presented. A Michael addition reaction of 3-monosubstituted 3-aminooxindoles to nitroolefins has been developed with a bifunctional thiourea-tertiary amine as a catalyst to afford a range of 3,3-disubstituted oxindoles bearing adjacent quaternary-tertiary centers in good results (up to 98% yield, >99:1 dr, and 92% ee). We also demonstrate the potential synthetic utility of this methodology by a transformation of the product into a spirocyclic oxindole compound.

Highly efficient synthesis of spiro[oxazolidine-2-thione-oxindoles] with 3-isothiocyanato oxindoles and aldehydes via an organocatalytic cascade aldol-cyclization reaction

A highly efficient method for the construction of a family of spiro[oxazolidine-2-thione-oxindoles] with 3-isothiocyanato oxindoles and aldehydes via a cascade aldol-cyclization process has been developed. This method provides access to spiro[oxazolidine-2-thione-oxindole] derivatives bearing two vicinal quaternary/tertiary stereocenters in up to 95% yield, 98:2 dr, and 89% ee with a chiral bifunctional thiourea–tertiary amine organocatalyst based on DPEN scaffold. Good reactivity was observed and the reaction could be completed within 1.0 min.

Enantioselective conjugate addition of 3-fluoro-oxindoles to vinyl sulfone: an organocatalytic access to chiral 3-fluoro-3-substituted oxindoles

An organocatalytic conjugate addition of prochiral 3-fluorinated oxindoles to vinyl sulfones was described for the first time. In the presence of bifunctional tertiary amine-thiourea catalysts, 3-fluoro-3-substituted oxindole adducts were obtained in excellent yields and with high enantiomeric excesses.

ChemInform Abstract: Organocatalytic Enantioselective Michael Addition of a Kojic Acid Derivative to Nitro Olefins.

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ChemInform Abstract: Enantioselective Synthesis of Optically Active cis‐β‐Thio‐α‐amino Acid Derivatives Through an Organocatalytic Cascade Thio‐Michael/Ring Opening Process.

Non-naturally enantioenriched cis-β-thio-α-amino acid derivatives were synthesized through one pot, cascade thio-Michael/ring opening reaction of aromatic thiols with (Z)-olefinic azlactones in good yields with high levels of diastereoselectivities and enantioselectivities, which was catalyzed by a chiral bifunctional thiourea–tertiary amine catalyst.

Enantioselective Construction of 3-Hydroxy Oxindoles via Decarboxylative Addition of β-Ketoacids to Isatins

The first highly enantioselective decarboxylative addition of β-ketoacids to isatins mediated by a bifunctional tertiary amine-thiourea catalyst has been developed, allowing facile synthesis of biologically important 3-hydroxy oxindoles in good yields and excellent enantioselectivities. The method reported represents a valuable approach of utilizing β-ketoacids as synthetic equivalents of aryl/alkyl methyl ketone enolates.

ChemInform Abstract: Enantioselective Organocatalytic Oxyamination of Unprotected 3‐Substituted Oxindoles.

AbstractThe asymmetric α‐oxyamination of 3‐substituted oxindoles (I) and (IV) with nitrosobenzene (II) is readily catalyzed by a bifunctional tertiary amine—thiourea organocatalyst to give the corresponding 3‐aminooxindoles (III) and (V) in moderate enantioselectivities (23—72% e.e.).