Chiral biscinchona alkaloid promoted asymmetric allylic alkylation of 3-substituted benzofuran-2(3H)-ones with Morita-Baylis-Hillman carbonates

A highly diastereo- and enantioselective asymmetric allylic alkylation reaction with respect to prochiral 3-substituted benzofuran-2(3H)-ones and MBH carbonate by a chiral biscinchona alkaloid catalyst was investigated. The corresponding adducts, containing a quaternary center at the C3-position of the benzofuran-2(3H)-one as well as a vicinal tertiary center, were generally obtained in high yields (up to 97%) with very good diastereo- (up to 98:2 dr) and enantioselectivities (up to 95% ee).     

Organocatalytic asymmetric allylic alkylation of sulfonylimidates with Morita-Baylis-Hillman carbonates

The asymmetric allylic alkylation reaction of sulfonylimidates with various Morita-Baylis-Hillman (MBH) carbonates was accomplished by the catalysis of commercially available cinchona alkaloids catalyst (DHQD)2AQN.The corresponding allylic alkylation products were obtained in good yields with high stereoselectivities (up to 99% ee,89:11 dr).     

Highly enantioselective allylic alkylation of 5H-oxazol-4-ones with Morita-Baylis-Hillman carbonates

An organocatalytic enantioselective allylic alkylation of 5H-oxazol-4-ones with Morita-Baylis-Hillman carbonates has been developed. With 10?mol% of commercially available cinchonidine, a wide range of substituted 5H-oxazol-4-one derivatives were constructed in good-to-excellent yields with high diastereo- and enantioselectivities. The allylic alkylation adducts obtained are valuable precursors for the synthesis of chiral α-alkyl α-hydroxycarboxylic acid derivatives, which represent a series of versatile building blocks in many biologically active compounds.     

Chiral amine thiourea-promoted enantioselective Michael addition reactions of 3-substituted benzofuran-2(3H)-ones to maleimides

A highly diastereo- and enantioselective Michael addition reaction with respect to prochiral 3-substituted benzofuran-2(3H)-ones and maleimides by a chiral bifunctional thiourea-tertiary amine catalyst was investigated. The corresponding adducts, containing a quaternary center at the C3-position of the benzofuran-2(3H)-one as well as a vicinal tertiary center, were generally obtained in high yields (up to 99%) with very good diastereo- (up to >20:1 dr) and enantioselectivities (up to 97% ee).     

Room temperature asymmetric allylic trifluoromethylation of Morita-Baylis-Hillman carbonates

(DHQD)(2)PHAL-catalyzed asymmetric allylic trifluoromethylation of Morita-Baylis-Hillman adducts using a Rupert-Prakash reagent is reported. This transformation provided the S(N)2' trifluoromethylated products with good yields and excellent enantioselectivities at room temperature. It was also found that the reaction could be accelerated using acetonitrile as cosolvent.     

Chiral iminophosphoranes organocatalyzed asymmetric hydroxylation of 3-substituted oxindoles with oxaziridines

Enantioselective hydroxylation of N-protected 3-substituted oxindoles has been developed via chiral iminophosphorane catalysis with oxaziridines as oxidants. As such, a variety of optically active 3-substituted-3-hydroxy-2-oxindoles were obtained in excellent yields (91–99%) and moderate to excellent level of enantiomeric excess (up to 94% ee).     

Palladium-catalyzed regio- and enantioselective allylic alkylation of bis allylic carbonates derived from Morita-Baylis-Hillman adducts

Morita-Baylis-Hillman diene adducts are used as substrates in the palladium-catalyzed asymmetric allylic alkylation reaction with oxygen and carbon nucleophiles in good regio- and enantioselectivity.     

Ruthenium complex-catalyzed allylic alkylation of carbonucleophiles with allylic carbonates

Allylic carbonates except for allyl methyl carbonate reacted with carbonucleophiles such as ethyl acetoacetate in the presence of a catalytic amount of Ru(cod)(cot) [cod = cycloocta-1,5-diene, COT = cycloocta-1,3,5-triene] in N-methylpiperidine at 80°C to give the corresponding monoallylated carbonucleophiles in high yields with high regioselectivity. The regioselectivity was quite different from that in the palladium-catalyzed reactions. The allylation of carbonucleophiles using allyl methyl carbonate selectively gave the diallylated carbonucleophiles in high yields.     

Enantioselective organocatalytic asymmetric allylic alkylation. Bis(phenylsulfonyl)methane addition to MBH carbonates

The highly enantioselective asymmetric allylic alkylation of Morita-Baylis-Hillman carbonates with bis(phenylsulfonyl)methane is presented. The reaction is simply catalyzed by cinchona alkaloid derivatives affording the final alkylated products in good yields and enantioselectivities.     

Asymmetric Michael addition reactions of 3-substituted benzofuran-2(3H)-ones to nitroolefins catalyzed by a bifunctional tertiary-amine thiourea

The current work reports an organocatalytic strategy for the asymmetric catalysis of chiral benzofuran-2(3H)-ones bearing 3-position all-carbon quaternary stereocenters. Accordingly, highly enantioselective Michael addition reactions of 3-substituted benzofuran-2(3H)-ones to nitroolefins have been developed by utilizing a bifunctional tertiary-amine thiourea catalyst. The reactions accommodate a number of nitroolefins and 3-substituted benzofuran-2(3H)-ones to give the desired chiral benzofuran-2(3H)-one products with moderate to excellent yields (up to 98%) and moderate to very good selectivities (up to 19?:?1 dr and up to 91% ee). Theoretical calculations using the DFT method on the origin of the stereoselectivity were conducted. The effect of the nitroolefin substituent position on the stereoselectivity of the Michael addition reaction was also theoretically rationalized.     

Chiral calcium VAPOL phosphate mediated asymmetric chlorination and Michael reactions of 3-substituted oxindoles

We disclose a novel high yielding and highly enantioselective chiral calcium VAPOL phosphate-catalyzed chlorination of 3-substituted oxindoles with N-chlorosuccinimide (NCS). The reaction conditions are also shown to be effective for the catalytic enantioselective Michael addition of 3-aryloxindoles to methyl vinyl ketone.     

Catalytic asymmetric sulfenylation of unprotected 3-substituted oxindoles

Catalytic asymmetric sulfenylation of unprotected 3-substituted oxindoles has been developed via cooperative catalysis of a chiral N,N'-dioxide-Sc(OTf)(3) complex and a Br?nsted base. Utilizing readily available N-(phenylthio)phthalimide as the sulfur source, a wide range of optically active 3-phenylthiooxindoles were obtained in excellent yields with excellent enantioselectivities under mild reaction conditions.     

Chiral phosphine-catalyzed enantioselective construction of gamma-butenolides through substitution of Morita-Baylis-Hillman acetates with 2-trimethylsilyloxy furan

Chiral multifunctional phosphine (R)-N-(2'-diphenylphosphanyl-[1,1']binaphthalenyl-2-yl)methanesulfonamide L2 or (R)-N-(2'-diphenylphosphanyl-[1,1']binaphthalenyl-2-yl)acetamide L3 is an efficient catalyst in the allylic substitutions of MBH acetates 1 with 2-trimethylsilyloxy furan 2 to provide gamma-butenolides 3 in good to excellent yields and enantiomeric excesses in the presence of water.     

Ruthenium(II) complexes with 2-methyl-3-substituted (3H)-quinazolin-4-ones

A number of ruthenium(II) complexes of some polydentate ON, OO and ONO donors in the form of 2-methyl-3-substituted (3H)-quinazolin-4-ones have been synthesized and studied. The reaction between RuCl₂(DMSO)₄ and the uninegative bidentate ligands yielded complexes of the type Ru(DMSO)₂(OO)₂ (OO = MHQ, PHQ, MHEQ, MHPQ or MCMQ), displacing only two DMSO groups along with chlorides, whereas the neutral bidentate ligands gave RuCl₂(ON)₂ (ON = MAQ, PAQ, MANQ, PANQ, MAAQ, MAPQ, MPQ or PPQ), displacing all the DMSO groups. A uninegative terdentate ligand (MHAQ) with ONO donors, however, yielded a bis chelate of ruthenium(II).     

Azo coupling of 5-substituted furan-2(3H)-ones and 1H-pyrrol-2(3H)-ones with arene(hetarene)diazonium salts

5-Substituted furan-2(3H)-ones and 1-phenyl-1H-pyrrol-2(3H)-ones reacted with diazonium salts derived from substituted anilines and 1H-1,2,4-triazol-5-amine to give azo coupling products at the methylene group in the heteroring. The products were found to exist as hydrazone tautomers.     

Improved Method for Preparation of 3-(1H-Indol-3-yl)benzofuran-2(3H)-ones

3-(1H-Indol-3-yl)benzofuran-2(3H)-ones were efficiently accessed via polyphosphoric acid-mediated condensation of 3-(2-nitrovinyl)-1H-indoles with phenols.     

Preparation and alkylation of regioisomeric tetrahydrophthalimide-substituted indolin-2(3H)-ones

A series of novel regioisomeric tetrahydrophthalimide-substituted indolin-2-ones has been prepared via the Sommelet-Hauser type cyclization of appropriately substituted anilines as potential herbicides. The resultant indolin-2-ones were then regioselectively alkylated at N-1 and C-3 to give 1,3,3-trisubstituted indolin-2-ones. The most active series was also prepared by the bis-nitration of m-fluorophenylacetic acid followed by reduction and cyclization to give 6-amino-5-fluoroindolin-2-one. Elaboration to the tetrahydrophthalimide-substituted indolin-2-one was followed by C- and N-alkylation to give the desired compounds.     

Lewis base catalyzed enantioselective allylic hydroxylation of Morita-Baylis-Hillman carbonates with water

A Lewis base catalyzed allylic hydroxylation of Morita-Baylis-Hillman (MBH) carbonates has been developed. Various chiral MBH alcohols can be synthesized in high yields (up to 99%) and excellent enantioselectivities (up to 94% ee). This is the first report using water as a nucleophile in asymmetric organocatalysis. The nucleophilic role of water has been verified using (18)O-labeling experiments.     

Highly regio- and diastereoselective construction of spirocyclopenteneoxindoles through phosphine-catalyzed [3 + 2] annulation of Morita-Baylis-Hillman carbonates with isatylidene malononitriles

Phosphine-catalyzed highly regio- and diastereoselective [3 + 2] annulation of Morita-Baylis-Hillman (MBH) carbonates with isatylidene malononitriles has been disclosed to give the corresponding spirocyclopenteneoxindoles in excellent yields under mild conditions. A plausible reaction mechanism has also been proposed on the basis of previous literature.