Enantioselective α-Amination of Amides by One-Pot Organo-/Iodine Sequential Catalysis.

An one-pot organo- and iodine sequential catalysis strategy for reactions of amides with pyrazole-based primary amines was described to synthesize chiral α-amino amides with a quaternary stereocenter. This methodology exhibited strong asymmetric induction, resulting in a typical enantiomeric excess value exceeding 99% and diastereoselectivity up to >99:1 dr. Moreover, the reaction was conducted without the use of any metals or strong bases.

Enantioselective Syntheses of C2-Symmetric Pyrazolones and Diones via One-Pot Organo-/Iodine Sequential Catalysis.

The catalytic diastereo- and enantioselective syntheses of C2-symmetric axially chiral 1,4-dicarbonyl derivatives with 2,3-quaternary stereocenters were achieved by utilizing an organo-/iodine binary catalytic strategy. The reactions proceeded well under mild conditions without metals or strong bases.

In situ generation of highly reactive allenes from nitrocyclopropanes: controllable synthesis of enynes and enesters.

A new and efficient strategy for ring-opening reactions of nitrocyclopropanes is developed for the first time for the divergent synthesis of enynes and enesters via in situ generated highly reactive electron-deficient intermediate allenes. Controllable approaches resulted in enynes and enesters with up to 89% and 90% yields, respectively. The reaction features easy operation, involves green solvents and simple inorganic bases, and is transition-metal free.

Direct N-alkylation of sulfur-containing amines.

An efficient ruthenium-catalyzed method has been developed for the direct N-alkylation of sulfur-containing amines with alcohols, for the first time, by a step-economical and environmentally friendly hydrogen borrowing strategy. The present methodology features base-free conditions and broad substrate scope, with water being the only by-product. Moreover, this protocol has been applied to the synthesis of the pharmaceutical drug Quetiapine.

Merging catalyst-free synthesis and iodine catalysis: one-pot synthesis of dihydrofuropyrimidines and spirodihydrofuropyrimidine pyrazolones.

A new and efficient one-pot strategy combining catalyst-free synthesis and iodine catalysis has been developed for the synthesis of dihydrofuropyrimidines and spirodihydrofuropyrimidine pyrazolones. This approach affords products in moderate to high yields (up to 96%) with excellent diastereoselectivities (up to >25 : 1 dr). The reaction is simple to carry out and is metal-free.

Combining Organocatalysis and Iodine Catalysis: One-Pot Sequential Catalytic Synthesis of Chiral Spirodihydrobenzofuran Pyrazolones and Spirodihydrobenzofuran Oxindoles.

A new and efficient catalytic strategy that combines asymmetric organocatalysis and iodine catalysis was first developed for the one-pot Michael/iodization/SN2 nucleophilic substitution sequential catalytic synthesis of spirodihydrobenzofuran pyrazolones and spirodihydrobenzofuran oxindoles. The approach results in products with moderate to high yields (up to 93%), high to excellent enantioselectivities (up to 99% ee), and excellent diastereoselectivities (up to >99:1 dr). The reaction features simple operation and is metal-free and base-free.

Asymmetric synthesis of polysubstituted chiral chromans via an organocatalytic oxa-Michael-nitro-Michael domino reaction.

A catalytic asymmetric method for the synthesis of polysubstituted chromans via an oxa-Michael-nitro-Michael reaction has been developed. The squaramide-catalyzed domino reaction of 2-hydroxynitrostyrenes with trans-ß-nitroolefins produced chiral chromans with excellent enantioselectivities (up to 99% ee), diastereoselectivities (up to >20 : 1 dr), and moderate to good yields (up to 82%).

One-pot asymmetric synthesis of a spiro[dihydrofurocoumarin/pyrazolone] scaffold by a Michael addition/I2-mediated cyclization sequence.

An asymmetric formal one-pot reaction of 4-hydroxycoumarins with unsaturated pyrazolones has been developed by merging a chiral bifunctional organocatalyst with molecular iodine, which furnished a series of optically active spiro[dihydrofurocoumarin/pyrazolone] heterocycles with spiro quaternary stereogenic centers in moderate to excellent yields (up to 99%) with excellent diastereoselectivities (up to >99 : 1 dr) and good to excellent enantioselectivities (up to 99% ee). The application in the gram-scale synthesis of chiral spiro[dihydrofurocoumarin/pyrazolone] compounds was also successfully realized.

Tryptophan/copper-catalyzed aromatization reaction of chiral cyclohexanones to phenols.

By merging organocatalysis with copper catalysis, a highly efficient stereospecific approach for the synthesis of chiral phenols from cyclohexanones has been developed for the first time. The aromatization reaction proceeds through the in situ formation of enone intermediates and further subsequent bromination/dehydrobromination reactions. And a series of functionalized phenol derivatives are obtained in good yields (up to 89%) and good to excellent enantioselectivities (up to 99% ee).

Jørgensen-Hayashi catalysts supported on poly(ethylene glycol)s as highly efficient and reusable organocatalysts for the enamine-catalyzed asymmetric Michael reaction.

A new kind of recyclable and reusable PEG-supported Jørgensen-Hayashi catalyst is synthesized for the first time and proven to be efficient for the enamine-catalyzed asymmetric Michael reaction with generally moderate to good diastereoselectivity and high to excellent enantioselectivity (up to 6 : 1 dr, 99% ee). The prepared PEG-supported catalyst can be recovered eight times and was found to provide similar diastereoselectivity and enantioselectivity to unsupported functional catalysts.

2-[1-(4-Bromo-phen-yl)-2-nitro-eth-yl]hexa-noic acid.

In the crystal structure of the title compoud, C14H18BrNO4, mol-ecules are linked by a strong O-H⋯O hydrogen bond and weaker C-H⋯O inter-actions. The benzene ring makes dihedral angles of 3.67 (3) and 72.63 (3)° with the carb-oxy-lic acid group and the nitro group, respectively.

Pd(OAc)2-catalyzed regioselective aromatic C-H bond fluorination.

A novel Pd(OAc)2-NFSI-TFA system was developed for the highly selective ortho-monofluorination directed by diverse aryl-N-heterocyclic directing groups e.g., quinoxaline, pyrazole, benzo[d]oxazole, and pyrazine derivatives. A Pd(II/IV) catalytic cycle was proposed based on the ESI-MS/MS studies.

(4aR,9R,9aR)-7-Bromo-9-nitro-methyl-2,3,4,4a,9,9a-hexa-hydro-1H-xanthen-1-one.

The title compound, C14H14BrNO4, contains a tricyclic ring system including three contiguous stereocenters all of which exhibit an R configuration. The cyclo-hexa-none ring adopts a chair conformation. The central oxane ring assumes a strained envelope conformation, with five of the ring atoms being nearly coplanar with the bromo-phenyl group and with the C atom adjacent to the O atom and fused with the cyclo-hexa-none ring as the flap. In the crystal, mol-ecules are linked into a three-dimensional network by C-H⋯O inter-actions.

(2S,4R)-2-[(1R)-1-(4-Bromo-phen-yl)-2-nitro-eth-yl]-4-ethyl-cyclo-hexa-none.

The crystal structure of the title compound, C(16)H(20)BrNO(3), contains three chiral centers in the configuration 1R,2S,6R. The cyclo-hexane ring is in a chair conformation. In the crystal, mol-ecules are linked by weak C-H⋯O inter-actions, forming chains along the a-axis direction.

Prolinethiol ether catalysis in an asymmetric Michael reaction: solvent-free synthesis of functionalized monohaloalkenes.

The organocatalytic Michael reaction of ketones with γ-monohalonitrodienes catalyzed by chiral prolinethiol ether under solvent-free conditions was developed. The described method represents a novel approach for accessing highly functionalized monohaloalkenes with α, ß-stereocenters of up to >99% ee.

(2S,4S)-2-[(S,E)-2-Bromo-1-nitro-methyl-3-phenyl-all-yl]-4-methyl-cyclo-hexa-none.

The crystal structure of the title compoud, C(17)H(20)BrNO(3), contains three chiral centers, which all exhibit an S configuration. The C=C double bond has an E conformation. The cyclo-hexane ring is in a chair conformation. In the crystal, mol-ecules are linked by weak N-O⋯Br inter-actions [O⋯Br = 3.136 (4) Å].

(S)-2-[(S,Z)-3-Bromo-1-nitro-4-phenyl-but-3-en-2-yl]cyclo-hexa-none.

In the crystal structure of the title compound, C(16)H(18)BrNO(3), the two stereogenic centres both have an S configuration. The cyclo-hexyl ring adopts a chair conformation. In the crystal, mol-ecules are linked by weak N-O⋯Br contacts [O⋯Br = 3.289 (4) Å].

The highly enantioselective Michael addition of ketones to nitrodienes catalyzed by the efficient organocatalyst system of pyrrolidinyl-thioimidazole and chiral thioureido acid.

The highly enantioselective Michael addition reaction of ketones to nitrodienes was promoted efficiently by the accessible and fine-tunable organocatalytic system of pyrrolidinyl-thioimidazole and chiral thioureido acid. The corresponding adducts were afforded in good yields with high diastereoselectivities (up to 99 : 1) and excellent enantioselectivities (up to 99% ee).