Hongwen Hu

Synthesis of quinazolin-4(3H)-ones and 1,2-dihydroquinazolin-4(3H)-ones with the aid of a low-valent titanium reagent

Abstract A short and facile synthesis of a series of quinazolin-4(3H)-ones and 1,2-dihydroquinazolin-4(3H)-ones was accomplished in good yields via the novel reductive cyclization of o-nitrobenzamides and triethyl orthoformate, aldehydes or ketones promoted by TiCl4/Zn.

Cu-Catalyzed Cross-Dehydrogenative Coupling Reactions of (Benzo)thiazoles with Cyclic Ethers

Copper-catalyzed cross-dehydrogenative coupling (CDC) reactions of (benzo)thiazoles with cyclic ethers were developed under mild conditions. In particular, the formation of C-C bonds via the CDC reactions between non-benzo-fused azoles and ethers are reported for the first time. In addition, the acetals, known as the masked 2-thiazolecarboxaldehydes, could be successfully obtained by this CDC reaction. The preliminary mechanism and supportive DFT calculations are discussed as well.

Synthesis of chiral ligands derived from the Betti base and their use in the enantioselective addition of diethylzinc to aromatic aldehydes

Abstract A novel procedure for selective direct N , N -alkylation of the chiral Betti base was developed, and a new family of chiral ligands, ( S )-1-(α-cycloaminobenzyl)-2-naphthols, were prepared. The ligands with five- and six-membered cyclic amines showed highly efficient asymmetric induction in the addition of diethylzinc to aromatic aldehydes in 93–96% yields and 91–99% ee.

Organocatalytic oxa/aza-Michael–Michael Cascade Strategy for the Construction of Spiro [Chroman/Tetrahydroquinoline-3,3′-oxindole] Scaffolds

A new useful and effective chiral amine-catalyzed oxa- and aza-Michael-Michael cascade methodology for the construction of enantiomerically enriched indolinones spiro-fused with chromans or tetrahydroquinolines is reported. By employing suitable organocatalysts depending on the different Michael donors (Ar-OH/Ar-NHR), the processes offered excellent stereocontrol (dr >20:1, >99% ee) under mild conditions.

Palladium catalyzed reaction of α-chloromethylnaphthalene with olefins

Abstract The reaction of α-chloromethylnaphthalene with various olefins in the presence of palladium acetate produces three different kinds of products. The coupling products with the olefinic bond conjugated to the naphthalene ring are the major products for the reactions of most olefins. An unusual rearrangement product formed via a cyclopalladation intermediate is isolated from the reactions of the two N-vinyl olefins.

Novel preparation of non-racemic 1-[α-(1-azacycloalkyl)benzyl]-2-naphthols from Betti base and their application as chiral ligands in the asymmetric addition of diethylzinc to aryl aldehydes

A novel route for the preparation of non-racemic 1-[α-(1-azacycloalkyl)benzyl]-2-naphthols was developed, which involves regioselective N-cycloalkylation of the Betti base with dials in the presence of NaBH3CN to give 1-azacycloalka[2,1-b]oxazine followed by the selective cleavage of a C–O bond with LiAlH4. As a new family of chiral ligands, their application in the enantioselective addition of diethylzinc to aryl aldehydes was tested. The ligands incorporating pyrrolidine and piperidine led to highly efficient asymmetric induction to give products in up to 96% yield and 99% ee.

The Aromatization of Hantzsch 1,4-Dihydropyridines by Tetrakis-Pyridine Cobalt (II) Dichromate (TPCD)

Abstract Aromatization of Hantzsch 1,4-dihydropyridines (la-n) were promoted by tetrakis-pyridine cobalt (11) dichromate to yield corresponding pyridine derivatives (2a-n) in moderate to high yields (70-87%). The reaction was carried out under mild and convenient conditions.

Silver-Catalyzed Cascade Radical Cyclization: A Direct Approach to 3,4-Disubstituted Dihydroquinolin-2(1H)-ones through Activation of the P–H Bond and Functionalization of the C(sp2)–H Bond

A silver-catalyzed cascade cyclization of cinnamamides with diphenylphosphine oxide was developed, in which activation of the P-H bond and functionalization of the C(sp(2))-H bond occurred. A direct method for the synthesis of 3,4-disubstituted dihydroquinolin-2(1H)-ones was developed.

Synthesis and characterisation of alkyl-N,N′-bis(salicylidene)ethylenediamino- and alkyl-N,N′-bis(salicylidene)-1,2-phenylenediaminogallium or indium complexes: crystal structure of methyl-N,N′-bis(salicylidene)-1,2-phenylenediaminoindium

Abstract The reaction of trialkylgallium or indium R3M (M=In, Ga; R=Me, Et) with N,N′-ethylenebis(salicylideneimine) or 1,2-N,N′-phenylenebis(salicylideneimine) yields seven intramolecularly coordinated organogallium or organoindium complexes. Two hydroxyl protons in the ligands react with both trialkylindium and trimethylgallium, while one hydroxyl group reacts exclusively with triethylgallium. The complexes obtained have been fully characterised by elemental analysis, 1H-NMR, IR and mass spectroscopy. The structure of methyl-N,N′-bis(salicylidene)-1,2-phenylenediaminoindium (1) has been determined by single-crystal X-ray analysis. The In atom is five coordinate in the structure. Fluorescence spectroscopy has shown that the maximum emission wavelength of 1 is 499 nm upon radiation by UV light.

A facile synthesis of 1,2-dihydroquinazolin-4(3H)-ones with the aid of a low-valent titanium reagent

A short and facile synthesis of a series of 1,2-dihydroquiazolin-4(3H)-ones was accomplished in good yields via the novel reductive cyclisation of o-nitrobenzamides with aldehydes or ketones promoted by the TiCl4/Sm system. Structures were established on the basis of elemental analysis, IR, 1H NMR and confirmed by a single-crystal X-ray diffraction analysis. The advantages of our method are easily accessible starting materials, convenient manipulation and moderate to high yields.