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A new class of readily available, air-stable chiral phosphine-aminophosphine ligands were utilized for the enantioselective hydrogenation of various [alpha]-enol ester phosphonates and [alpha]-enamido phosphonates. The new phosphine-aminophosphine ligands were observed to exhibit superior enantioselectivity compared to BoPhoz analogues.

The Diels-Alder (DA) reactions of various substituted ethenes, styrene and methyl vinyl ketone with omicron-quinone methides are studied by means of density functional theory (DFT). The results indicate that the hydrogen-bond formation between chloroform and the carbonyl oxygen of the omicron-QM lowers the activation energies and increases the asynchronicity.

Several [beta]-substituted or unsubstituted [alpha]-(phthalimidomethyl)acrylates in good to excellent enantioselectivities were obtained by using a series of BoPhoz-type ligands in the rhodium-catalyzed asymmetric hydrogenation. The results suggest that an N-H proton on the amino unit of BoPhoz-type ligand is critical for high stereocontrol transformation.

Diversified 2-alkoxy- and 2-aroxy-3-substituted quinolines are prepared from o-alkynylaryl isocyanides and alcohols and phenols promoted by DABCO. The reaction is initiated by nucleophilic addition of DABCO to isocyanide and subsequent cyclization, which has led to a DABCO-quinoline-based adduct as the reactive intermediate, followed by substitution of the DABCO moiety with oxygenated nucleophiles.

The various mechanisms involved in the enantioselective Rh-catalyzed hydrogenation of [beta], [gamma]-unsaturated phosphonates with the chiral ferrocene-based monophosphoramidite ligands are discussed. The process is shown to be extremely useful for the synthesis of chiral alkylphosphonates.

An enantioselective synthesis of optically active 1-aryl or 1-alkyl substituted ethylphosphonates is developed that is based on the first Rh-catalyzed asymmetric hydrogenation of [alpha],[beta]-unsaturated precursors with a P-stereogenic BoPhoz-type ligand under mild condition. A wide range of 1-aryl or 1-alkyl substituted ethylphosphonates are achieved.

The application of the Cu-catalyzed asymmetric 1,4-reductions of [gamma]-phthalimido-substituted [alpha],[beta]-unsaturated carboxylic acid esters for an effective and enantioselective synthesis of a new series of [beta]-aryl-[gamma]-amino acid derivatives is discussed. A chiral pharmaceutical, (R)-baclofen has also been prepared by employing this approach.

The synthesis of both enantiomers of carambolaflavone A, the antidiabetic and flavonoid C-glycoside, was achieved for the first time via a 12-longest-linear-step with 16% (L-fucose) and 11% (d-fucose) overall yields. Through the synthetic investigation, the adverse effect of 4A MS in Suzuki C-glycosylation was disclosed, the mechanism of hydrogen-bonded-phenol involved Suzuki C-glycosylation was clarified, and the authentic structure of carambolaflavone A was also determined. [ABSTRACT FROM AUTHOR]

The chiral triazole carbene and Ti(OPr-i)4 cocatalyzed reaction between α,β-unsaturated aldehydes and 2-(aroylvinyl)benzaldehydes was systematically studied. A divergence in reaction pathways was observed under different reaction conditions. In benzene solvent and at ambient temperature, the reaction produced 4,5-dihydro-1,4-methanobenzo[c]oxepin-3-ones, the bridged caprolactones, as the major products in moderate yields with excellent enantioselectivity. The same reaction in dichloroethane and at 50 °C, however, gave 2,8-dihydrocyclopenta[a]indenes as the major products in most cases. The application of the method developed was demonstrated by the transformation of the bridged lactone products into enantiopure 4-hydroxy-1,2,3,4-tetrahydronaphthalene-2-carboxylic acids. [ABSTRACT FROM AUTHOR]

The cooperative chiral N-heterocyclic carbene and Lewis acid catalyzed reactions between 2-aroylvinylcinnamaldehydes and various aromatic aldehydes produced multifunctional tetrahydroindeno[1,2-c]furan-1-ones with excellent enantioselectivity. This work developed a versatile and efficient method for highly enantioselective construction of chiral tetrahydroindeno[1,2-c]furan-1-one, which are not easily prepared by other synthetic methods. [ABSTRACT FROM AUTHOR]

Based on the selectivity of deprotonation of 5,5'-bistrimethylsilyl-2,3'-bithiophene (4) in the presence of n-BuLi, three new cyclooctatetrathiophenes (COThs), COTh-1, COTh-2, and COTh-3 have been efficiently developed via intermolecular or intramolecular cyclizations. Their crystal structures clearly show that the different connectivity sequence of the thiophene rings in the molecules. The CV data and UV-vis absorbance spectra of COThs are also described. In addition, the time-dependent density functional theory (TDDFT) calculations accurately reproduce experimental observations and afford band assignment. [ABSTRACT FROM AUTHOR]

A range of ketone-stabilized phosphonium ylides were allylated with high regioselectivity by primary allylic amines in the presence of 5 mol % Pd(PPh3)4 and 10 mol % B(OH)3, and subsequent one-pot Wittig olefination gave structurally diverse a,ß-unsaturated ketones in good to excellent overall yields with excellent E selectivity. The one-pot allylation/olefination reaction was extended to ester- and nitrile-stabilized phosphonium ylides by replacing B(OH)3 with TsOH, and the corresponding a,ß-unsaturated esters and nitriles were obtained in moderate overall yields. [ABSTRACT FROM AUTHOR]

A well-defined NHC--Pd (II)--Im complex 1 was found to be an effective catalyst for the Suzuki--Miyaura coupling of aryl sulfonates including tosylates and phenylsulfonates with arylboronic acids, giving the desired coupling products in good to high yields. Acceptable yields can also be achieved even by using the less reactive mesylates as the substrates. It is worthy of noting here that this is the first example of NHC--Pd (II) complex-catalyzed Suzuki--Miyaura coupling of aryl sulfonates with arylboronic acids, enriching an inexpensive, convenient, and alternative method for the synthesis of biaryl compounds. [ABSTRACT FROM AUTHOR]

An efficient synthesis of quinazotin-4(3H)-ones from N-arylamidines, through palladium-catalyzed intramolecular C(sp²)-H carboxamidation, has been developed. The reaction, carried out in the presence of 1.0 equiv of CuO as oxidant under atmospheric pressure of CO, provides diversified 2-aryl(alkyl)-quinazolin-4(3H)-ones in reasonable to good yields from N-aryla-midines, which are readily derived from anilines and nitriles. Compared with existing approaches to quinazolin-4(3H)-ones, the current strategy features atom-economy and step-efficiency. [ABSTRACT FROM AUTHOR]

A new class of unsymmetrical hybrid phosphine-aminophosphine ligands has been prepared from commercially available, inexpensive (S)-1-phenylethylamine through a concise synthetic procedure. These ligands are not very sensitive to air and moisture, and displayed good enantioselectivities in the Rh-catalyzed asymmetric hydrogenation of various dimethyl α-benzoyloxyethenephosphonates bearing β-aryl, β-alkyl, and β-alkoxy substituents and N-benzyloxycarbonyl α-enamido phosphonates, in which up to 97% ee was obtained. A side-by-side comparison study disclosed that these new phosphine-aminophosphine ligands showed better enantioselectivity than BoPhoz ligands. [ABSTRACT FROM AUTHOR]

Reports on the total synthesis of microtubule-stabilizing agent (-)-laulimalide. Synthetic strategy; Dihydropyran ring of fragment; Reduction of alkynyl alcohol.

Demonstrates the stereoselective synthesis of (+)polyoxin, a peptidyl nucleoside from the culture broth of Streptomyces cacoi. Synthesis of (+)-polyoxin via the coupling o the protected thymine polyoxin C; Electrophilic epoxidation of E-allyl alcohol; Sharpless epoxidation the tartrate-derived allylic alcohol; Opening of the epoxide ring for the synthesis of ortho-carbomyl polyoxamic acid.

An enantioselective synthesis of optically active 1-aryl or 1-alkyl substituted ethyiphosphonates, based on the first Rh- catalyzed asymmetric hydrogenation of corresponding α,β-unsaturated precursors with a P-stereogenic BoPhoz-type ligand under the mild condition, was developed, in which a wide range of 1-aryl or 1-alkyl substituted ethyiphosphonates were achieved in up to 98% ee. [ABSTRACT FROM AUTHOR]