The combination of a new bifunctional phosphine and an acrylate generate a zwitterion in situ and it serves as an efficient catalyst for asymmetric reactions through a homogeneous ion-pairing mode. This new catalytic system has been successfully applied to Mannich-type reactions to give excellent results and it demonstrates a broad substrate scope. Such reactivity is not accessible with general organophosphine catalytic modes. Preliminary investigations into the mechanism are also presented.

The combination of a new bifunctional phosphine and an acrylate generate a zwitterion in situ and it serves as an efficient catalyst for asymmetric reactions through a homogeneous ion-pairing mode. This new catalytic system has been successfully applied to Mannich-type reactions to give excellent results and it demonstrates a broad substrate scope. Such reactivity is not accessible with general organophosphine catalytic modes. Preliminary investigations into the mechanism are also presented.

A novel family of dipeptide-based multifunctional quaternary phosphonium salts has been developed as chiral phase-transfer catalysts, which feature ready accessibility and structure modularity, allowing easy fine-tunings of activity. They demonstrated high efficiency in catalyzing the tandem asymmetric Michael addition/intramolecular S_N2 reaction between 6 or 7-substituted conjugate enones and malonates, providing synthetically important five or six-membered carbocycles and heterocycles in good yields and with good to excellent enantioselectivities.

A formal total synthesis of iridoid 9-deoxygelsemide has been accomplished. Our approach features the use of (S)-carvone as starting material, Favorskii rearrangement to construct the functionalized cyclopentane core, Chugeav elimination to introduce the endocyclic double bond, and the ring-opening reaction of epoxide to build the second five-membered ring.

The asymmetric epoxidation of α,β-unsaturated ketones has been achieved by using functional and readily accessible primary-secondary diamines as the catalysts, giving the useful alkyl epoxy products with good yields and high enantioselectivities (up to 99% ee).

The effect of metallic ions on the nitrolysis of DAPT [3,7-diacetyl-1,3,5,7-tetraazabicyclo(3.3.1)nonane] and HA (hexamine) was investigated by experimental and theoretical approaches. The combinatorial reagent, M(NO⁻₃)_n/Ac₂/NH₄NO₃ (M=Mg²⁺, Cu²⁺, Pb²⁺, Bi³⁺, Fe³⁺ and Zr⁴⁺), was found to be efficient in the experiment of the nitrolysis of DAPT. A key intermediate during the nitrolysis of DAPT was detected by ¹H NMR. The formation mechanism of the intermediate was proposed and analyzed. Some discrepant results for the nitrolysis of DAPT and HA catalyzed by different metallic nitrates were explained based on hard-soft and acid-base principle and stabilized energy of ion-complex. From the latter point of view, some cations with high polarizable ligands, e.g., OSO₂CF₃⁻, (CF₃SO₂)₂N⁻, and (C₄F₉SO₂)₂N⁻, can increase the yields. Two newly designed catalysts, Cu[(CF₃SO₂)₂N]₂ and Cu[(C₄F₉SO₂)₂N]₂, were tested to be highly efficient.

An enantioselective Michael addition of ethyl 4,4,4-trifluoro-3-oxobutanoate to α,β-unsaturated ketone esters using a chiral alkyl-substituted thiourea catalyst is reported. Excellent levels of stereo-induction (up to 98% ee) under mild reaction conditions were obtained to afford the corresponding α-trifluoromethyldihydropyrans.

A novel and facile preparation of 1,1-difluoroallyl substituted five-membered lactones or pyrrolidines in moderate yields through direct double electrophilic fluorination of 4,5-allenoic acids or tosylamides with Selectfluor^TM F-TEAD-BF₄ is described.

A highly enantioselective Michael addition of cyclic 1,3-dicarbonyl compounds to β,γ-unsaturated α-keto esters catalyzed by amino acid-derived thiourea-tertiary-amine catalysts is presented. Using 5 mol% of a novel tyrosine-derived thiourea catalyst, a series of chiral coumarin derivatives were obtained in excellent yields (up to 99%) and with up to 96% ee under very mild conditions within a short reaction time.

The stereoselective total synthesis of fasicularin (1) andlepadiformine A (2) is described, which features the utilization of a Zn-mediated allylation of a chiral, aliphatic, N-tert-butanesulfinyl ketimine to construct the amino-substituted quaternary carbon center in good yield and with excellent diastereoselectivity. The azaspirocyclic scaffold was installed sequentially by a Sharpless dihydroxylation and an internal epoxide-opening reaction, and this scaffold was further converted into common intermediate 5. Removing the tosyl (Ts) protecting group of 5 and reductively aminating usingLuche's reagent completed the synthesis of (–)-fasicularin (1), while reducing 5 using L-selectride, deprotecting the Ts group, and finishing with an intramolecular amino alcohol cyclocondensation completed the total synthesis of (–)-lepadiformine A (2).

A general and practical method of allylation of carbonyl compounds promoted by p-nitrobenzoic acid under mild reaction condition has been developed. p-Nitrobenzoic acid can be easily recovered after workup by aqueous HCl.

Density functional theory investigation of ¹⁴N nuclear quadrupole coupling constants (NQCC) for HMX polymorphs was performed. During the calculation of NQCC and asymmetry parameter (η) of β-HMX, single molecule model is found to be worse than cluster model. The calculated results are more sensitive to the proper model than to the basis set. The calculation for β-HMX using cluster model at B3LYP/6-311++G(d,p) level gives better agreement with experiment. This approach was subsequently applied to α, γ, and δ-HMXs. The difference of simulated ¹⁴N NQR frequency was found. The NQR spectrum is useful for the study of explosive or propellant on their detection, phase transition, and aging process.

The mechanism of nitrolysis of hexamine (HA) by DFT method has been explored to understand the classical organic reaction and assist the design of new catalyst. The potential energy surface of NO⁺₂ was firstly investigated. A reasonable configuration evolution of NO⁺₂ during the process of its reaction with HA was figured out. The role of H⁺ and NH⁺₄ for the nitrolysis of HA was analyzed and discussed. The route of nitrolysis reaction from HA to 1-acetoxylmethene-3-nitro-tetrazabicyclo[3,3,1]nonane intermediate is similar to that of acetylation of HA. The relative free energy calculation proves the priority of nitrolysis relative to acetylation. Two types of Lewis salts, M(OSO₂CF₃)₃ and M[N(SO₂CF₃)₂]₃ (M: Yb, Sm, Y, and Eu), are designed on the basis of discussed mechanism. The calculation for the key bond order in IM2[CH₂R] model intermediates gives an indicator as the preferable catalyst. The experimental results support the theoretical conclusion.

The asymmetric epoxidation of electron-deficient olefins has been achieved using inexpensive and readily available prolinols as catalysts with good to excellent yields and enantioselectivities. The utility of the resulting chiral epoxides was illustrated by elaboration to several synthetically useful compounds featuring a concise synthesis of (−)-(5R,6S)-balasubramide.

An asymmetric Michael addition of α-substituted cyano ketones to β,γ-unsaturated α-keto esters to form chiral dihydropyrans catalyzed by a series of α-amino acid-derived thiourea-tertiary amines is presented. A novel tyrosine-derived thiourea catalyst was identified as the optimal catalyst providing the desired product in 91–95% yields and with 90–96% ee at a low catalyst loading of 2.0 mol%. The utility of the reaction was exemplified by facile conversion of the dihydropyran product into pharmaceutically useful dihydropyridine.

A series of chiral substituted 5-(pyrrolidin-2-yl)tetrazoles have been synthesized and evaluated as organocatalysts for the asymmetric Biginelli reaction. The relationship between catalytic activity and the different catalyst structures is briefly discussed. By using the optimized catalyst C¹⁰ (10 mol-%), a series of 3,4-dihydropyrimidin-2(1H)-one (DHPM) derivatives have been obtained in 63–88 % yields and 68–81 % ee values within 24 h at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A convenient method to synthesize a series of monofluoro γ-lactones and pyrrolidine derivatives in moderate to good yields via the electrophilic fluorination of γ-allenoic acids and tosylamides using Selectfluor was developed.

A general stereoselective synthetic route to 5-substituted and 5,8-disubstituted indolizidine alkaloids has been developed starting from commercially available L-proline. (−)-Indolizidines 209D and 209B were efficiently synthesized in 9.8% and 14.8% overall yields in seven and five-step reactions from readily available aldehyde 3 and ketone 10, respectively. The key steps of this synthesis involve a substrate-induced asymmetric addition of ethyl lithiopropiolate to aldehyde 3 or methyl ketone 10, and a two-step one-pot hydrogenation/cyclization sequence to construct the bicyclic skeleton.

The three-component reactions of aromatic aldehydes, amines and allyltributylstannane in water catalyzed by phosphomolybdic acid (PMA), underwent smoothly to afford the corresponding homoallylic amines in high yields at room temperature.

The asymmetric construction of quaternary carbon centers via cross-aldol reactions of ketones with β,γ-unsaturated keto esters catalyzed by 4-(tert-butyldiphenylsilyloxy)-pyrrolidine-2-carboxylic acid in water is described. The adducts bearing two adjacent chiral centers were obtained in high yields, mostly up to 99% ee, and with high diastereoselectivities. The corresponding polyfunctional products could also be easily transformed to useful lactones with three chiral centers.