Jianhua Liao

Palladium-Catalyzed Desulfitative Oxidative Coupling between Arenesulfinic Acid Salts and Allylic Alcohols: A Strategy for the Selective Construction of β-Aryl Ketones and Aldehydes.

An efficient palladium-catalyzed desulfitative oxidative coupling of sodium arylsulfinites for highly region-selective Heck-type reaction of allylic alcohols has been developed. The compatibility of the functionalities of -I, -Br, and -F would explore further postfunctionalization of the C-X bonds. This method provides a new and straightforward protocol for the synthesis of β-aryl ketones and aldehydes. The deuterium labeling experiments indicated that this transformation may proceed via a [1, 2-H] shift process.

A Four‐Component Reaction Strategy for Pyrimidine Carboxamide Synthesis

Demonstrated herein is a highly effective 3 starting materials-4 component reaction (3SM-4CR) strategy for the synthesis of pyrimidine carboxamides from amidines, styrene, and N,N-dimethylformamide (DMF) by a palladium-catalyzed oxidative process. This transformation represents the first example of employing DMF as a dual synthon, a one-carbon-atom synthon and amide synthon, and was proven by isotope-labeling experiments. Additionally, the combination of C-H bond functionalization and cross-dehydrogenative coupling processes affords four chemical bond formations. This sequential 3SM-4CR strategy features inexpensive, readily available starting materials, green oxidants, as well as atom and step economy. It leads to the preparation of pyrimidine carboxamides and has potential applications in the pharmaceutical industry.

Transition Metal Free Intermolecular Direct Oxidative C–N Bond Formation to Polysubstituted Pyrimidines Using Molecular Oxygen as the Sole Oxidant

Various polysubstituted pyrimidines are smoothly formed via a base-promoted intermolecular oxidation C-N bond formation of allylic C(sp(3))-H and vinylic C(sp(2))-H of allyllic compounds with amidines using O2 as the sole oxidant. This protocol features protecting group free nitrogen sources, good functional group tolerance, high atom economy, and environmental advantages.

Amide Oxygen-Assisted Palladium-Catalyzed Hydration of Alkynes

Herein, an amide oxygen-assisted palladium-catalyzed hydration reaction of alkynes is realized to prepare a series of o-acylacetanilide derivatives with high yield, and single regioselectivity under mild reaction conditions. This transformation is simple, practical, and can be performed on a gram scale. Evaluation of the mechanism shows that the reaction should involve an oxypalladation process, and the 1,3-oxazine compound is proven to be a key intermediate.

Metal-Free Catalyzed Regioselective Allylic Trifluoromethanesulfonylation of Aromatic Allylic Alcohols with Sodium Trifluoromethanesulfinate

An efficient procedure for the preparation of allylic trifluoromethanesulfones with high regioselectivity from aromatic allylic alcohols/esters and NaSO2CF3 under transition-metal-free conditions is described. A wide range of functional groups were tolerated. This is the first example to realize different types of allylic alcohols, including primary, secondary, and tertiary allylic alcohols, all of which transferred to the corresponding products efficiently in good to excellent yields with readily available and inexpensive NaSO2CF3. The synthetic utility of the method was demonstrated by performing the reaction at gram scale.

Intermolecular Asymmetric Carboesterification of Alkenes by Using Chiral Amine Auxiliaries under O2: Synthesis of Enantioenriched α-Methylene-γ-Lactones through Chloropalladation of Alkynes

Herein, the first example of chloropalladation-initiated asymmetric intermolecular carboesterification of alkenes with alkynes by using chiral amine auxiliaries is reported. The use of (1S,2S)-N(1),N(1)-dimethylcyclohexane-1,2-diamine auxiliaries is essential for providing α-methylene-γ-lactones products in moderate to high yields and excellent enantioselectivities at room temperature. Moreover, the chiral amine auxiliaries can be readily removed by hydrolysis during the reaction process to keep the absolute configuration. This oxygen- and water-promoted asymmetric reaction opens a new window to study asymmetric processes in halopalladation reactions.

Palladium-Catalyzed Fluoroalkylative Cyclization of Olefins

A palladium-catalyzed fluoroalkylative cyclization of olefins with readily available Rf-I reagents to afford the corresponding fluoroalkylated 2,3-dihydrobenzofuran and indolin derivatives with moderate to excellent yields is reported. This novel procedure provides an efficient method for the construction of Csp3-CF2 and C-O/N bonds in one step. A wide range of functional groups are tolerated. It is proposed that a radical/SET (single electron transfer) pathway proceeding via the fluoroalkyl radical may be involved in the catalytic cycle.

Development of Isostructural Porphyrin–Salen Chiral Metal–Organic Frameworks through Postsynthetic Metalation Based on Single-Crystal to Single-Crystal Transformation

The development of well-defined multimetallic porous metal-organic frameworks (MOFs) will add a new dimension to the application of MOF catalysis. From this perspective, the understanding and tailoring of the catalytic metal sites in MOFs are key fundamental challenges that could reveal the intrinsic potential of these materials. In this work, a series of porphyrin-salen chiral MOFs (ps-CMOFs 2-7) have been synthesized through postsynthetic metalation (PSMet) of the parent ps-CMOF via single-crystal to single-crystal transformation. Crystal structures of these ps-CMOF analogues revealed the same topological structure but varied metal entities compared to those of the parent framework. Note that the PSMet process involves three methods involving cation exchange at the nodes, cation exchange at the metalated porphyrin, and cation addition at the free porphyrin, which has been systematically investigated using single-crystal X-ray diffraction and other physicochemical methods. The N2 adsorption tests, thermogravimetric analysis, and powder X-ray diffraction of 2-7 showed curves or patterns similar to those of 1, indicating the maintenance of the crystallinity, porosity, and thermal stability of the framework during the PSMet process. In addition, 2-7 showed distinctly improved adsorption capacities and isosteric heats of adsorption (Qst) for CO2 compared to those of their parent counterpart. Lastly, as a representative example of the ps-CMOF catalytic platform, 5 proved to be an efficient recyclable heterogeneous catalyst for the asymmetric addition reaction of CO2 with epoxides under mild conditions. Furthermore, because of the constrained chiral environment within ps-CMOF, the enantioselectivity of this reaction appears to be dependent on substrate size.

Palladium-Catalyzed Aerobic Oxygenation of Allylarenes

An efficient and practical protocol for the synthesis of (E)-allylethers from readily available olefins with alcohols or phenols was developed. This aerobic oxidative allylic C-H oxygenation protocol features mild conditions, broad substrate scope, and high atom and step economy, making it a valuable and convenient synthetic method. Notably, molecular oxygen is the sole oxidant in this novel transformation.

Cu-Catalyzed intermolecular [3 + 3] annulation involving oxidative activation of an unreactive C(sp3)–H bond: access to pyrimidine derivatives from amidines and ketones

A facile and efficient approach for the synthesis of various pyrimidine derivatives from amidines and ketones via a Cu-catalyzed intermolecular oxidative coupling process using TEMPO/O2 as a co-oxidant has been developed. This novel protocol features unreactive C(sp3)–H bond amination, a wide range of substrates, good functional group tolerance and mild reaction conditions.