•The flavones and γ-benzopyranones represent one of the most prevalent structural heterocycles in natural products.•In this manuscript, the diversity oriented synthesis of the flavones and γ-benzopyranones was accomplished by palladium catalyzed Sonogashira coupling reactions of o-acylated salicacly acid triazine esters and terminal alkynes, and sequentially, piperidine catalyzed 6-endo cyclization.•N-Methylmorpholine (NMM) significantly accelerated Pd catalyzed cross-coupling of the steric hindrined triazine esters and terminal alkynes with high efficiency and regioselectivity.•The new Pd/NMM catalyst system showed excellent functional groups tolerance for 24 examples of acylated o-alkynoylphenols derivatives.•The mechanistic experiments clearly demonstrated that NNM stabilized the catalytic palladium species, and promoted the leaving of triazine moiety during the catalytic cycle.•Under very mild condition, piperazine efficiently catalyzed 6-endo cyclization of the acylated o-alkynoylphenols derivatives, affording 24 examples of γ-benzopyranones with excellent yields.Lewis base, N-methylmorpholine (NMM) accelerated Pd-catalyzed Sonogashira coupling of steric hindered super active esters, 1a–1e, and terminal alkynes. This approach provided an efficient synthetic protocol for a broad array of acylated o-alkynoylphenols compounds, 3a–3e, under moderate conditions. The mechanistic study clearly demonstrated that NNM stabilized the catalytic palladium species, and accelerated the leaving of triazine moiety during the catalytic cycle of the cross-coupling reactions. In addition, piperazine was found to efficiently catalyze the 6-endo cyclization of acylated o-alkynoylphenols, which achieved the diversity oriented synthesis of γ-benzopyranones, 4aa–4eg, with 93–99% yields.

A class of sawhorse-type ruthenium(I) complexes featuring a stable CORM sphere with diverse carboxylic and amino acid derivatives were synthesized and validated as lead structures for photo-activated CO-releasing molecules (PhotoCORMs). The CO release of these CORMs was triggered by 365 nm UV irradiation. Cell viability studies indicated that 3a and 3f were non-toxic both in the dark and in UV light, making them excellent lead structures for therapeutic CORMs.

Thermolysis of triruthenium dodecacarbonyl Ru3(CO)12 with picolinic acid, 2-furoic acid and 2-thiophenecarboxylic acid was thoroughly studied. Three ruthenium carbonyl products, Ru4(CO)8(μ2-O, η1-N-pic)4 (1) (pic = picolinate), [Ru2(CO)4(fur)2]m (2) (fur = 2-furoate) and [Ru2(CO)4(thi)2]n (3) (thi = 2-thiophenecarboxylate) were isolated. Single crystal X-ray crystallography revealed that compound 1 is a tetraruthenium cluster with two Ru2(CO)4 units in an unexpected criss–cross geometry, while compounds 2 and 3 exhibit the classical sawhorse structure. Compound 1 was stable to common donor ligands and formed solvated compounds Ru4(CO)8(μ2-O, η1-N-pic)4·H2O (4) and Ru4(CO)8(μ2-O, η1-N-pic)4·CH3CN (5) in hydrous toluene and acetonitrile, respectively; compounds 2 and 3 converted into monomers Ru2(CO)4(fur)2(H2O)2·H2O (2b) and Ru2(CO)4(thi)2(CH3OH)2·CH3OH (3b) in hydrous dichloromethane and acetonitrile, respectively. [Ru2(CO)4(pic)2]2 (1a), Ru2(fur)2(CO)6 (2a) and Ru2(thi)2(CO)6 (3a) were proposed as the corresponding intermediates of 1–3 based on in situ FT-IR spectroscopy, LC-MS and the molecular structures of the known ruthenium carbonyl carboxylates.

An efficient catalytic system involving in situ activation of kinetically inert titanocene dichloride with alcoholic solvent for the synthesis of quinazoline derivatives was developed. 1 mol% Cp2TiCl2 at 30 °C afforded 17 examples of quinazoline derivatives with yields of 95–98% in 7–12 minutes. Mechanistic experiments using in situ NMR and HRMS established that the coordination of ethanol to the titanocene moiety released the catalytic species [Cp2Ti(OCH2CH3)2].

A water-accelerated Pd catalyzed Suzuki–Miyaura cross-coupling reaction was developed for the synthesis of thiophenyl triazine conjugates (TTCs). The compounds (2a–2e and 3a–3e) with five σ-spacers were obtained and fully characterized. The X-ray analysis of 2a, 2d, and 3d found that the length of the intermolecular H bond was 3.465(3) Å and the π–π interactions ranged from 3.6538(2)–3.9519(1) Å. Five σ-spacers of TTCs had an effect on their emissions from blue (363 nm) to yellow (530 nm) whilst 2- and 3-thiophenyl chromophores finely tune the emission from 530 to 504 nm. The DFT computation showed the TTCs had low HOMO (−6.8 eV) and LUMO (−2.5 eV) energy and high triplet energy (ET, 2.4 eV). The energy level and gap of TTCs were regularly modulated by the σ-spacer.

A neat palladium-catalyzed alkynylation reaction was developed with “super-active ester” as the carbonyl electrophile, which provides a clean and efficient synthetic protocol for a broad array of ynone compounds under CO-, Cu-, ligand-, and base-free conditions. The superior activity of triazine ester was rationalized by the strong electron-withdrawing ability and the unique affinity of triazine on palladium. A mechanistic experiment clearly demonstrated that the N–Pd coordination of triazine plays a crucial role for the highly efficient C–O activation.

A ubiquitous accelerating effect of chlorobenzene (PhCl) was observed unexpectedly in the Pd-catalyzed cascade Sonogashira–hydroarylation reaction. This new type of carbon–carbon bond forming cross-coupling reaction was efficiently catalysed by Pd2(dba)3 in the presence of a catalytic amount of PhCl, which provides a facile and direct approach to the synthesis of trisubstituted olefins.

To explore the true identity of palladium-catalyzed Sonogashira coupling reaction, montmorillonite (MMT)-supported transition metal nanoparticles (MMT@M, M = Pd, Cu, Fe, and Ni) were prepared, characterized, and evaluated systematically. Among all MMT@M catalysts, MMT@Pd/Cu showed the highest activity, and it was successfully extended to 20 examples with 57%–97% yields. The morphology characterization of MMT@Pd/Cu revealed that the crystalline bimetallic particles were dispersed on a MMT layer as nanoalloy with diameters ranged from 10 to 11 nm. In situ IR analysis using CO as molecular probe and XPS characterization found that the surface of Pd/Cu particles consisted of both catalytic active sites of Pd(0) and Cu(I). The experiments on the catalytic activities of MMT@M found that Pd/Cu catalyst system exhibited high activity only in nanoalloy form. Therefore, the Pd/Cu nanoalloy was identified as catalyst, on which the interatom Pd/Cu transmetalation between surfaces was proposed to be responsible for its synergistic activity.Keywords: bimetallic catalysis; CO absorption; montmorillonite; nanoalloy; Sonogashira coupling

•Efflorescent pottery samples are abundant in water-soluble salts.•Chloride, nitrate and sulphate were detected in efflorescent products.•Chloride is the main type of water-soluble anion, occurring as NaCl, CaCl2, BaCl2 and KCl.•Water-soluble salts in pottery are derived from the atmosphere during long-term storage.Ancient pottery stored in northern Chinese museums is apt to powder during long-term storage. A detailed investigation of the efflorescent products of such pottery was performed to shed light on the role of water-soluble salts, a type of curing-salt-laden colloidal substance that shows smooth edges and shrinkage holes containing Cl−, NO2−, NO3−, SO42−, Na+, K+, Ca2+, etc., in pottery efflorescence. For comparison, recent specimens of pottery, buried soil and storeroom dust were characterised as well, demonstrating that, in this samples, water-soluble salts mainly originated from the surrounding atmosphere.

•A green system for metal- and surfactant-free Mannich reactions was established.•5-Sulfosalicylic acid is superior recyclable water-soluble organocatalyst.•The catalytic Mannich reactions afforded β-amino ketones with excellent yields.•The catalyst can be recycled in water whereas the product isolated by filtration.•A new single crystal confirmed the anti-conguration of products.A water-soluble Brønsted acid, 5-sulfosalicylic acid, efficiently catalyzed the direct three-component Mannich reactions of cyclohexanone and 3-pentanone in pure water. 21 Examples of Mannich reactions were presented, which afforded the corresponding β-amino ketones with up to 97% yield and decent diastereoselectivities. The acid catalyst can be recycled as an aqueous solution for at least six times and the yield of the Mannich product remained over 90%.

A class of sawhorse-type ruthenium(I) complexes featuring a stable CORM sphere with diverse carboxylic and amino acid derivatives were synthesized and validated as lead structures for photo-activated CO-releasing molecules (PhotoCORMs). The CO release of these CORMs was triggered by 365 nm UV irradiation. Cell viability studies indicated that 3a and 3f were non-toxic both in the dark and in UV light, making them excellent lead structures for therapeutic CORMs.