Chemoselective Synthesis of 3-Bromomethyloxindoles via Visible-Light-Induced Radical Cascade Bromocyclization of Alkenes.

A novel visible-light-induced radical cascade bromocyclization of N-arylacrylamides has been accomplished. This reaction overcomes the overbromination at the benzene rings suffered in traditional electrophilic reactions, thus enabling the first highly chemoselective synthesis of valuable 3-bromomethyloxindoles. The combination of pyridine and anhydrous medium is identified as the key factor for the high chemoselectivity in the current photoreaction system, which might work by suppressing the in situ generation of low-concentration Br2 from N-bromosuccinimide. Moreover, the mild reaction conditions ensure the generation of a wide range of the new desired products with excellent functional group tolerance.

Metal-Catalyst-Free One-Pot Aqueous Synthesis of trans-1,2-Diols from Electron-Deficient α,ß-Unsaturated Amides via Epoxidation Using Oxone as a Dual Role Reagent.

In organic synthesis, incorporating two functional groups into the carbon-carbon double bond of α,ß-unsaturated amides is challenging due to the electron-deficient nature of the olefin moiety. Although a few examples of dihydroxylation of α,ß-unsaturated amides have been demonstrated, producing cis-1,2-diols using either highly toxic OsO4 or other specialized metal reagents in organic solvents, they are limited to several specific amides. We describe herein a general and one-pot direct synthesis of trans-1,2-diols from electron-deficient α,ß-unsaturated amides through dihydroxylation using oxone as a dual-role reagent in water. This reaction does not require any metal catalyst and produces non-hazardous and nontoxic K2 SO4 as the sole byproduct. Moreover, epoxidation products could also be selectively formed by adjusting the reaction conditions. By the strategy, the intermediates of Mcl-1 inhibitor and antiallergic bioactive molecule can be synthesized in one pot. The gram-scale synthesis of trans-1,2-diol which is isolated and purified by recrystallization further shows the potential applications of this new reaction in organic synthesis.

Discovery of an Oxidative System for Radical Generation from Csp3-H Bonds: A Synthesis of Functionalized Oxindoles.

A facile and versatile method for generating radicals from Csp3-H bonds under metal-free and organic-peroxide-free conditions was developed. By combining safe persulfate and low-toxic quaternary ammonium salt, a wide variety of Csp3-H compounds including ethers, (hetero)aromatic/aliphatic ketones, alkylbenzenes, alkylheterocycles, cycloalkanes, and haloalkanes were selectively activated to generate the corresponding C-centered radicals, which could be further captured by N-arylacrylamides to deliver the valuable functionalized oxindoles. Good functional group tolerance was demonstrated. The useful polycarbonyl compound and esters were also modified with the strategy. Moreover, the combination can also be applied to the practical coupling between simple haloalkanes and N-hydroxyphthalimide (NHPI).

C(sp3)-H Monoarylation of Methanol Enabled by a Bidentate Auxiliary.

With the assistance of a practical directing group (COAQ), the first catalytic protocol for the palladium-catalyzed C(sp3)-H monoarylation of methanol has been developed, offering an invaluable synthesis means to establish extensive derivatives of crucial arylmethanol functional fragments. Furthermore, the gram-scale reaction, broad substrate scope, excellent functional group compatibility, and even the practical synthesis of medicines further demonstrate the usefulness of this strategy.

An efficient iodine pentoxide-triggered iodocarbocyclization for the synthesis of iodooxindoles in water.

An efficient iodocarbocyclization of alkenes for the synthesis of iodooxindoles has been developed. This reaction proceeds in a chemoselective manner and shows excellent tolerance of various functional groups, including a chemosensitive hydroxymethyl group. Nonmetal inorganic iodine pentoxide was used as both the oxidant and iodine source, making this protocol very practical. On the basis of experimental observations, a plausible electrophilic reaction mechanism was proposed.

Transition-Metal-Free Oxidative Aminooxyarylation of Alkenes: Annulations toward Aminooxylated Oxindoles.

An efficient oxidative aminooxyarylation of alkenes under a transition-metal-free condition was described. Under the reaction conditions, N-hydroxyphthalimide (NHPI) reacted readily with N-arylacrylamides to produce cyclic products via a radical C-H functionalization process, achieving both C-O and C-C bonds formation in one pot. This reaction provided a facile access to the valuable aminooxylated oxindoles. The benzylic and α-methylene C(sp3)-H bonds were also aminooxylated under the reaction conditions.

Transition-Metal-Free TBAI-Facilitated Addition-Cyclization of N-Methyl-N-arylacrylamides with Arylaldehydes or Benzenesulfonohydrazides: Access to Carbonyl- and Sulfone-Containing N-Methyloxindoles.

A highly efficient addition-cyclization of N-methyl-N-arylacrylamides with arylaldehydes or benzenesulfonohydrazides was developed using a catalytic amount of the quaternary ammonium salt (TBAI) under metal-free conditions, leading to the carbonyl- and sulfone-containing oxindoles. Compared to previous methods, which require excessive amounts of explosive organic peroxides and precious or toxic metal reagents, the present protocol, which gave access to 3,3-disubstituted oxindoles, is a safe and green approach, resulting in the formation of various useful carbonyl- and sulfone-containing oxindoles in yields of 40-94%.

Transition-Metal-Free Synthesis of Carbonyl-Containing Oxindoles from N-Arylacrylamides and α-Diketones via TBHP- or Oxone-Mediated Oxidative Cleavage of C(sp(2))-C(sp(2)) Bonds.

Carbonyl-containing oxindoles can be prepared from N-arylacrylamides and α-diketones by TBHP- or oxone (KHSO5)-mediated C(sp(2))-C(sp(2)) bond cleavage and new C(sp(2))-C(sp(3)) bond formation. This methodology is characterized by its simple and transition-metal-free conditions and good functional group compatibility utilizing inexpensive and readily available reagents, thus providing a practical and efficient approach to an important class of 3-(2-oxoethyl)indolin-2-ones which are highly valued synthetic intermediates of biologically active molecules. In this transformation, alkylcarbonyl-containing oxindoles were obtained in majority when N-arylacrylamides reacted with asymmetric aliphatic/aromatic α-diketones. On the basis of the preliminary experiments, a plausible mechanism of this transformation is disclosed.

Metal-free synthesis of oxindoles via (NH4)2S2O8-mediated halocarbocyclization of alkenes in water.

A metal-free synthesis of oxindoles was achieved through the (NH4)2S2O8-mediated halocarbocyclization of alkenes. This protocol provides a practical and environmentally benign method for the construction of halo-containing oxindoles in water. The advantages of this reaction are its good functional group tolerance and mild reaction conditions. On the basis of experimental observations, a plausible reaction mechanism is proposed.

[Effect of exogenous iron on accumulation and chemical forms of cadmium, and physiological characterization in different varieties of tomato].

Pot experiments were carried out to investigate the influence of different iron (Fe) levels (0, 50, 100, 200 and 400 micromol.L-1) on the plant growth, activities of antioxidant enzymes, accumulation and chemical forms of cadmium (Cd) in tomato when exposed to Cd (10 mg.kg-1). The results showed that dry weights of fruit, roots, stem, leaf, and plant, and concentration and accumulation of Cd significantly differed between the two varieties of tomato tested. Dry weights of fruit, roots, stem, leaf, and plant increased in the presence of Fe. Activities of superoxide dismutase (SOD) of root in both varieties, and activities of catalase (CAT) of root in Yufenl09 deceased at first, and then increased with increasing levels of Fe, but activities of peroxidase (POD) of root in both varieties and activities of CAT of root in 4641 increased at first, and then reduced with increasing levels of Fe. Chemical forms of Cd in fruit of tomato were in the order of FR > FHCl > FE > FNaCl > FHAC > FW. All chemical forms of Cd obviously decreased after the application of adequate Fe compared to the control, while FHcI and FR of 4641, and the total extractable Cd, FE, FNaCl and FR of Yufenl09 increased at 400 micromol.L-1Fe treatment. Cadmium accumulations of tomato were in the order of leaf > stew > fruit > roots. Cadmium concentration in leaf, stem, roots and fruit of both varieties decreased by 7. 1% -25.3% , 30. 8% -50. 4% , 13.0% -45. 1% and 2.8% -11.7% in the presence of Fe when exposed to Cd, and the Cd concentration of fruit and Cd accumulations in plant were in the order of 4641 < Yufenl09 in the presence or absence of Fe.

[Types of arterio-portal fistula of hepatocellular carcinoma patients on helical computed tomography and digital subtraction angiography].

OBJECTIVE: To analyse the pathogenesis of the hepatocellular carcinoma (HCC) with arterio-portal fistula (APF) and the types of these APF on helical CT (HCT) and digital subtraction angiography (DSA), and to study the interventional therapy for HCC patients with APF. METHODS: HCC with APF in 48 patients were reported. All the patients received contrast media enhanced HCT scan and DSA examination. The APF were divided into the peripheral type, the hepatic segment type, and the center type according to the findings on HCT and DSA. RESULTS: The peripheral type of APF were found in 14 cases (14/48), the hepatic segment type in 15 cases (15/48), and the center type in 19 cases (19/48) on HCT scan, respectively. The peripheral type of APF were found in 13 cases (13/48), the hepatic segment type in 16 cases (16/48), and the center type in 19 cases (19/48) on DSA examination, respectively. The pertinency and consistency on the types of APF between HCT and DSA were compared, and the consistency rate was 85.42%; Kappa=0.779, u=7.60, P<0.01. It showed high pertinency of the types of APF between HCT and DSA. The center type APF in 11 of 19 cases disappeared, in 6 of the 19 cases partly disappeared, in 1 case was noneffective, and in 1 case was reformulation after the interventional therapy. The segment and peripheral types of APF in 20 of the 29 cases disappeared, in 8 of the 29 cases partly disappeared, and 1 case was noneffective after interventional therapy. CONCLUSION: It's vital to know well the features of various types of APF in HCC on HCT and DSA, which can bring about positive effect on interventional therapy for HCC with APF.

[Genetic diversity of mitochondrial DNA D-loop sequences in cattle breeds in Guizhou].

The complete mitochondrial D-loop sequences, 910 bp in length, in 82 individual cattle from 4 breeds in Guizhou province were analyzed. The results revealed 31 mitochondrial haplotypes, 65 polymorphic sites, covering 7.14% of the entire length of the sequence. Among these polymorphic sites, there were 62 transitions, 2 transversions and 1 coexistent site of transition and transversion. The nucleotide diversity (pi value) and haplotype diversity (H) estimated from mtDNA D-loop region in 4 cattle breeds in Guizhou varied from 2.16%-2.61% and 0.695-0.909, respectively, showing that abundant mitochondrial genetic diversity exists in Guizhou cattle breeds. The Neighbor-Joining molecular phylogenetic tree of mtDNA D-loop of 4 Guizhou cattle breeds was constructed according to the 31 haplotypes. The NJ tree indicated that the origin of cattle breeds was from Bos taurus and Bos indicus which had nearly the same influence on cattle breeds in Guizhou. The feasibility of applying nucleotide diversity (pi value) to the evaluation of bovine genetic differentiation was discussed.