Ni-Catalyzed Reductive Arylalkenylation of Alkynes for the Selective Synthesis of Polysubstituted Naphthalenes.

A Ni-catalyzed reductive arylalkenylation of alkynes with 1-bromo-2-(2-chlorovinyl)arenes in the presence of zinc powder has been developed. This base-free cyclization provides a novel protocol for the selective synthesis of 2-trifluoromethyl naphthalenes and ethyl 2-naphthoates from simple starting materials in moderate to good yields with excellent tolerance of functional groups.

Copper-Catalyzed Electrophilic Cyclization of N-Propargylamines with Sodium Sulfinate for the Synthesis of 3-Sulfonated Quinolines.

A convenient and effective protocol for the synthesis of 3-sulfonated quinolines via copper-catalyzed electrophilic cyclization of N-propargylamines has been developed, in which cheap and stable sodium sulfinates were utilized as green sulfonylation reagents. This cascade transformation involves radical addition, cyclization and dehydrogenative aromatization processes in a one-pot reaction under mild conditions.

Palladium-catalyzed dimerization of N-aryl propargylamines for the synthesis of 3-vinylquinolines.

A straightforward method for the synthesis of polyfunctionalized quinolines from readily available N-aryl propargylamines under aerobic conditions was developed. It provides convenient access to a variety of synthetically and pharmaceutically important quinolines in moderate to good yields. Control experiments suggest that the cascade reaction might proceed via the Pd-catalyzed electrophilic cyclization of N-aryl propargylamines followed by a hydroarylation process through trapping of the σ-quinolinylpalladium intermediate with a second molecule of the substrate.

One-Pot Synthesis of Quinoxalinones via Tandem Nitrosation/Cyclization of N-Aryl Cyanoacetamides.

A new one-pot strategy for the synthesis of quinoxalin-2-ones from the tandem nitrosation/cyclization reaction of N-aryl cyanoacetamides with tert-butyl nitrite has been developed. The dehydrogenative N-incorporation is achieved through a sequence of nitrosation, tautomerization, and cyclization, affording quinoxalin-2-ones in moderate to good yields with good functional group tolerance.

Copper-Catalyzed Three-Component Tandem Cyclization for One-Pot Synthesis of 1,4-Benzothiazines.

A copper-catalyzed three-component tandem reaction has been developed for the convenient and practical synthesis of 1,4-benzothiazines. A variety of terminal alkynes and 2-iodo/bromophenyl isothiocyanates underwent this one-pot cyclization with aqueous ammonia to afford 1,4-benzothiazines in moderate to good yields.

Synthesis of 2-Sulfenylindenones via One-Pot Tandem Meyer-Schuster Rearrangement and Radical Cyclization of Arylpropynols with Disulfides.

A tandem annulation of arylpropynols with disulfides has been developed for the synthesis of 2-sulfenylindenone derivatives. The reaction pathway involves one-pot tandem Meyer-Schuster rearrangement of arylpropynols and successive radical cyclization with disulfides. Various arylpropynols and disulfides with a number of functional groups are compatible in this reaction that affords the corresponding 2-sulfenylindenones in moderate to good yields.

Copper-mediated stereospecific C-H oxidative sulfenylation of terminal alkenes with disulfides.

A copper and iodine-mediated C-H oxidative sulfenylation of olefins with diaryl disulfides has been developed for the stereospecific synthesis of vinyl thioether. With the combination of Cu(OTf)2 and I2, a variety of terminal alkenes underwent oxidative coupling reaction with various diaryl disulfides successfully to afford the corresponding E-vinyl sulfides in moderate to good yields.

Copper-catalyzed ring expansion of 2-aminobenzothiazoles with alkynyl carboxylic acids to 1,4-benzothiazines.

A new ring expansion of 2-aminobenzothiazoles with alkynyl carboxylic acids was developed, which allows for one-pot synthesis of 1,4-benzothiazines in moderate to excellent yields. The cascade reaction was achieved through decarboxylative coupling, nucleophilic ring-opening reaction and intramolecular hydroamination process.

Oxidative tandem nitrosation/cyclization of N-aryl enamines with nitromethane toward 3-(trifluoromethyl)quinoxalines.

A novel one-pot strategy for the synthesis of 3-trifluoromethylquinoxalines from N-aryl enamines and nitromethane was developed. The tandem reaction is achieved through nitrosation of alkenes, tautomerization and cyclization, which can be applicable to a wide range of enamines with excellent functional group tolerance and afford quinoxalines in moderate to good yields.

FeCl3-promoted carboxamidation and cyclization of aryl isonitriles with formamides toward phenanthridine-6-carboxamides.

An iron-promoted tandem carboxamidation and cyclization between aryl isonitriles and formamides has been developed. The one-pot strategy can be applied to a wide range of 2-isocyanobiphenyls and formamides with excellent functional group tolerance for the synthesis of phenanthridine-6-carboxamides in moderate to excellent yields.

Synthesis of 6-(trifluoromethyl)phenanthridines via palladium-catalyzed tandem Suzuki/C-H arylation reactions.

A palladium-catalyzed tandem Suzuki/C-H arylation reaction of N-aryltrifluoroacetimidoyl chlorides with arylboronic acids has been developed. A variety of 6-(trifluoromethyl)phenanthridines were prepared in moderate to excellent yields from N-(2-bromophenyl)trifluoroacetimidoyl chlorides which can be conveniently prepared from 2-bromoaniline derivatives.

Palladium-catalyzed iodine-mediated electrophilic annulation of 2-(1-alkynyl)biphenyls with disulfides.

A palladium-catalyzed, iodine-mediated electrophilic annulation between 2-(1-alkynyl)biphenyl and disulfide has been developed. With the combination of PdCl(2) and I(2), a variety of 2-(1-alkynyl)biphenyls underwent electrophilic annulations with various disulfides successfully to afford the corresponding 9-sulfenyl phenanthrenes in moderate to excellent yields.

The characterization of SaPIN2b, a plant trichome-localized proteinase inhibitor from Solanum americanum.

Proteinase inhibitors play an important role in plant resistance of insects and pathogens. In this study, we characterized the serine proteinase inhibitor SaPIN2b, which is constitutively expressed in Solanum americanum trichomes and contains two conserved motifs of the proteinase inhibitor II (PIN2) family. The recombinant SaPIN2b (rSaPIN2b), which was expressed in Escherichia coli, was demonstrated to be a potent proteinase inhibitor against a panel of serine proteinases, including subtilisin A, chymotrypsin and trypsin. Moreover, rSaPIN2b also effectively inhibited the proteinase activities of midgut trypsin-like proteinases that were extracted from the devastating pest Helicoverpa armigera. Furthermore, the overexpression of SaPIN2b in transgenic tobacco plants resulted in enhanced resistance against H. armigera. Taken together, our results demonstrated that SaPIN2b is a potent serine proteinase inhibitor that may act as a protective protein in plant defense against insect attacks.

The nightshade proteinase inhibitor IIb gene is constitutively expressed in glandular trichomes.

The best known property of plant proteinase inhibitor II (PIN2) genes is their wound-inducible expression in leaves and constitutive expression in flowers. Here we show by promoter analysis in transgenic plants and in situ reverse transcription-PCR (RT-PCR) analysis that SaPIN2b, a member of the PIN2 gene family of nightshade (Solanum americanum), is also constitutively expressed in glandular trichomes. SaPIN2b promoter and its deletions were cloned and fused upstream of beta-glucuronidase (GUS) to transform the nightshade and tobacco (Nicotiana tabacum) plants. Histochemical staining assays indicated that SaPIN2b:GUS was expressed constitutively in glandular trichomes, predominantly in the gland cells, of both transgenic nightshade and tobacco plants. Constitutive expression of SaPIN2b in glandular trichomes was further confirmed by liquid phase in situ RT-PCR analysis of nightshade leaves. Deletion analysis from the 5' end of the SaPIN2b promoter revealed that separate regulatory elements control SaPIN2b expression in gland cells and stalk cells of glandular trichomes. Fluorometric GUS assays showed that SaPIN2b:GUS expression was significantly increased in transgenic plant leaves after mechanical wounding or methyl jasmonate treatment. The SaPIN2b promoter sequence contains six MYB-binding motifs and an L1 box that are involved in trichome differentiation and development. Overexpression of SaPIN2b in tobacco resulted in a significant increase in glandular trichome density and promotion of trichome branching. These results suggest that, as well as being an induced defensive protein of the well-known PIN2 family, SaPIN2b could also play roles in trichome-based defense by functioning as a constitutive component of trichome chemical defense and/or by regulating the development of glandular trichomes.