One-pot synthesis of novel chitosan-salicylaldehyde polymer composites for ammonia sensing.

Chitosan (Chs)-salicylaldehyde (Sal) polymer derivatives were formed via the reaction of Chs-Sal with zinc oxide nanoparticles (ZnO NPs) and beta-cyclodextrin (β-CD). These polymers were synthesized through inclusion with β-CD and doping with ZnO NPs to give pseudopolyrotaxane and Chs-Sal/ZnO NPs composite, respectively, for low-temperature detection and sensing of NH vapors as great significance in environmental control and human health. Additionally, the polymer (Chs-Sal/β-CD/ZnO NPs) was prepared via the insertion of generated composite (Chs-Sal/ZnO NPs) through β-cyclodextrin ring.

1,3-Dipolar Cycloaddition of 3-Chromonyl-Substituted Glycine Imino Esters with Arylidenes and in situ Diastereodivergent via Retrocycloaddition.

1,3-Dipolar cycloaddition through in situ generation of azomethine ylide provides a straightforward and critically important sustainable approach for access to diverse pyrrolidine chemical space. Herein, we developed a metal-free AcOH-activated 1,3-dipolar cycloaddition protocol that permits the synthesis of uncommon pyrrolidine cycloadducts with excellent diastereoselectivity. The challenging substrates of 3-formylchromone, glycine ester.

Crystal structure and Hirshfeld surface analysis of -[()-(2-hy-droxy-phen-yl)methyl-idene]aniline -oxide.

The conformation of the title compound, CHNO, is partially determined by a strong, intra-molecular O-H⋯O hydrogen bond. The crystal packing consists of strongly corrugated layers parallel to the plane and associated through C-H⋯π(ring) inter-actions. A Hirshfeld surface analysis of the crystal structure indicates that the most significant contributions to the crystal packing are from H⋯H (44.

Nitro-Substituted Benzaldehydes in the Generation of Azomethine Ylides and Retro-1,3-Dipolar Cycloadditions.

1,3-Dipolar cycloaddition of 2- and 3-nitrobenzaldehydes with 2-aminomethylpyridine and ethyl (2)-2-cyano-3-(4-nitrophenyl)prop-2-enoate yielded -cycloadducts as the sole products under various reaction conditions. Fortuitously, 4-nitrobenzaldehyde behaved differently in three- and four-component cascades to produce a mixture of - and '-cycloadducts. This reaction is solvent- and temperature-dependent, and consequently, both the - and '-cycloadducts were synthesized in an excellent regio-, stereo-, and chemoselective fashion.

A facile palladium catalysed 3-component cascade route to functionalised isoquinolinones and isoquinolines.

Palladium catalysed three component cascade process, involving coupling of 2-iodobenzoates, -benzaldehydes, or acetophenones with substituted allenes and ammonium tartrate as an ammonium surrogate, provides a novel and facile route to substituted functionalised isoquinolinones and isoquinolines in good yields.

Stereoselective Pd(0) catalysed five component cascade synthesis of complex Z,Z-bisallylamines.

Catalytic 5-component cascade chemistry provides an effective stereo- and regioselective route to novel multi-functional Z,Z-bisallylamines. The process, which is capable of considerable further extension, utilises ammonium tartrate as a novel ammonia source which avoids the use of ammonia gas or aqueous ammonia.

Exploiting adamantane as a versatile organic tecton: multicomponent catalytic cascade reactions.

3- And 9-component Pd(0) catalysed assembly of allenes, aryl iodides and N-nucleophiles with concomitant installation of trisubstituted Z-alkenes is readily achieved.

Useful dual Diels-Alder behavior of 2-azetidinone-tethered aryl imines as azadienophiles or azadienes: a beta-lactam-based stereocontrolled access to optically pure highly functionalized indolizidine systems.

Imines derived from 4-oxoazetidine-2-carbaldehydes have been found to be versatile Diels-Alder reagents in that they exhibit two reactivity patterns. 2-Azetidinone-tethered imines undergo diastereoselective reaction with Danishefsky's diene in the presence of different Lewis acids. The effect of the amount of catalyst on the conversion rate as well as on the product ratio has been studied.

Efficient entry to highly functionalized beta-lactams by regio- and stereoselective 1,3-dipolar cycloaddition reaction of 2-azetidinone-tethered nitrones. Synthetic applications.

Racemic as well as optically pure 2-azetidinone-tethered nitrones, both cyclic and acyclic, were smoothly prepared from 4-oxoazetidine-2-carbaldehydes. The regio- and diastereoselectivities of the intermolecular 1,3-dipolar cycloaddition reactions of 2-azetidinone-tethered nitrones with substituted alkenes and alkynes were investigated. 2-Azetidinone-tethered nitrones on reacting with various dipolarophiles yielded isoxazolinyl-, isoxazolidinyl-, or fused polycyclic-beta-lactams, exhibiting good regio- and facial stereoselectivity in the most of the cases.

Stereoselective Synthesis of 3-Substituted 4-(Formyloxy)-2-azetidinones by the Unusual Baeyer-Villiger Reaction of beta-Lactam Aldehydes. Scope and Synthetic Applications.

The Baeyer-Villiger oxidation of 4-formyl-beta-lactams 1with m-CPBA gave 4-(formyloxy) beta-lactams 2 in a simple, efficient, and totally stereoselective process. This reaction is one of the scarce examples of the preferred migration of a carbon moiety in an aliphatic aldehyde. The influence of the substituents at N1 and C3 of the four-membered ring in the Baeyer-Villiger rearrangement has been studied.