Uncatalyzed, green aza-Michael addition of amines to dimethyl maleate

A New Approach Utilizing Aza-Michael Addition for Hydrolysis-Resistance Non-Ionic Waterborne Polyester

This work first synthesized a series of linear polyesters by step-growth polycondensation, then an amino-terminated hydrophilic polyether was grafted to the polyester as side-chains through aza-Michael addition to prepare a self-dispersible, non-ionic waterborne comb-like polyester (NWCPE). In contrast to traditional functionalization methods that usually require harsh reaction conditions and complex catalysts, the aza-Michael addition proceeds efficiently at room temperature without a catalyst. In this facile and mild way, the NWCPE samples with number-average molecular weight (Mn) of about 8000 g mol−1 were obtained. All dispersions showed excellent storage stability, reflected by no delamination observed after 6 months of storage. The NWCPE dispersion displayed better hydrolysis resistance than an ionic waterborne polyester, as was indicated by a more slight change in pH value and Mn after a period of storage. In addition, the film obtained after the NWCPE dispersion was cross-linked with the curing agent, it exhibited good water resistance, adhesion, and mechanical properties.

Synthesis of N-(Anthracen-9-ylmethyl)-N-methyl-2-(phenylsulfonyl)ethanamine via Microwave Green Synthesis Method: X-ray Characterization, DFT and Hirshfeld Analysis

N-(Anthracen-9-ylmethyl)-N-methyl-2-(phenylsulfonyl)ethanamine 3 has been synthesized via the aza-Michael addition approach by reaction of the corresponding amine with the vinyl sulfone derivative under microwave conditions. The structure of the aza-Michael product 3 is elucidated by X-ray crystallography. The study of molecular packing by employing the Hirshfeld analysis indicates that the percentages of O…H, C…H and H…H contacts are 16.8%, 34.1% and 48.6%, respectively, where the O...H hydrogen bonds have the characteristics of short and strong contacts while the C...H contacts are considered weak. Density functional theory (DFT) investigations show that the aza-Michael product 3 is polar with a net dipole moment of 5.2315 debye.

Cascade aza-Michael Addition-Cyclizations; Toward Renewable and Multifunctional Carboxylic Acids for Melt-Polycondensation

Although the aza-Michael addition reaction on various unsaturated (di-)carboxylic acids and esters of, for example, itaconic acid, is well-known, the consecutive cyclization reaction has not received much attention in literature. The products of this aza-Michael cascade reaction, being mono- or di-carboxylic acid or ester functionalized N-alkyl-pyrrolidone structures, prove interesting for melt-polycondensation reactions as they exhibit excellent stability at elevated temperatures. In other words, this reaction is a toolbox for the generation of renewable monomers and, in turn, polymers with tunable physiological properties. Therefore, this work provides an overview of the state-of-the-art of the cascade aza-Michael addition-cyclization reactions on biobased unsaturated acids and esters, and their use in polymerization reactions. Furthermore, we extend this overview with the cascade aza-Michael addition-cyclization reaction of trans-trimethyl aconitate with di-amines to form a tetra-functional N-alkyl-bis-(pyrrolidone dimethylcarboxylate), which exhibits excellent thermal stability and could effectively be used as monomer in polycondensation reactions. Importantly, the aza-Michael addition reaction between primary amines and trans-trimethyl aconitate can be considered a click-reaction; it proceeds quantitatively within minutes under ambient conditions and follows the principles of green chemistry.

Chemoselective aza-Michael addition of indoles to 2-aroyl-1,3-diarylenones

A total of 20 examples of 2-[(1 H-indol-1-yl)(aryl)methyl]-1,3-diphenylpropane-1,3-diones were efficiently synthesized by the aza-Michael addition at the N1 position of indoles with 2-aroyl-1,3-diarylenones at room temperature in the presence of potassium hydroxide. The salient features of this protocol are no transition-metal catalysts, mild conditions, high chemoselectivity, high atom economy, high yields, and a simple work-up procedure.

Diastereoselective auxiliary- and catalyst-controlled intramolecular aza-Michael reaction for the elaboration of enantioenriched 3-substituted isoindolinones. Application to the synthesis of a new pazinaclone analogue

A new asymmetric organocatalyzed intramolecular aza-Michael reaction by means of both a chiral auxiliary and a catalyst for stereocontrol is reported for the synthesis of optically active isoindolinones. A selected cinchoninium salt was used as phase-transfer catalyst in combination with a chiral nucleophile, a Michael acceptor and a base to provide 3-substituted isoindolinones in good yields and diastereomeric excesses. This methodology was applied to the asymmetric synthesis of a new pazinaclone analogue which is of interest in the field of benzodiazepine-receptor agonists.

Facile preparation of stereochemistry-controllable biobased poly(butylene maleate-co-butylene fumarate) unsaturated copolyesters: a chemoselective polymer platform for versatile functionalization via aza-Michael addition

Biobased stereochemistry-controllable poly(butylene maleate-co-butylene fumarate) unsaturated copolyesters were facilely prepared as a chemoselective polymer platform for versatile functionalization via aza-Michael addition.

Regioselective 1,4-conjugate aza-Michael addition of dienones with benzotriazole

The regioselective 1,4-conjugate aza-Michael addition of dienones with benzotriazole catalyzed by potassium acetate is described. A series of 3-(benzotriazol-1-yl)-1,5-diarylpent-4-en-1-ones were efficiently synthesized under mild conditions. This protocol has advantages of transition-metal free catalyst, high yield and high regioselectivity.

Synthesis of thermo- and photo-responsive polysiloxanes with tunable phase separationviaaza-Michael addition

Two kinds of thermo- and photo-dual-responsive polysiloxanes were synthesized through a facile, effective, and catalyst-free aza-Michael addition.

Three-component reactions of isocyanoacetates, amines and 3-formylchromones initiated by an unexpected aza-Michael addition

We present herein a new mode of three-component reactions between isocyanoacetates, amines and 3-formylchromones. Mechanistic and DFT studies reveals that this Ag-catalyzed process is initiated by a facile aza-Michael addition.

Aza-Michael Mono-addition Using Acidic Alumina under Solventless Conditions

Aza-Michael reactions between primary aliphatic and aromatic amines and various Michael acceptors have been performed under environmentally-friendly solventless conditions using acidic alumina as a heterogeneous catalyst to selectively obtain the corresponding mono-adducts in high yields. Ethyl acrylate was the main acceptor used, although others such as acrylonitrile, methyl acrylate and acrylamide were also utilized successfully. Bi-functional amines also gave the mono-adducts in good to excellent yields. Such compounds can serve as intermediates for the synthesis of anti-cancer and antibiotic drugs.

Facile synthesis of unsaturated polyester-based double-network gels via chemoselective cross-linking using Michael addition and subsequent UV-initiated radical polymerization

Michael addition and UV-initiated radical polymerization of vinyl monomers were used for a one-pot synthesis of polyester-based double-network (DN) gels by chemoselective cross-linking at room temperature.