Exocyclic Olefinic Maleimides: Synthesis and Application for Stable and Thiol‐Selective Bioconjugation

Michael addition reactions between biological thiols and endocyclic olefinic maleimides are extensively used for site‐specific bioconjugation. The resulting thio‐succinimidyl linkages, however, lack stability because of their susceptibility to thiol exchange. Reported herein is that in contrast to their endocyclic counterparts, exocyclic olefinic maleimides form highly stable thio‐Michael adducts which resist thiol exchange at physiological conditions. A high‐yielding approach for synthesizing a variety of exocyclic olefinic maleimides, by 4‐nitrophenol‐catalyzed solvent‐free Wittig reactions, is reported. Mechanistic studies reveal that the catalyst facilitates the formation of the Wittig ylide intermediate through sequential proton donation and abstraction. Overall, this report details an improved thiol bioconjugation approach, a facile method for synthesizing exocyclic olefinic maleimides, and demonstrates that phenolic compounds can catalyze ylide formation.     

Synthesis of 6H-pyrrolo[3',4':2,3][1,4]diazepino[6,7,1-hi]indole-8,10(7H,9H)-diones using 3-bromo-4-(indol-1-yl)maleimide scaffold

Series of 3-arylalkyl- or 3-alkylamino-4-(indol-1-yl)maleimides and bis(indol-1-yl)maleimides were synthesised. The cyclization of the 3-substituted 4-(indol-1-yl)maleimides under the action of acids resulted in the formation of diazepine[1,4] derivatives with indoline and maleimide nuclei annelated. These compounds readily produced the corresponding indolomaleimidodiazepines[1,4] after dehydrogenation.     

A new mild radical route to 3-substituted maleimides using organoboroles

A new, mild, radical route for the synthesis of 3-substituted maleimides has been developed. This new method incorporates alkene hydroboration, conjugate addition-aminoxylation and TEMPO-H elimination in a one-pot procedure, using cheap, readily available starting materials. A variety of 3-substituted maleimides have been prepared in good to excellent yield.     

Development of a library of N-substituted maleimides for the local functionalization of linear polymer chains

A novel kinetic process was investigated for functionalizing "on-demand" local regions of well-defined linear polystyrene chains. This concept relies on the atom transfer radical copolymerization (ATRP) of functional N-substituted maleimides with styrene. This copolymerization is a controlled radical process, which combines two unique kinetic features: i) all the polymers chains are growing simultaneously and ii) the cross-propagation of the comonomers is highly-favored as compared to homopolymerization. Thus, discrete amounts of N-substituted maleimides (e.g., 1 equiv as compared to initiator) are consumed extremely fast in the copolymerization process and are therefore locally incorporated in narrow regions of the growing polystyrene chains. MALDI-TOF analysis of model copolymers indicated that this kinetic concept is efficient. Although a sequence distribution is observed, well-defined polymer chains having only one or two functional maleimide units per chain were found to be the most abundant species. Furthermore, the position of the functional groups in the polystyrene chains can be kinetically-controlled by adding the N-substituted maleimides at desired times during the course of the polymerization. This method is very versatile and can be applied to a wide variety of N-substituted maleimides. Herein, a library of 20 different maleimides bearing various functional groups (e.g., aromatic moieties, fluorinated groups, hydroxy functions, protected esters, protected amines, light-responsive moieties, fluorophores and biorelevant functions such as short poly(ethylene glycol) segments or biotin moieties) was investigated. In most cases, the functional N-substituted maleimides could be efficiently incorporated in the polystyrene chains.     

Peptide-Catalyzed Stereoselective Conjugate Addition Reaction of Aldehydes to C-Substituted Maleimides

Catalytic stereoselective additions with maleimides are useful one-step reactions to yield chiral succinimides, molecules that are widespread among therapeutically active compounds but challenging to prepare when the maleimide is C-substituted. We present the tripeptide H-Pro-Pro-Asp-NHC₁₂H₂₅ as a catalyst for conjugate addition reactions between aldehydes and C-substituted maleimides to form succinimides with three contiguous stereogenic centers in high yields and stereoselectivities. The peptidic catalyst is so chemoselective that no protecting group is needed at the imide nitrogen of the maleimides. Derivatization of the succinimides was straightforward and provided access to chiral pyrrolidines, lactones, and lactams. Kinetic studies, including a Hammett plot, provided detailed insight into the reaction mechanism.     

Maleimides As a Building Block for the Synthesis of High Performance Polymers

Maleimides are gaining a great deal of attention in both scientific and industrial communities since they can be used in high performance macromolecular systems: thermosets with high temperature stability, self-healing systems, or in click chemistry reactions. After an introduction, this review reports in the first part the different routes to synthesize maleimides. In the second part, this review focuses on the use of maleimides in polymer synthesis, first through nucleophilic reactions, second via cycloaddition to yield remendable systems, and then via radical polymerization. Finally, the industrial availability of maleimides is discussed.     

(S)-1,1-二苯基-2-吡咯啶甲醇催化蒽酮与马来酰亚胺的不对称Diels-Alder反应

研究了(S)-1,1-二苯基-2-吡咯啶甲醇催化蒽酮与马来酰亚胺的不对称D iels-A lder反应,考察了蒽酮与不同N-取代马来酰亚胺的反应。结果表明,在最佳反应条件下化学产率97%,对映选择性44%。     

Synthesis of N-(fluoro phenyl) maleamic acids and N-(fluoro phenyl) maleimides

A series of seven N-(fluoro phenyl) maleamic acids and their N-(fluoro phenyl) maleimides were prepared by the reaction of fluoro phenyl amines ( o-, m-, and p-fluoro, 2.4-, 2.5-difluoro, 2.3.5.6-tetrafluoro and 2.3.4.5.6.-pentafluoro anilines) with maleic anhydride according to substantial modifications made to the reaction conditions used by Searle for the preparation of normal N-aryl maleimides.     

Synthetic transformations of higher terpenoids: XIV. Heterocyclization reactions of 15,16,18-ricarboxylabdadiene. New nitrogen-containing diterpenoids

The oxidation of methyl lambertianate with Jones’ reagent formed the corresponding anhydride which reacted with amines to form N-substituted terpenoid maleimides. New maleimides demonstrated high activity and stereoselectivity in the Diels-Alder reaction with cyclopentadiene. The condensation of the diterpenoid anhydride with hydrazines led to the formation of derivatives of 3,6-dioxo-1,2,3,6-tetrahydropyridazines of labdane type.     

N-取代基马来酰亚胺均聚合研究进展

N-取代基马来酰亚胺聚合物具有良好的热性能,近些年来随着材料性能的要求提高,对这类单体的研究也越来越多,本论文综述了N-取代基马来酰亚胺在自由基、阴离子聚合、配位聚合等方面的均聚合研究进展。     

Synthesis and attempted polymerization of N-arylmaleimides substituted with allylamino or cyclopropylamino groups at 2-position

Several N-substituted chloromaleimides were prepared by dehydrating the corresponding chloromaleamic acids. Treatment of chloromaleimides with allylamine or cyclopropylamine produced N-aryl-2-(allylamino)maleimides and N-aryl-2-(cyclopropylamino)maleimides, respectively. Neither the N-substituted chloromaleimides nor the N-aryl-2-(allylamino) or N-aryl-2-(cyclopropylamino)maleimides polymerized free radically or anionically. The difficulty of achieving good pi-pi overlap and stiric effects at the propagation step prevented the cyclopolymerization of the prepared 1,5-dienes.     

Asymmetric Organocatalytic Addition Reactions of Maleimides: A Promising Approach Towards the Synthesis of Chiral Succinimide Derivatives

Recent progress in asymmetric organocatalysis has led to the development of several asymmetric transformations that employ various substrates. Among these substrates, maleimides have emerged as excellent Michael acceptors, dienophiles, and dipolarophiles. In this Focus Review we highlight the advances in the asymmetric synthesis of succinimide derivatives through asymmetric organocatalytic addition reactions of maleimides.     

A convenient synthesis of 3,4-diaryl(hetaryl)-substituted maleimides and maleic anhydrides

A convenient procedure has been developed for the synthesis of 3,4-diaryl(or hetaryl)maleimides by cross coupling of N-substituted 3,4-dibromomaleimides with aryl(hetaryl)boronic acids in the presence of Pd(Ph₃P)₄ and CsF. The reaction ensures high yields of the products and requires relatively small amount of the catalyst; it can be performed on an enlarged scale. The resulting maleimides are readily converted into the corresponding maleic anhydrides.     

Titrimetric determination of maleinimide and acrylate groups in organic compounds

A simple procedure is proposed for determining the concentration of maleimide and acrylate groups in organic compounds based on the addition of morpholine to the activated double bond by the Michael reaction, followed by the potentiometric titration of the reaction mixture with 1 M HCl in ethanol. The applicability of the method to N-substituted maleimides with aromatic, aliphatic, and oligomeric substituents, as well as to acrylates and acrylonitrile, is verified. It is demonstrated that maleimides and acrylates can be determined simultaneously.     

A new method for the synthesis of functionalized maleimides

An effective route to novel maleimides is described, which involves the reaction of an enamine derived from the addition of a secondary amine to a dialkyl acetylenedicarboxylate with an arylsulfonyl isocyanate. These maleimides in solution indicate dynamic NMR because of restricted rotation around the carbon-nitrogen bond, resulting from conjugation of the side-chain nitrogen with the adjacent α,β-unsaturated ester group.     

One pot synthesis of maleimide and hydantoin by Fe(CO)5 catalyzed [2 + 2 + 1] co-cyclization of acetylene, isocyanate and CO

In the presence of a catalytic amount of Fe(CO)(5), terminal acetylenes, isocyanates and CO undergo [2 + 2 + 1] cyclization to form substituted maleimides and hydantoins; when internal alkynes are used, exclusive maleimide formation is observed. While the maleimides can be obtained as the major products, in up to 90% yield, when the reaction is carried out in CO atmosphere, in absence of CO, the hydantoins are formed in up to 87% yield. Formation of maleimides has been shown to occur via the formation of a ferrole intermediate, whereas the hydantoins are proposed to form through successive insertion of isocyanate into the iron-acetylide bond. All compounds were characterized by spectroscopic methods and molecular structures of some compounds were established by single crystal X-ray diffraction method.     

N-对位取代苯基马来酰亚胺与苯乙烯溶液共聚动力学的研究

以DMF为溶剂 ,采用膨胀计法对N 对位取代苯基马来酰亚胺与苯乙烯的溶液共聚动力学作了系统研究 .其中N 苯基马来酰亚胺与苯乙烯的均相溶液聚合 ,聚合速率方程为Rp=k[I]1/ 2 [M ].同时还测定了四种N 对位取代苯基马来酰亚胺与苯乙烯在DMF中的共聚表观活化能 ,并由此证明四种单体的共聚活性及CTC络合物的存在     

Chiral primary amine thiourea promoted highly enantioselective Michael reactions of isobutylaldehyde with maleimides

Chiral primary amine thiourea catalysts were first successfully applied to promote Michael addition of isobutyraldehyde to maleimides. A variety of N-aryl and N-aliphatic maleimides provided Michael adducts in excellent yields (up to 98%) and enantioselectivities (up to 99% ee) with 5 mol % catalyst.     

Intermediates of radiation-induced polymerisation of maleimides studied by ESR

Radicals produced by radiolysis and photolysis of maleimides (maleimide, N-methylmaleimide, N-ethylmaleimide, N-phenyl-maleimide) in bulk have been identified by ESR spectroscopy. γ-Irradiation of maleimides yields up to five different radicals depending on the type of maleimide. Because of the great linewidth of powder ESR spectra, the hyperfine splittings are determined by means of computer simulation. For N-alkyl maleimides the starting species of polymerisation are formed by abstraction of a H-atom from the alkyl group in radiolysis as well as in photolysis. The structure of the propagating radical shows that polymerisation proceeds via the ethylenic double bond. The detection of maleimide ions makes participation of these ions in polymerisation conceivable. Radiolysis of maleimide and N-phenylmaleimide yields the same type of radicals whereas only ions could be detected after u.v.-irradiation.     

Thermal decomposition of copolymers of styrene and halogenated monomers

Copolymers of 1,2,2,2-tetrachloroethyl esters of unsaturated acids and halogenated N-phenyl maleimides with styrene were pyrolyzed; volatile products were analyzed with a mass spectrometer combined with a gas chromatograph. Hydrogen halide and carbon dioxide in the volatile products were determined during the thermal decomposition of copolymers in glass ampoules; the acyl chloride groups were determined in the residues. The thermal decomposition of copolymers of tetrachloroethyl esters with styrene sets in at ca. 230° by the release of chloral from the copolymer and splitting of some of the CCl bonds in the copolymer. The decomposition of copolymers of styrene with halogenated N-phenyl maleimides starts above 300° by depolymerization of the polystyrene chain sections and by splitting of some of the carbon-halogen bonds. At 310 and 500° for copolymers of tetrachloroethyl esters and at 500° for halogenated N-phenyl maleimides, there is radical dehydrohalogenation of the copolymers, with depolymerization of polystyrene blocks and splitting of carbon-carbon bonds in the main chain.