Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

Abstract

The scope of applications of dialkyl dicyanofumarates and maleates as highly functionalized electron-deficient dipolarophiles, dienophiles and Michael acceptors is summarized. The importance for the studies on reaction mechanisms of cycloadditions is demonstrated. Multistep reactions with 1,2-diamines and β-aminoalcohols leading to diverse five- and six-membered heterocycles are discussed. Applications of dialkyl dicyanofumarates as oxidizing agents in the syntheses of disulfides and diselenides are described. The reactions with metallocenes leading to charge-transfer complexes with magnetic properties are also presented.

Experimental and Computational Studies on Stepwise [3+2]‐Cycloadditions of Diaryldiazomethanes with Electron‐Deficient Dimethyl (E)‐ and (Z)‐2,3‐Dicyanobutenedioates

“…In a series of recent studies, electron‐deficient dimethyl ( E )‐ and ( Z )‐2,3‐dicyanobutenedioates 1 [dicyanofumarate ( E )‐ 1 and dicyanomaleate ( Z )‐ 1 ] were described as superior components of 32CAs with TACs such as thiocarbonyl S ‐methanides, azomethine ylides, and diazoalkanes . Whereas the reaction with diazomethane ( 2a ) afforded mixtures of pyrazole derivatives and stereoisomeric cyclopropanes, reactions with 2‐diazopropane ( 2b ) led to exclusive formation of the corresponding cyclopropanes in a stereoselective manner (Scheme ).…”

“…dicyanomaleate (Z)-1] were described as superior components of 32CAs with TACs such as thiocarbonyl S-methanides, azomethine ylides, and diazoalkanes. [4] Whereas the reaction with diazomethane (2a) afforded mixtures of pyrazole derivatives and stereoisomeric cyclopropanes, [5] reactions with 2-diazopropane (2b) led to exclusive formation of the corresponding cyclopropanes in a stereoselective manner [6] (Scheme 1). 9-Diazofluorene (2c) and diphenyldiazomethane (2d) are easily available and both compounds are widely applied in reactions with diverse ethylene derivatives.…”

Exploring the Photochemical Reactivity of Multifunctional Photocaged Dienes in Continuous Flow

“…A suitable TA is a dienophile forming a more stable DA adduct than maleimide, and hence will not undergo a retroDA in the temperature range as used in here. A variety of TAs are available ranging from thietene 1,1‐dioxide to morpholine or tetracyanoethylene (TCE) . Herein, TCE was selected as trapping agent.…”

Pull‐Pull Alkenes in the Aza‐Michael Reaction

“…Really, the electron-deficient dialkyl dicyanofumarates 27 -symmetrically substituted alkenes bearing two alkoxycarbonyl and two cyano groups -react readily with nitrogen nucleophilesammonia, primary and secondary amines, hydrazine and hydrazides as well as N,N-, N,O-and N,Sbinucleophiles. [30] All these reactions proceed accord-ing to addition -HCN elimination mechanism leading to push-pull alkenes or heterocycles. For example, when dialkyl dicyanofumarates (E)-27 were treated with one equivalent of diverse aliphatic and aromatic primary or secondary amines at room temperature, corresponding enamines bearing two alkoxycarbonyl and one cyano groups were obtained as a single product in good to high yields.…”

“…For example, dialkyl dicyanofumarates and maleates are attractive Michael acceptors having numerous applications for the multistep assembly of linear and heterocyclic compounds. Really, the electron‐deficient dialkyl dicyanofumarates 27 – symmetrically substituted alkenes bearing two alkoxycarbonyl and two cyano groups – react readily with nitrogen nucleophiles – ammonia, primary and secondary amines, hydrazine and hydrazides as well as N,N‐, N,O‐ and N,S‐binucleophiles [30] . All these reactions proceed according to addition – HCN elimination mechanism leading to push‐pull alkenes or heterocycles.…”