Theoretical studies on the activation mechanism involving bifunctional tertiary amine–thioureas and isatylidene malononitriles

Abstract

DFT studies on the activation mechanism of the Michael addition reactions containing bifunctional tertiary amine–thioureas and isatylidene malononitriles have been performed at the B3LYP/6-311++G(d,p)//B3LYP/6-31G(d) level of theory.

Unveiling Mechanism of a Quinine-Squaramide Catalyzed Enantioselective Aza-Friedel–Crafts Reaction between Cyclic Trifluoromethyl Ketimine and Naphthol: A DFT Study

“…Recently, we reported the reaction mechanism of an asymmetric conjugate addition of dimethyl phosphites to isatylidene malononitriles catalyzed by bifunctional tertiary amine−thiourea. 24 As a continuation of our interests in investigating the mechanism of organocatalytic asymmetric reactions, herein we report the mechanisms of the quininesquaramide catalyzed aza-Friedel−Crafts (aza-F−C) reaction between cyclic trifluoromethyl ketimine and naphthol (Scheme 1). 25…”

Asymmetric Epoxidation of Alkylidenemalononitriles: Key Step for One-Pot Approach to Enantioenriched 3-Substituted Piperazin-2-ones

“…On the basis of experimental data, a plausible transition state model for the oxa-Michael step of the nucleophilic epoxidation is illustrated in Figure . The alkylidene­malono­nitrile is activated and oriented by a H-bonding network of the thiourea NH and the OH bonds . The OH group of the CHP is expected to be strongly engaged in H-bonding interaction with the basic quinuclidine nitrogen.…”

Asymmetric epoxidation of electron-deficient olefins and synthetic applications

“…16 However, synthetic approaches to differently substituted 1,2-dicarbonyl compounds are usually step intensive and typically involve redox approaches. Other synthetic approaches have been reported to circumvent this limitation; for example, Antoniotti et al reported the There are many reports that describe one-pot procedures to obtain quinoxalines from different starting materials, such as 1,2-diols, 19 alkynes 20 or arylallenes. 21 However, all these procedures are suspect to involve the in situ formation of diketone followed by condensation with o-phenylenediamine, since all of them need oxidative conditions and the use of organometallic catalysts, such as ruthenium or gold.…”

“…20 The first one is limited to symmetrically substituted pyrazines and sometimes instability of α-amino aldehydes intermediates to certain conditions limits the scope of the reaction. The latter shares the same main limitation as quinoxaline-synthesis procedures, i.e.…”