Axially Chiral Imidodiphosphoric Acid Catalyst for Asymmetric Sulfoxidation Reaction: Insights on Asymmetric Induction

Abstract

Insights into chiral induction for an asymmetric sulfoxidation reaction involving a single oxygen atom transfer are gained through analyzing the stereocontrolling transition states. The fitting of the substrate into the chiral cavity of a new class of imidodiphosphoric Brønsted acids, as well as weak CH⋅⋅⋅π and CH⋅⋅⋅O noncovalent interactions, are identified as responsible for the observed chiral induction.

Role of keto–enol tautomerization in a chiral phosphoric acid catalyzed asymmetric thiocarboxylysis of meso-epoxide: a DFT study

“…This is presumably because of the more favorable steric arrangement of the reactants (epoxide and thiobenzoic acid tautomers) inside the catalytic cavity as well as the presence of stronger noncovalent interaction in 2b compared to that of 2a. [31][32][33] The catalyst·product complex obtained from TS b (3b; ΔG rel = −19.2 kcal mol −1 ) demonstrates a thermodynamically more stable spacial arrangement inside the chiral cavity than that obtained from TS a (3a; ΔG rel = −16.7 kcal mol −1 ). The pre-transition state ( preTS) complex, 2b, then undergoes a nucleophilic ring opening reaction with simultaneous dual proton transfers assisted by the phosphoric acid group of the catalyst via a concerted asynchronous transition state (eight membered cyclic TS).…”

“…It is interesting to note that the coordination of the thiol form of the acid to 1 results in a termolecular complex 2a (ΔG rel = 7.4 kcal mol −1 ) which has a higher energy than that of the termolecular complex 2b (ΔG rel = −0.2 kcal mol −1 ) resulting from the coordination of its thione tautomer. 31 It was found that non-classical hydrogen bonds such as C-H⋯π and C-H⋯O interactions are important to influence the observed stereoselectivity. The presence of non-classical hydrogen bonds (C-H⋯O interactions) in these prereacting complexes has been verified by Mayer bond order analysis (0.03) and AIM analysis (ρ bcp of the order of 0.02 a.u.).…”

Understanding the Reactivity and Selectivity of Fluxional Chiral DMAP‐Catalyzed Kinetic Resolutions of Axially Chiral Biaryls

“…This is corroborated by quantitative AIM‐based analyses . Thus, overall, the mechanism of this reaction is dictated by the subtle interplay of a number of non‐covalent interactions, which is reminiscent of enzyme‐based catalysis …”

The activation strain model and molecular orbital theory

“…Conveniently, there is no special computer code required to perform activation strain analyses: all necessary quantities can be computed using any of the regular quantum‐chemical software packages available. As a result, the activation strain model has been applied by various research groups, on a range of chemical processes, such as nucleophilic substitution, cycloaddition, oxidative addition, isomerization, and many other processes from organic and organometallic chemistry.…”