Design and Applications of N-tert-Butyl Sulfinyl Squaramide Catalysts

Abstract

A new chiral HBD system, N-tert-butyl sulfinyl squaramide, was designed and synthesized. The core N-tert-butyl sulfinyl squaramide with an 1-aminoindan-2-ol skeleton was found to be an efficient catalyst in the enantioselective Friedel-Crafts alkylation of indoles and acyl phosphonates.

N-tert-Butyl Sulfinyl Squaramide Receptors for Anion Recognition through Assisted tert-Butyl C–H Hydrogen Bonding

“…Also, it has been found that the C–H···O hydrogen-bonding interactions could serve as a key factor in controlling stereoselectivity . Recently, our group developed a novel N - tert -butyl sulfinyl squaramide, in which the N - tert -butyl sulfinyl group enhances the lipophicity and acidity of squaramide . The novel N - tert -butyl sulfinyl squaramide successfully catalyzed the enantioselective Friedel–Crafts alkylations of indoles and acyl phosphonate.…”

DABCO-Catalyzed Michael/Alkylation Cascade Reactions Involving α-Substituted Ammonium Ylides for the Construction of Spirocyclopropyl Oxindoles: Access to the Powerful Chemical Leads against HIV-1

“…3-Halooxindoles with both nucleophilicity and eletrophilicity at the C-3 position have been entailed in many elegant annulation reactions to date, giving various highly substituted spirocyclic oxindoles . On the other hand, α,β-unsaturated acyl phosphonates were proved to be robust electron-deficient olefins and often serve as activated ester surrogates in organic synthesis . Recently, we documented DMAP-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with α,β-unsaturated acyl phosphonates, furnishing a class of spiropyrrolidinyl-2,3′-oxindoles with high efficiency .…”

Chirality Sensing of Molecules with Diverse Functional Groups by Using N‐tert‐Butyl Sulfinyl Squaramide

“…Recently, we developed the hydrogen‐bonding donor compound, N ‐ tert ‐butyl sulfinyl squaramide, in which the N‐tert ‐butyl sulfinyl group serves as a hydrogen‐bond acceptor and enhances the lipophilicity as well as the acidity of the squaramide. In our previous study, we found that N‐tert ‐butyl sulfinyl squaramide has better hydrogen‐bonding donor abilities than traditional squaramide.…”