Design of Brønsted Acid-Assisted Chiral Brønsted Acid Catalyst Bearing a Bis(triflyl)methyl Group for a Mannich-Type Reaction

Abstract

[Structure: see text] A new Brønsted acid-assisted chiral Brønsted (chiral BBA) acid catalyst (1) was developed by substituting a hydroxy group of optically active 1,1'-bi(2-naphthol) with a stronger Brønsted acidic group such as a bis(trifluoromethanesulfonyl)methyl group. The enantioselective Mannich-type reaction of ketene silyl acetals with aldimines catalyzed by (R)-1 in the presence of stoichiometric achiral proton sources gave (S)-beta-amino esters in high yield with moderate to good enantiomeric excesses.

An Effective Method to Introduce Carbon Acid Functionality: 2,2‐Bis(trifluoromethanesulfonyl)ethylation Reaction of Arenes

“…[5,6] The aryl-substituted derivatives, which are depicted as Tf 2 CHAr, may be prepared by a stepwise procedure through the nucleophilic substitution of reactive benzylic halides by NaOS(O)CF 3 and the following a-triflylation of the resulting monosulfone compounds by using tBuLi and Tf 2 O. [7] We also reported that 1,1,3,3-tetrakis(trifluoromethanesulfonyl)propane 1 (Tf 2 CHCH 2 CHTf 2 ) performs as one of the most effective Brønsted acid pre-catalysts for CÀC bond forming reactions using silylated nucleophiles.…”

Stereoselective synthesis and characterization of new enantiomerically pure phosphoric acids

“…21 With our present catalytic system, the addition of methanol showed some positive effect indeed on the stereochemistry of the process; the reaction between 13 and 15 in the presence of a stoichiometric amount of methanol afforded the product in 77% yield and 55% ee (entry 4, Table 2). However, the use of other achiral proton source did not bring any other further improvement (entries 5-7 of Table 2).…”

Organic acids as efficient catalysts for group transfer polymerization of N,N-disubstituted acrylamide with silyl ketene acetal: polymerization mechanism and synthesis of diblock copolymers

“…Thus, the comprehensive study for the GTP of DAA coupled with available organocatalysts and initiator design is still one of the challenging and remaining tasks in GTP chemistry. [42] 1-methoxy-1-(triisopropyl siloxy)-2-methyl-1-propene ( iPr SKA), and 1-methoxy-1-(triphenylsiloxy)-2-methyl-1-propene ( Ph SKA) were synthesized according to previous reports.…”