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An enantioselective Friedel–Crafts alkylation reaction of pyrroles and indoles with N‐unprotected trifluoromethyl ketimines by use of chiral phosphoric acid provided α‐trifluoromethylated primary amines bearing chiral tetrasubstituted carbon centers in high yields and with high to excellent enantioselectivities. The present reaction is unique to N‐unprotected trifluoromethyl ketimines. No reaction took place with N‐p‐methoxyphenyl (PMP)‐substituted ketimine. Corresponding α‐trifluoromethylated amines were transformed without loss of enantioselectivity. [ABSTRACT FROM AUTHOR]

Abstract: 1,3‐Dipolar cycloadditions (1,3‐DC) between imino esters (as precursors of N‐metallated azomethine ylides) and π‐deficient alkenes are promoted by cooperative asymmetric Lewis acid/Brønsted base catalysis. The components of these catalytic pairs are silver salts derived from enantiopure commercially available BINOL‐based phosphoric acids and Cinchona alkaloids. Chiral phosphoric silver(I) salts promote HOMO raising of in situ formed 1,3‐dipoles, whereas protonated cinchona alkaloids generate a LUMO lowering for the dipolarophiles resulting in a global acceleration of the 1,3‐DC. The best results were obtained with BINOL‐derived silver phosphate and hydrocinchonine. Matching between both cooperative metallo‐ and organocatalyst results in an enhanced enantiomeric excess, superior to that reached by both separate components. NOESY experiments and DFT calculations are compatible with a non‐covalent interaction (hydrogen bond) between both catalysts, which results in close contacts and mutually coupled chiral environments. [ABSTRACT FROM AUTHOR]

Asymmetric synthesis of tetrahydrobenzodiazepines was achieved by transfer hydrogenation of dihydrobenzodiazepines with benzothiazoline having a hydrogen-bonding donor substituent by means of a newly synthesized chiral phosphoric acid. This method was applicable to various racemic dihydrobenzodiazepines to give the corresponding products in good yields with excellent diastereoselectivities and enantioselectivities taking advantage of the dynamic kinetic resolution. Furthermore, the effect of bulky substituent at 3,3′-position on the catalyst and hydrogen-bonding donor substituent on benzothiazoline was fully elucidated by the theoretical study. [ABSTRACT FROM AUTHOR]

Chiral phosphoric acid catalyzed transfer hydrogenation of ketimines derived from propiophenone derivatives and reductive amination of alkyl ethyl ketone derivatives were extensively examined in the presence of two representative hydrogen donors. The excellent enantioselective transfer hydrogenation was achieved by use of benzothiazoline as a hydrogen donor. The theoretical studies elucidated that the unsymmetrical structure of benzothiazoline plays an important role in high enantioselective hydrogenation. [ABSTRACT FROM AUTHOR]