Products Cited in Publications Worldwide Chiral Cobalt(III) Tris(1,2-diamine) Catalysts That Incorporate Nitrogenous Base Containing Anions for the Bifunctional Activation of Nucleophiles and Electrophiles in Enantioselective Addition Reactions

Chiral Cobalt(III) Tris(1,2-diamine) Catalysts That Incorporate Nitrogenous Base Containing Anions for the Bifunctional Activation of Nucleophiles and Electrophiles in Enantioselective Addition Reactions

Connor Q. Kabes; Reagan F. Lucas; Jack H. Gunn; John A. Gladysz

DOI:

Abstract

The lipophilic diastereomeric cobalt complexes Λ or Δ-[Co((S,S)-dpen)3]3+ 2Cl–BArf– (Λ or Δ-(S,S)-23+ 2Cl–BArf–; dpen/BArf– = 1,2-diphenylethylenediamine/B(3,5-C6H3(CF3)2)4–) catalyze a number of enantioselective C–H bond addition reactions in the presence of aliphatic tertiary amines, but pyridine and N,N-dimethylaniline are much less effective. However, when these bases are incorporated into counter anions (4–) as in Λ or Δ-(S,S)-23+4–Cl–BArf–, highly enantioselective bifunctional catalysts can be realized. Salts of nicotinates, isonicotinates, related sulfonates, and N,N-dimethylaminobenzoate are effective. The 6-chloronicotinate salt gives slower rates and lower ee values, and the 6-aminonicotinate salt gives faster rates and higher ee values. The 6-methyl, 2-methoxy, and unsubstituted analogs afford intermediate results. The 6-aminonicotinate catalyst is applied to additions of dimethyl malonate to 14 aryl-substituted nitroolefins and additions of 6 1,3-dicarbonyl compounds to di-t-butyl azodicarboxylate, with average yields/ee values of 90%/85% and 94%/77%, respectively. The authors are unaware of other ionic catalysts for which Brønsted bases have been productively incorporated into the anions, which are seldom if ever purposefully functionalized in any manner.

Keywords

cobalt ; 1,2-diamines ; smart anions ; task specific anions ; hydrogen bonding ; bifunctional catalysts ; enantioselective catalysis ; Michael additions

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A23672716635-95-398%

(1R,2R)-rel-1,2-Diphenylethane-1,2-diamine

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