54646-15-0Relevant articles and documents
A Lewis Base Catalysis Approach for the Photoredox Activation of Boronic Acids and Esters
Lima, Fabio,Sharma, Upendra K.,Grunenberg, Lars,Saha, Debasmita,Johannsen, Sandra,Sedelmeier, Joerg,Van der Eycken, Erik V.,Ley, Steven V.
supporting information, p. 15136 - 15140 (2017/11/20)
We report herein the use of a dual catalytic system comprising a Lewis base catalyst such as quinuclidin-3-ol or 4-dimethylaminopyridine and a photoredox catalyst to generate carbon radicals from either boronic acids or esters. This system enabled a wide range of alkyl boronic esters and aryl or alkyl boronic acids to react with electron-deficient olefins via radical addition to efficiently form C?C coupled products in a redox-neutral fashion. The Lewis base catalyst was shown to form a redox-active complex with either the boronic esters or the trimeric form of the boronic acids (boroxines) in solution.
A catalytic enantioselective route to hydroxy-substituted quaternary carbon centers: Resolution of tertiary aldols with a catalytic antibody
List, Benjamin,Shabat, Doron,Zhong, Guofu,Turner, James M.,Li, Anthony,Bui, Tommy,Anderson, James,Lerner, Richard A.,Barbas III, Carlos F.
, p. 7283 - 7291 (2007/10/03)
Aldolase antibody 38C2-catalyzed resolutions of tertiary aldols were studied. Tertiary aldols proved to be very good substrates for antibody catalyzed retro-aldol reactions. The catalytic proficiency, (k(cat)/K(M))/k(uncat), of the antibody for these reactions was on the order of 1010 M-1. A fluorogenic tertiary aldol allowed for the quantitative study of enantiomeric excess as a function of reaction conversion, revealing an E value of ca. 160 in this case. Study of a variety of substrates demonstrated that antibody-catalyzed retro-aldolization provides rapid entry to highly enantiomerically enriched tertiary aldols, typically > 95% ee, containing structurally varied, heteroatom-substituted quaternary carbon centers. The utility of this approach to natural product syntheses has been demonstrated with the syntheses of (+)-frontalin, the side chain of Saframycin H, and formal syntheses of (+)- and (-)-mevalonolactone.
Mechanistic studies of an antibody-catalyzed elimination reaction
Romesberg, Floyd E.,Flanagan, Mark E.,Uno, Tetsuo,Schultz, Peter G.
, p. 5160 - 5167 (2007/10/03)
Catalytic antibody 43D4-3D12, which was generated against the substituted tertiary amine 1, catalyzes the elimination of HF from β- fluoroketone 2. We have cloned and produced the antibody as a chimeric Fab and constructed a model of the active site-substrate complex. Mutagenesis studies of the active site indicate that Glu(H)50 acts as the general base and suggest that Tyr96(L) may also play a role in the elimination reaction. Antibody 43D4-3D12 also efficiently catalyzes the elimination of HBr from substrate 4 by an E2 mechanism, again involving selective abstraction of the proton β-to the nitrophenyl ring by Glu(H)50. The antibody-catalyzed reaction affords predominantly the internal olefins, whereas the major product resulting from the uncatalyzed reaction is the alcohol, which arises from the competing substitution reaction. In addition, antibody 43D43D12 catalyzes an acetal hydrolysis reaction in which Glu(H)50 likely acts as a general acid. These studies point to the Success of this particular hapten design strategy in generating an active site with a desired catalytic functional group. They also illustrate the utility of using related reactions as mechanistic probes of biological catalysis.
Copying nature's mechanism for the decarboxylation of β-keto acids into catalytic antibodies by reactive immunization
Bj?rnestedt, Robert,Zhong, Guofu,Lerner, Richard A.,Barbas III, Carlos F.
, p. 11720 - 11724 (2007/10/03)
Reactive immunization was used to generate catalytic antibodies that use the enamine mechanism common to the natural class I aldolase enzymes. In order to investigate the possibility of exploiting the imine and enamine intermediates programmed into antibo
