190143-64-7Relevant articles and documents
Theoretical mechanistic study of the TBD-catalyzed intramolecular aldol reaction of ketoaldehydes
Hammar, Peter,Ghobril, Cynthia,Antheaume, Cyril,Wagner, Alain,Baati, Rachid,Himo, Fahmi
, p. 4728 - 4736 (2010)
(Figure Presented) The intramolecular aldol reaction of acyclic ketoaldehydes catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) is investigated using density functional theory calculations. Compared to the proline-catalyzed aldol reaction, the use of TBD provides a unique and unusual complete switch of product selectivity. Three mechanistic pathways are proposed and evaluated. The calculations provide new insights into the activation mode of bifunctional guanidine catalysts. In the favored mechanism, TBD first catalyzes the enolization of the substrate and then the C-C bond formation through two concerted proton transfers. In addition, the computationally predicted stereochemical outcome of the reaction is in agreement with the experimental findings.
TBD-catalyzed direct 5- and 6-enolexo aldolization of ketoaldehydes
Ghobril, Cynthia,Sabot, Cyrille,Mioskowski, Charles,Baati, Rachid
supporting information; experimental part, p. 4104 - 4108 (2009/05/27)
Treatment of unfunctionalized acyclic ketoaldehydes with a catalytic amount of 1,5,7-triazabicyclo[4.4.0]dec-5-ene induces a direct intramolecular 5- and 6-enolexo aldolization, furnishing 2-ketocyclopentanols and 2-ketocyclohexanols in good-to-excellent yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
REDUCTION OF DELTA 2-ISOXAZOLINES. PART 3: RANEY-NICKEL CATALYZED FORMATION OF beta -HYDROXY KETONES.
Curran
, p. 5826 - 5833 (2007/10/02)
The importance of the beta -hydroxy ketone moiety has led to the development of a wide variety of aldol type methodologies for its construction. A conceptually new approach to these 'aldol adducts' is presented on the basis of left bracket 3 plus 2 right bracket dipolar cycloaddition of in situ generated nitrile oxides and olefins followed by reduction of the resulting DELTA **2-isoxazolines. This approach provides a nice complement of the aldol type reaction. Optimum conditions for the transformation of DELTA **2-isoxazolines to beta -hydroxy ketones use Raney-nickel catalyst, boric acid, 5/1 MeOH/H//2O, and hydrogen gas. Under these mild conditions, 3-methyl-5-n-butyl- DELTA **2-isoxazoline is transformed to 4-hydroxy-2-octanone in high yield. Thus 'directed aldol' type adducts are readily available by selection of the appropriate olefin and nitrile oxide precursor (usually the 1 degree nitro compound).
