55790-72-2Relevant academic research and scientific papers
Metal Coordination Controlled and Bifunctional H-Bonded Catalysis in Stereoselective Intramolecular Aldol Cyclizations toward Carbocyclic Tertiary β-Ketols
Chen, Bin,Berger, Gilles,Hanessian, Stephen
supporting information, p. 2631 - 2636 (2017/05/19)
The principle of bifunctional catalysis is shown in the highly regio- and stereoselective intramolecular aldolization of 2-methyl-1,3-cyclopentanedione, C2-substituted with a methyl ethyl ketone group, to provide [3.2.1]-bicyclooctanol diones in the presence of catalytic amounts of either LiBr and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). Mechanistic investigations corroborated by DFT calculations show that LiBr engages in a bifunctional coordination of two carbonyl moieties and leads to the preorganization of the reactive enolate intermediate for a base-mediated intramolecular aldol cyclization. On the other hand, TBD catalysis of the triketone substrate proceeds through a bifunctional H-bonded mechanism to give the same aldol product as the major diastereomer. The LiBr and TBD-catalyzed highly stereocontrolled intramolecular aldol cyclizations can be extended to other di- and triketones to give carbocyclic and carbobicyclic products as single diastereomers.
Evaluating β-amino acids as enantioselective organocatalysts of the Hajos-Parrish-Eder-Sauer-Wiechert reaction
Davies, Stephen G.,Russell, Angela J.,Sheppard, Ruth L.,Smith, Andrew D.,Thomson, James E.
, p. 3190 - 3200 (2008/03/14)
A systematic study of the effect of substitution within the β-amino acid framework indicates that both β2- and β3- amino acids catalyse the Hajos-Parrish-Eder-Sauer-Wiechert reaction with poor to reasonable levels of enantioselectivity. These results led to the evaluation of the conformationally constrained β-amino acid (1R,2S)-cispentacin, which catalyses the Hajos-Parrish-Eder-Sauer-Wiechert reaction with comparable or higher levels of enantioselectivity to l-proline. The Royal Society of Chemistry.
