7131-66-0Relevant academic research and scientific papers
Structural investigations into the retro-Diels-alder reaction. Experimental and theoretical studies
Birney, David,Lim, Tang Kuan,Koh, Joanne H. P.,Pool, Brett R.,White, Jonathan M.
, p. 5091 - 5099 (2002)
The manifestations of the retro-Diels Alder reaction in the ground-state structures of a range of cyclopentadiene and cyclohexadiene cycloadducts 9-15 have been investigated by a combination of techniques. These include low-temperature X-ray crystallography, density functional calculations (B3LYP/6-31G(d,p)) on both the ground states and transition states, and the measurement of 13C-13C coupling constants. We have found that the carbon - carbon bonds (labeled bonds a and b), which break in the rDA, are longer in the cycloadducts 9-15 than in their corresponding saturated analogues 9s-15s, which cannot undergo the rDA reaction. The degree of carbon - carbon bond lengthening appears to be related to the reactivity of the cycloadduct, thus the more reactive benzoquinone cycloadducts 5b and 13 have longer carbon - carbon bonds. Those cycloadducts 14 and 15 which are predicted to undergo asynchronous reactions show differing degrees of carbon - carbon bond lengthening, reflecting the differing degrees of bond breaking at the calculated transition states for the rDA.
Enantiomeric separation of bicyclo[2.2.2]octane-based 2-amino-3-carboxylic acids on macrocyclic glycopeptide chiral stationary phases
Pataj, Zoltan,Ilisz, Istvan,Grecso, Nora,Palko, Marta,Fueloep, Ferenc,Armstrong, Daniel W.,Peter, Antal
, p. 200 - 208 (2014/04/17)
Direct high-performance liquid chromatographic (HPLC) separation of four bicyclo[2.2.2]octane based 2-amino-3-carboxylic acid enantiomers were developed on chiral stationary phases (CSPs) containing different macrocyclic glycopeptide antibiotic selectors.
Decarbonylative cross-coupling of cyclic anhydrides: Introducing stereochemistry at an sp3 carbon in the cross-coupling event
O'Brien, Erin M.,Bercot, Eric A.,Rovis, Tomislav
, p. 10498 - 10499 (2007/10/03)
Treatment of cyclic anhydrides with stoichiometric amounts of nickel-neocuproine complex generates alkylcarboxylato-nickelalactones upon extrusion of CO. These metalacycles undergo cross-coupling with arylzinc reagents. The generated CO is sequestered in situ by a nickel-dppb complex. The overall sequence effects a secondary sp3(electrophile)-sp2(nucleophile) cross-coupling and allows for control of stereochemistry during the bond-forming event. Copyright
Highly Enantioselective Ring Opening of Cyclic Meso-Anhydrides to Isopropyl Hemiesters with Ti-TADDOLates: An Alternative to Hydrolytic Enzymes?
Jaeschke, Georg,Seebach, Dieter
, p. 1190 - 1197 (2007/10/03)
The Lewis acid mediated transfer of an alkoxide ligand from the chiral ligand sphere of Ti - TADDOLate (1) to cyclic meso anhydrides to afford the corresponding hemiesters is described. By using this method a variety of structurally different anhydrides can be converted to isopropyl hemiesters with high enantioselectivities (enantiomer ratios up to 99:1). We have also investigated Lewis acidic titanium complexes, which differ from 1 in the chiral ligand or the alkoxide ligand that is transferred. Finally, a catalytic version, which allows the substoichiometric use of Ti- TADDOLate in the presence of stoichiometric amounts of Al(Oi-Pr)3, is presented.
