113863-99-3Relevant academic research and scientific papers
Unsaturated Carboxylic Acid Dienolates. Reaction with Substituted Cyclohexanones and Unsubstituted Cycloalkanones. Regio- and Stereoselectivity
Ballester, Pablo,Costa, Antonio,Garcia-Raso, Angel,Mestres, Ramon
, p. 21 - 32 (2007/10/02)
Regio- and stereo-selectivities for the reaction of lithium dienolates derived from crotonic and dimethylacrylic acids with substituted cyclohexanones (4)-(6) are found to depend on reaction time and temperature. α-Adducts resulting from equatorial attack predominate after a short time at -70 deg C, but axial approach and γ-addition are favoured by longer reaction time and higher temperature.Inversion of axial/equatorial stereoselectivity is observed for some cyclohexanones.For unsubstituted cycloalkanones, regioselectivity is dependent on ring size.This effect can be explained on the basis of Brown's "I-strain" rationalization.For C5-C12 ketones, γ-adducts are found when reactions are carried out above room temperature, but at 0 deg C, C5, C6, and C12 cycloalkanones yield α-isomers whereas mesocyclic ketones afford γ-isomers.
UNSATURATED CARBOXYLIC ACID DIENOLATES. ADDITION TO SUBSTITUTED CYCLOHEXANONES. INVERTED KINETIC AND THERMODYNAMIC STEREOSELECTIVITIES.
Ballester, P.,Costa, A.,Garcia-Raso, A.,Mestres, R.
, p. 3853 - 3856 (2007/10/02)
Addition of the lithium dienolate derived from crotonic acid to monosubstituted cyclohexanones occurs through the α and γ carbon atoms of the dienolate in the cold and on heating, respectively.For any regioselectivity, equatorial approach is found under kinetic conditions, but equilibration favours products from axial attack and selectivity may be inverted.
