85977-96-4Relevant academic research and scientific papers
STERIC AND KINETIC EFFECTS OF CHANGING SOLVENT AND REAGENT IN GRIGNARD REACTIONS ON SOME 4-SUBSTITUTED CYCLOHEXANONES
Cianetti, Claudia,Maio, Giorgio Di,Pignatelli, Vito,Tagliatesta, Pietro,Vecchi, Elisabetta,Zeuli, Errico
, p. 657 - 666 (2007/10/02)
The stereochemistry and relative rates of Grignard reactions on some 4R-substituted cyclohexanones (R = tBu, Me, OMe, CO2Me, OCOPh and Cl) have been determined under two separate reaction conditions (MeMgI in C6H6 and MeMgCl in THF).The results of our studies indicate that substrates containing an ester group have a higher reaction order in Grignard reactant than other groups when reactions were carried out in the aromatic solvent.The same is not true for reactions carried out in THF.Both stereochemical product ratios and relative reaction rates are better understood assuming that compounds containing a polar group (OMe and Cl at least) react via a transition state possessing that group in the axial conformation.
A CASE OF STEREOSELECTIVITY CHANGE IN GRIGNARD REACTION COMPETITION EXPERIMENTS
Maio, Giorgio Di,Vecchi, Elisabetta,Zeuli, Errico
, p. 485 - 488 (2007/10/02)
The stereochemical product ratio 2/3 of cis- and trans-1-methyl-2-oxabicyclo-decan-3-ones derived from methyl 3-(2-oxocyclohexyl)propanoate, 1, with MeMgI in C6H6 regularly increase in competition reactions with 4-oxocyclohexanecarboxylic acid methyl ester, 4, as the amount of the last-mentioned compound increases.This effect is related to the total concentration of keto esters in the reaction mixture.Competition experiments were also performed in THF with MeMgCl: no drift in 2/3 ratio was observed.
ALKYLATION OF δ-KETOESTERS : A MECHANISM CHANGE DEPENDING ON CONFORMATIONAL MOBILITY AND SUBSTITUENT EFFECTS ON STEREOSELECTION.
Di Maio, G.,Vecchi, E.,Zeuli, E.
, p. 5211 - 5214 (2007/10/02)
Kinetic evidence shows that the two groups of a δ-ketoester can interact in the transition state of a Grignard reaction.This promotes high stereoselectivity by chiral center far from the ketonic group and produces good correlations between stereoselection and electronic effects of substituents.
