Nucleophilicity Vs. Basicity In The Reaction Of Sodium T-Butoxide With B-Stannylketones

ALICIA CHOPA,; ANA PAULA MURRAY

ORGANOMETALLICS

American Chemical Society

Año: 2001 vol. 20 p. 1476 - 1478

0276-7333

Summary: The reaction of 3-stannyl-1,2,3-triphenyl- and 3-stannyl-1,3-diphenyl-2-methylpropanones with sodium tert-butoxide in either t-BuOH or dimethyl sulfoxide (DMSO) as solvent leads to elimination and/or substitution products. The composition of the product mixtures depends essentially on the nature of the ligands attached to the tin atom, on the solvent, and also on the nature of the substituent on C-2. Thus, â-(triphenyl), â-(bromodiphenyl), and â-(trichlorostannyl) ketones undergo an exclusive elimination reaction leading to an unsaturated ketone in good to high yields (72%-96%) both in t-BuOH and in DMSO. In the latter the reactions lead to higher yields in shorter times. On the other hand, â-(trimethylstannyl) ketones lead to mixtures of olefins and substitution products in t-BuOH and exclusively to substitution products in DMSO (96%-98%). Stereochemical results suggest that the elimination reactions proceed through an (E1cB)R mechanism.R mechanism.â-(trimethylstannyl) ketones lead to mixtures of olefins and substitution products in t-BuOH and exclusively to substitution products in DMSO (96%-98%). Stereochemical results suggest that the elimination reactions proceed through an (E1cB)R mechanism.R mechanism.â-(triphenyl), â-(bromodiphenyl), and â-(trichlorostannyl) ketones undergo an exclusive elimination reaction leading to an unsaturated ketone in good to high yields (72%-96%) both in t-BuOH and in DMSO. In the latter the reactions lead to higher yields in shorter times. On the other hand, â-(trimethylstannyl) ketones lead to mixtures of olefins and substitution products in t-BuOH and exclusively to substitution products in DMSO (96%-98%). Stereochemical results suggest that the elimination reactions proceed through an (E1cB)R mechanism.R mechanism.â-(trimethylstannyl) ketones lead to mixtures of olefins and substitution products in t-BuOH and exclusively to substitution products in DMSO (96%-98%). Stereochemical results suggest that the elimination reactions proceed through an (E1cB)R mechanism.R mechanism.â-(trichlorostannyl) ketones undergo an exclusive elimination reaction leading to an unsaturated ketone in good to high yields (72%-96%) both in t-BuOH and in DMSO. In the latter the reactions lead to higher yields in shorter times. On the other hand, â-(trimethylstannyl) ketones lead to mixtures of olefins and substitution products in t-BuOH and exclusively to substitution products in DMSO (96%-98%). Stereochemical results suggest that the elimination reactions proceed through an (E1cB)R mechanism.R mechanism.â-(trimethylstannyl) ketones lead to mixtures of olefins and substitution products in t-BuOH and exclusively to substitution products in DMSO (96%-98%). Stereochemical results suggest that the elimination reactions proceed through an (E1cB)R mechanism.R mechanism.-96%) both in t-BuOH and in DMSO. In the latter the reactions lead to higher yields in shorter times. On the other hand, â-(trimethylstannyl) ketones lead to mixtures of olefins and substitution products in t-BuOH and exclusively to substitution products in DMSO (96%-98%). Stereochemical results suggest that the elimination reactions proceed through an (E1cB)R mechanism.R mechanism.â-(trimethylstannyl) ketones lead to mixtures of olefins and substitution products in t-BuOH and exclusively to substitution products in DMSO (96%-98%). Stereochemical results suggest that the elimination reactions proceed through an (E1cB)R mechanism.R mechanism.-98%). Stereochemical results suggest that the elimination reactions proceed through an (E1cB)R mechanism.R mechanism.