7133-30-4Relevant academic research and scientific papers
Stereochemistry of Decarbalkoxylation of Cyclic Geminal Diesters Effected by Water and Lithium Chloride in Me2SO
Krapcho, A. Paul,Weimaster, John F.
, p. 4105 - 4111 (2007/10/02)
The stereochemical consequences of the decarbalkoxylation of cyclic geminal diesters by LiCl-H2O-Me2SO have been examined.The norbornene diester 13 and the norbornane diester 16 lead predominantly to the exoesters 14 and 17, respectively.The 2-methylcyclohexane diester 22 leads to esters containing more cis (23) than trans (24) isomer.The diesters 19,25, and 28 lead to nearly equal amounts of the cis and trans esters.In these latter cases,the enolates generated from the esters (via LDA) are protonated in a nonstereoselective fashion on quenching with water.This is suggestive of an enolate intermediate in the decarbalkoxylation reaction.The implications of these sterochemical results are discussed.
Stereochemistry of Alkylation of Carboxylic Acid Salt and Ester α Anions Derived from Cyclic Systems.
Krapcho, A.Paul,Dundulis, Edward A.
, p. 3236 - 3245 (2007/10/02)
A stereochemical study of the alkylation of α-lithiated carboxylate salts and esters has been performed.The α anions derived from the bicyclic acids exo-1, endo-1, and 7 (R=H) and the esters 4 and 7 (R=CH3) yield predominantly exo alkylation.As an example, the α anion derived from ester 7 (R=CH3) on treatment with CH3I yields exo-8 (R=R'=CH3) and endo-9 (R=R'=CH3) in a 97:3 ratio, a highly stereoselective reaction.Addition of TMEDA to the reactions involving the α anions derived from exo- or endo-1 did not change the stereochemical alkylation results.The α anions derived from the substituted cyclohexanecarboxylic acids 10, 13, 16, 19, or 22 (where R=H in each case) on methylation yield more axial methylation (axial/equatorial ratios of 0.4-2.7) than the α anions derived from the methyl esters corresponding to these acids.The α anions from the esters yield predominantly equatorial methylated products (e/a ratios varying from 4 to 9).The reasons for the different stereochemical results are discussed.
