14367-06-7Relevant academic research and scientific papers
A Comparative Study of Solid State and Solution Aldol Addition Reactions of the Lithium Enolate of Methyl 3,3-Dimethylbutanoate: Stereochemistry and Mechanistic Implications
Wei, Yen,Bakthavatchalam, R.
, p. 2373 - 2390 (2007/10/02)
We report the first systematic study of the solid state aldol addition reactions of the lithium enolate of methyl 3,3-dimethylbutanoate with various aliphatic or aromatic, achiral or chiral, solid or liquid aldehydes, in comparison with the same reactions performed in tetrahydrofuran (THF) solution.The diastereoselection of the solid state reactions in all the cases was found to be essentially identical to that of the solution reations.At low temperatures ( -20 deg C), both the solid state and the solution reactions are kinetically selective with the syn:anti ratios of approximately 50:50, except for the reactions involving sterically small aldehydes.Decreasing the bulkiness of the aldehydes from pivalaldehyde to acetaldehyde resulted in changes of the syn:anti ratio from 42:58 to 90:10.At higher temperatures, the stereoselection of both the solid state and the solution reactions is thermodynamically controlled, giving predominately anti isomers.The solid state reactions generally afforded low yields and low conversions of the aldehydes.Increasing the reaction time or temperature had little effect on the yields of the solid state reactions.The stereochemical outcomes can be interpreted satisfactorily using the Zimmerman-Traxler-Dubois transition state models.The results suggest that the reacting species and transition states are involved in both the solid state and the solution reactions under our experimental conditions.
Dehydrative Decarboxylation of 2,3-Disubstituted 3-Hydroxycarboxylic Acids with Dimethylformamide Acetals - Mechanistic Studies and Preparative Applicability
Mulzer, Johann,Bruentrup, Gisela
, p. 2057 - 2075 (2007/10/02)
Dimethylformamide dimethylacetal (2a) converts the threo-3-hydroxycarboxylic acids 4 smoothly into the (E)/(Z)-olefins 7/6 only if R2 is an aryl or vinyl substituent.Althougt the reaction exhibits a distinct (E)-selectivity it cannot be considered as a stereo-controlled olefin synthesis.If R2 is alkyl, 2a generates the methyl esters 10 from 4.The erythro-acids 5 react with 2a to give 43 - 95percent of >98percent sterically pure 7.As the key tranformation on the multistep way from 4/5 to 6/7 the fragmentation of the zwitterionic intermediate 11/20 is postulated.
