Activemethylenecompounds are selectively monoalkylated with alkyl halides in benzene using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a base. Selectivity of monoalkylation decreases when the reaction is carried out in a polar solvent. Ethyl acetoacetate is O-acylated with acyl halides in the presence of DBU in acetonitrile to give the (E)-enol esters stereoselectively.
Stereochemical imperative in enzymic decarboxylations. Stereochemical course of the decarboxylation catalyzed by acetoacetate decarboxylase
作者:J. David Rozzell、Steven A. Benner
DOI:10.1021/ja00329a051
日期:1984.8
explanation, also noted by Hanson and Roses2 If all modern enzymes catalyzing a certain type of reaction evolved from a common ancestral enzyme displaying a particular stereochemicalpreference, a common preference in all modern enzymes might reflect the conservation of the original preference during the evolutionary process. This pair of explanations is merely a molecular example of a ptoblem frequently