1,3-Cycloalkadiones were prepared by the reaction of l,2-bis(trimethylsiloxy)cycloalkenes with chloromethyl methyl ether followed by treatment of the resulting 2-hydroxy-2-methoxymethyl cycloalkanones with potassium hydrogen sulfate. The first step of the reactions was effectively catalyzed by active zinc reagents prepared from zinc–copper and alkyl iodides.
Ambident Reactivity of Medium-Ring Cycloalkane-1,3-dione Enolates<sup>1</sup>
作者:Glenn S. Thompson、Jerry A. Hirsch
DOI:10.1021/jo971515k
日期:1998.2.1
Cycloalkane-1,3-diones with ring sizes 7-10 have been converted to their enolates and subjected to a variety of ethylation and methylation reagent/solvent systems. The greatest amount of O-alkylation was encountered using ethyl tosylate in HMPA. The O/C alkylation ratios decreased with almost every reagent/solvent system as the ring size was increased. This trend is consistent with greater steric strain in the conjugated enolate resonance contributor, resulting in diminished O-attack as the ring size is increased.