Conversion of cycloalk-2-enones into 2-methylcycloalkane-1,3-diones—assessment of various Tamao-Fleming procedures and mechanistic insight into the use of the Me3SiMe2Si unit†
Abstract
Conjugate addition of Me3SiMe2SiLi to cycloalk-2-en-1-ones, ketalization, Tamao–Fleming oxidation (Bu4NF, then H2O2, KHCO3), TPAP oxidation and acid hydrolysis generates 2-methyl cycloalkane-1,3-diones. Ketalization is needed in order to prevent addition of Me3Si− to the carbonyl. The pentamethyldisilanyl group has advantages over other silicon units that are used in Tamao–Fleming procedures.