Enolate Reactions of Bicyclooctan-7-ones

Article abstract of DOI:10.1021/jo00304a020

Under kinetic conditions, the lithium enolate formed from the bicyclo<4.2.0>octan-7-one 3 undergoes reaction with MeI, EtI, and dimethyl disulfide to give 6-substituted compounds 7-9 in 65percent, 43percent, and 70percent yield, respectively, rather than the anticipated 8-substituted isomers.Similarly, fluorination of the silyl enol ether gives the 6-fluoro compound 10 in 40percent yield.Using a TMSCl trapping technique it was shown that kinetic deprotonation takes place at both the 6- and 8-positions in bicyclo<4.2.0>octan-7-ones, whereas the thermodynamic product is the expected 6-enolate.Generation of the enolate from a mixture of 6- and 7-silyl enol ethers (57:43) results in 6- and 8-alkylated products.The kinetic enolate from bicyclo<4.2.0>oct-2-en-7-one is the 7-enol derivative.