Bridgehead enolates: substitution and asymmetric desymmetrization of small bridged carbonyl compounds by lithium amide bases.
[reaction: see text] Contrary to expectations, a number of bridged carbonyl compounds undergo facile bridgehead metalation with lithium amide bases. Diketone, lactone, lactam, and imide functions are all demonstrated to participate in this type of "bridgehead enolate" chemistry, leading to a range of substituted products. Meso compounds can also be desymmetrized in very high ee by asymmetric bridgehead metalation.
GlaxoSmithKline, Department of Medicinal Chemistry, Neurology CEDD, The Frythe, Hertfordshire AL6 9AR, UK.
Gerard M P
GM
Giblin
Douglas T
DT
Kirk
Lee
L
Mitchell
Nigel S
NS
Simpkins