N-Benzoylamides of 2,2,6,6-tetramethylpiperidine are not ortholithiated by organolithium compds. but instead undergo nucleophilic addn. of the organolithium compd. to the arom. ring in the manner of a conjugate addn. The resulting dearomatized enolates may be protonated or alkylated, and yield substituted cyclohexadienes in yields of up to 76%. Deprotection of the piperidine ring is possible under
Isochroman-3-ones via site-selective ring opening of benzocyclobutenones promoted by lithium tetramethylpiperidide and reaction with aromatic aldehydes
In the presence of Li-TMP and an aromatic aldehyde, benzocyclobutenone undergoes an unusual heterolytic C(1)C(4) bondfission, and subsequent reaction with the aldehyde gives, after acidic workup, isochroman-3-one in high yield.