Reductive Generation of Aldehyde Metal Enolate from Ketene. A One-Flask Process to 1,1,2-and 1,2,2-Trisubstituted Dihydronaphthalenes from 1- and 2-Naphthalenecarboxylates

Successive treatment of 2,6-di-fert-buty1-4-(methoxypheny1)-1- and -2-naphthalenecarboxylates (BHAesters) (1, 2) with organolithium in THE, lithium triethylborohydride in refluxing THE, methyl iodide-HMPA, and finally sodium borohydride in MeOH provided regioand stereoselectively 1,1,2- and 1,2,2-trisubstituted dihydronaphthalenes (3, 4), respectively, in good yields. This one-flask process is constituted from a sequence of five reactions involving reductive generation of aldehyde metal enolate from ketene as a key step.