-7 c, R= C, H, dilithiated nature of 1 la is substantiated by its chemical reactions and by its 13C NMR spectrum. Reaction of 1 la with methyl iodide gave the dimethylated derivative 12a in 90% isolated yield. The 13C NMR spectrum of 1 la in hexamethylphosphoric triamide (HMPA) showed signals at 156.7, 70.0, 54.0, 39.3, 31.7, and 30.7 ppm, assigned respectively to C-1, C-2,(3-5, C-3, C-4, and C-6, consistent with a symmetrical dilithiated ...