A Potassium tert-butoxide in dimethylformamide. B: Potassium carbonate in N- methylpyrrolidone. C: Potassium carbonate in dimethylformamide. The reaction and workup were performed as described in the Experimental Section.'Yield of recrystallized, pure substance with the R and R'given. The C, H, N elemental analyses of all products except entry 26 and 28 gave values within 0.3% of those calculated. dSee Table 111. eAfter ball- ...