Quinolizinium-3-olates

The conversion of 1-hydroxyquinolizinium bromide (187 R = R = H, X = Br) into three quinolizinium-l-olate derivatives (186) has been achieved as follows (i) Treatment with aqueous sodium carbonate gives the hydrated betaine (186 R = R = H) as a yellow solid (ii) brief reaction with hot dilute nitric acid gives red needles of the 4-bromo-2-nitro derivative (186 Ri = NO2, R = Br) and (iii) prolonged reaction with hot dilute nitric acid gives the dinitro derivative (186 R = R = NO2). 1-Hydroxyquinolizinium nitrate (187 R = R = H, X = NO2) and dilute nitric acid give the 2-nitro derivative(186 R = NO2, R = H). Betaine 186(R = Me, R = H) has been detected in aqueous solutions of l-hydroxy-2-methylquinolizinium bromide (187 R = Me. R = H). ° ... 

Compound 287, which is obtained from 7V-carbethoxymethyl-2-methyl-pyridinium bromide and diethyl mesoxalate, undergoes base-catalyzed cyclization to betaine 288 which is readily converted to the quinolizinium-3-olate 286 (R = COjEt, = COjH). Decarboxylation of this compound (286 R = COjEt, R = CO2H) by cupric oxide and quinoline at 180-190 C gives the unsubstituted betaine (286 R = R = Quinolizinium-3-... 

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