| Popis: |
The preparation, structure, and reactivity of methyl 3,3-bis(4-dimethylamino) pyridinium-1-yl) propenoate dichloride (1) are discussed. 1,2,3,3-Tetrakis(4-(dimethylamino) pyridinium-1-yl) cyclopropene tetrachloride (2) was converted to 1 with formic or acetic acid in methanol. A mechanism for the conversion of 2 to 1 is suggested. Hydrolysis of 1 under basic conditions gave 3,3-bis(4-(dimethylamino) pyridinium-1-yl) propenoic acid (3), which has a pK a of 2. The X-ray structure of 1 shows that the pyridinium rings are both twisted with respect to the double bond; the resulting high steric hindrance prevent Diels-Alder reactions with dienes despite the electrophilic nature of the system |
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