Tetrazolo[1,5-a]pyridine (1) and its angularly and linearly fused benzologues tetrazolo[1,5-a]quinoline (4), tetrazolo[5,1-a]isoquinoline (7), and tetrazolo [1,5-b]isoquinoline (10), respectively, were alkylated by methyl iodide, dimethyl sulfate, trimethyloxonium, and triethyloxonium salts to give mixtures of 1- and 2-alkyl compounds in different ratios. While tetrazoles 1 and 4 afforded mainly 1-alkyl compounds, tetrazole 7 yielded predominantly 2-alkyl compound. Comparison of the linearly (10) and angularly fused (4 and 7) analogues showed that besides steric factors the annelation effect influences also the regioselectivity of these reactions. A satisfactory correlation was found between densities of the MO representations of the lone electron pairs calculated by CNDO/2 and the experimental findings.
ASJC Scopus subject areas
- Organic Chemistry