Synthesis of 2-(substituted methyl)quinolin-8-ols and their complexation with Sn(II)

Abstract

A new method for the synthesis of 2-(substituted methyl)quinolin-8-ol is described. 2-Methyl-8-methoxyquinoline 3 was prepared as a key building block; lithiation of 3 with LDA and subsequent addition of alkyl halides followed by reaction in 48% HBr afforded the 2-alkylquinolin-8-ols 6a,b. On the other hand, the use of alkanediyl dihalides as the electrophile gave bis(quinolin-8-ol) derivatives containing an alkyl bridge 12. The complexation of 2-alkyl-8-hydroxyquinolines with SnCl₂ in alkaline methanol produced the bis(quinolin-8-ol) complexes 13a,b, whereas in the case of the bis(quinolin-8-ol) derivatives, intractable solids were obtained. The molecular structure of 13b was elucidated by X-ray analysis.