Template effect in the synthesis of formyl derivatives of benzothiacrown compounds

The condensation of 3,4-bis(2-haloethoxy)benzaldehydes with acyclic α,ω-alkanedithiols in the presence of alkali metal carbonates in dry ethanol, DMF, MeCN and their mixtures with water gives formyl derivatives of benzothiacrown compounds in high yields. The best results are attained when the radius of the hydrated metal cation fits to the crown ether cavity. In the case of Cs⁺, high yields were observed for crown ethers of any size and composition; this can be explained by a specific template effect of this cation. The influence of the nature of the leaving group in 3,4-bis(2-haloethoxy)benzaldehydes was established for reactions with dithiols containing no ether oxygen atoms. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya No. 11, pp. 1881–1886, November, 2000.