Intramolecular cyclization of the product of iodo-alkoxylation with 3,4-dihydro-2H-pyrano dimethylacetylene carbinol and with its Csp-substituted derivatives

Abstract

As a result of the research of the reaction of 3,4-dihydro-2H-pyrano-dimethylacetylene carbinol (also with its Csp-substituted derivatives) of iodo-alkylation on clinoptilolite in the presence of (NaK)4CaAl6Si30O72 and crystalline iodine, 3-iodine-2-[(2-methyl-4-organyl-but-3-in-2-yl)oxy]oxane was prepared. This method of preparation of heterocyclic compounds allows the reaction to be carried out in the absence of solvents, which reduces the amount of reagents and allows obtaining a product with high purity and high yield (67.5%). It was established that the latter under the conditions of the Kucherov reaction turn into heterocyclic compounds. Thus, effective regioselective methods for the synthesis of dioxin derivatives have been developed. This fact is probably related and is obviously explained by the intramolecular cyclization of the resulting intermediate-ketohydroxyester, i.e. tandem hydrolysis of C–I and hydration of CC bonds of the reaction products. The yield of 2-benzyl-3,3-dimethylhexahydro-4aH-piran[2,3-b][1,4]dioxin-2-ol is higher than that of structural analogues. It should also be noted that the synthesized compounds have an increased reactivity, and are rich in nucleophilic centers. Based on experimental data, it was established that the compounds obtained in this way are stable and do not undergo hydrolysis. Some physicochemical properties of the synthesized compounds were given, their composition and structure were confirmed by elemental analysis data, and all synthesized compounds were identified by IR and NMR spectroscopy.