Cyclodextrins containing an acetone bridge. Synthesis and study as epoxidation catalysts

Abstract

Three cyclodextrine derivatives (6^A,6^D-di-O-(prop-2-one-1,3-dienyl)-α-cyclodextrin (1), 6-O-(prop-2-one-1-yl)-α-cyclodextrin (2) and 6^A,6^D-di-O-(prop-2-one-1,3-dienyl)-β-cyclodextrin (3)) were synthesised and investigated as epoxidation catalysts. The three compounds were synthesised from the corresponding perbenzylated cyclodextrins which were mono- or didebenzylated in the 6-position using Sinaÿ's method. Reaction with NaH and methallyl chloride in the case of 2, or methallyl dichloride in the case of 1 and 3, followed by dihydroxylation, periodate cleavage and protection group removal gave the target compounds. All three compounds catalysed, in the presence of oxone, the epoxidation of a series of alkenes. Epoxidation was compared to the reaction catalysed by simple ketones and inhibition was studied.