Abstract:

There is a great interest in the synthesis of substituted tetrahydrofurans, because they are present in many biological activity compounds. THF compounds can be obtained by cyclofunctionalization of homoallylic alcohols. Many electrophiles have been used, such as halogens, thallium(III), mercury(II), selenium, etc. The iodocyclization of homoallylic alcohols with terminal double bonds leads to the formation of oxetanes. This happens because the 5-endo-trig cyclization is not favored for this type of substrate. An alternative protocol was developed by our group. The use of hypervalent iodine with a catalytic amount of molecular iodine facilitates the formation of tetrahydrofurans rings from homoallylic alcohols. The proposed mechanism (Scheme 1) consists mainly in the oxidative displacement of iodine from alkyl iodides and the ring expansion of cyclic ethers having an iodoalkyl substituent. In previous work, the reaction was explored with tertiary alcohols. In this study, we expanded the scope of the reaction for primary and secondary alcohols.