Investigation of synthetic routes towards, and reactions of, 2,3-disubstituted-1, 4-dioxans

• Main Author: Pearson, Ronald George
• Published: University of Surrey 1959
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.751538

Attempted syntheses of the stereoisomeric 2,3-dicarboxy-1,4-dioxans have been made, using methods adapted from the preparation of ethers, and also by substitution of the chlorine atoms in trans-2,5-dichloro-1,4-dioxan. The former method involved the Williamson type of ether synthesis, and also the use of silver oxide (Purdie's method). This method was also applied in the attempted preparation of 2,3-diphenyl-1,4-dioxan, the cis- and trans- isomers of which are known. From the complex mixture of products from the chlorinations of trans-2,3-ethylenedioxy-l,4-dioxan have been isolated both di(2-chloroethyl) oxalate and ethylene oxalate. This is readily accounted for by the assumption that the chlorination leads to trans-2,3-dichloro-2,3-ethylenedioxy-1,4-dioxan, which then undergoes a rearrangement reaction analogous to that already observed with a-chloro-ethers. A third expected rearrangement product, 1,2-dichloroethane was not isolated. It has been shown that the rearrangement, in the present instance, is a thermal one, and it is unlikely that the intermediate, trans-2,3-dichloro-2,3-ethylenedioxy-l,4-dioxan, will be capable of isolation. Bromination of the ethylenedioxy-dioxan, by means of N-bromosuccinimide, afforded di(2- bromoethyl) oxalate only. The oxalates were compared directly (m.p., mixed m.p., infra-red absorption spectra) with authentic esters prepared for the purpose by alternative procedures. The structure of a product, hitherto uninvestigated, from the interaction of trons-2,3-dichloro-1,4-dioxan and diethyl (+)-tartrate, has been limited to three possibilities.