ACETALS AND THIOACETALS FROM THIOGLYCOLALDEHYDE: SOME OXIDATION PRODUCTS

Article abstract of DOI:10.1016/0008-6215(82)84002-0

Thiodiglycolaldehyde (2,2'-thiobisacetaldehyde, 1a) reacted severally with methanol, ethanol, and 2-propanol to give mixtures variously of thiodiglycolaldehyde bis(dialkyl acetals) (3a,b), cis-2,6-dialkoxy-1,4-oxathianes (5b-d), and trans-2,6-dialkoxy-1,4-oxathianes (7a-c).Thiodiglycolaldehyde bis(di-isopropyl acetal) (3c) was not formed in the reaction of 1a and 2-propanol, but 3c was obtained after bromoacetaldehyde di-isopropyl acetal was treated with sodium sulfide.The stereoisomers corresponding to 2,6-dimethoxy-1,4-oxathiane (5b, 7a) were obtained from the acyclic dimethyl acetal 3a.The reaction between 1a and thiols in acid media have been studied.With ethanethiol, thiodiglycolaldehyde bis(diethyl dithioacetal) was the only product, but a mixture of thiodiglycolaldehyde bis(di-tert-butyl dithio-acetal), cis-2,6-bis(tert-butylthio)-1,4-dithiane, and trans-2,6-bis(tert-butylthio)-1,4-dithiane was obtained from 2-methyl-2-propanethiol.On oxidation to sulfones of the stereoisomers of 2,6-dialkoxy-1,4-oxathiane and 2,6-bis(alkylthio)-1,4-dioxane with hydrogen peroxide, the configurations were retained, but the stereoisomers of 2,6-bis(tert-butylthio)-1,4-dithiane were transformed into the same oxidation product.