Hydroxymethylation of Rhodanine

摘要

Rhodanine in alcohol solution reacts with formaldehyde aqueous solution to form 3-hydroxymethylrhodanine. In the presence of triethylamine occurred also bis-hydroxymethylation at 5 position of the thiazolidine ring, but we failed to isolate the 3,5,5-trishydroxymethyl derivative in an individual form. The treatment of crude rhodanine 3,5,5-trishydroxymethyl derivative with benzaldehyde in boron trifluoride etherate leads to thioxo-8-phenyl-7,9-dioxa-1-thia-3-azaspiro decan-4-one. The dissolution of the latter in aqueous alkali followed by neutralization with acid gives 5-sulfanyl-2-phenyl-1,3-dioxane-5-carboxylic acid.