Chemistry of acetylenic ethers XVII: The reactions of some ethoxyethynylcarbinols with mercaptans and thio‐acids

Abstract
The addition of ethyl mercaptan to 1‐ethoxy‐3‐methylbut‐1‐yn‐3‐ol (V) under the influence of peroxides yielded 1‐ethoxy‐2‐ethylmercaptobut‐1‐ene‐3‐ol (VI) in high yield (reaction scheme A). This substance could be rearranged to 2‐ethylmercapto‐3‐methylcrotonaldehyde (VII) (reaction scheme B). The same reaction took place with other mercaptans.The addition of ethyl mercaptan to 1‐(1‐hydroxycyclohexyl)‐2‐ethoxyethyne (XV) and 1‐(1‐hydroxycyclopentyl)‐2‐ethoxyethyne (XVI) under the same conditions yielded 2‐cyclohexylidene‐2‐ethylmercaptoacetaldehyde (XVIII) and 2‐cyclopentylidene‐2‐ethylmercaptoacetaldehyde (XXII) after rearrangement (reaction scheme D).Other thioenol ether compounds were prepared (reaction schemes C and D) starting from the aldehydes VII, XVIII and XXII.Addition of thiobenzoic acid to 1‐ethoxy‐3‐methylbut‐1‐yn‐3‐ol (V) proceeded by a different (probably ionic) mechanism and yielded ‐ after rearrangement and saponification ‐ β,β‐dimethylacrylic acid (reaction scheme E).