Chemistry of acetylenic ethers 94 : addition of carbonyl dichloride to 1-alkynyl sulfides and 1-alkynyl ethers

1-Alkynyl sulfides and 1-alkynyl ethers of the type R-CC-Y-R' (R = H or alkyl, R' = alkyl and Y = O or S) were converted into ß-alkyl-thio- and ß-alkoxy-ß-chloro-acrylic chlorides R'Y-CClCR-CO-Cl by addition of carbonyl dichloride (phosgene). The cis-isomers are formed initially [Cl and (COCl) cis], but partial isomerization occurs during work-up. Configurations were determined by comparison of the NMR data with those of several derivatives of acrylic acid. Relative addition rates have been determined in competition experiments. The mechanism of the reaction is discussed.