Chemistry of acetylenic ethers 104 Thermal rearrangement of 1‐alkynyl 2‐alkynyl sulfides in the presence of dialkylamines or dialkylphosphines. A new type of thio‐claisen rearrangement

Abstract
1‐Alkynyl 2‐alkynyl sulfides, R1CCS‐CH2CCR2, 1, rearrange at room temperature (if R2 = H) or upon heating (if R2 = alkyl). The thioketenes, H2CCC(R2)‐C(R1)CS, 2, presumed to be formed can be trapped by secondary amines, or‐in some cases‐by dialkylphosphines. Depending upon the nature of the substituents R1 and R2 and upon the solvent, allenic thioamides, H2CCC(R2)‐CH(R1)C(S)NR32, 3, conjugated dienic thioamides, H2CCHC(R2)C(R1)C(S)NR32, 4, thiophene derivatives, 5, or mixtures of these types of compounds, are formed.