Flash vacuum pyrolysis of acetylenic esters: A mechanistic study

Products from flash vacuum pyrolysis of eleven acetylenic esters are reported in this study. The mechanism of their pyrolysis is proposed based on the products isolated. These reveal a combination of two main mechanistic approaches. Esters with β-hydrogens favor a retro-ene reaction via a six-membered transition state, the absence of such β-hydrogen leads to a carbene intermediate followed by insertion and cyclization.