Photolysis and thermolysis of (iodomethyl)cyclopropane: Rapid ring opening of cyclopropylcarbinyl via heavy‐atom tunneling?

UV photolysis of (iodomethyl)cyclopropane yielded 3-buten-1-yl instead cyclopropylcarbinyl, the expected product photolytic C-I bond cleavage. This result suggests that ring opening intermediate cyclopropylcarbinyl even at T ~10 K proceeds too fast to be measured via this technique. finding is in agreement with earlier theoretical studies which predicted rapid decay heavy-atom tunneling. In an attempt rule out potential secondary photochemistry enabling opening, flash vacuum thermolysis experiments were also performed. However, those resulted butadiene as sole product, both its thermodynamically favored trans- and higher-energy gauche-conformation.