68613-82-1Relevant academic research and scientific papers
Photochemistry of Bichromophoric Molecules. Intramolecular Excited-State Interactions in the cis- and trans-Decalin-Connected Aryl Olefins: 7-Methylene-4bβ-methyl-4bβ,5,6,7,8,8aβ,9,10-octahydrophenanthrene and Its 8aα Isomer
Pallmer, Michael,Morrison, Harry
, p. 798 - 803 (2007/10/02)
The photochemistry and photophysics of the title compounds (1,2) are reported.The trans-decalin 1 is relatively photoinert but the cis isomer (2) undergoes a singlet-derived, intramolecular, 1,3 photocycloaddition to give 13 (φ = 0.046).It is proposed that 13 is formed via an intramolecular exciplex (Scheme II) as in the acyclic analogue, 6-phenyl-2-hexene (3) , with a rate constant for complexation, kex, equal to 5.4*106 s-1.This is 185-fold slower than kex for 3 and corresponds to a ΔG298 (=8.2 kcal/mol) which can be equated with a requisite half-chair/chair to half-chair/boat isomerization (eq 3).Though neither 1 nor 2 is phosphorescent at 77 K, 2 sensitizes the isomerization of 1-methylcyclohexene to methylenecyclohexane at room temperature in solution.Thus, intermolecular triplet-energy transfer is competitive with intramolecular energy transfer.Compound 13 efficiently (φ = 0.51) photocycloeliminates to give a carbene-derived product, 15.
