Improvement of chemical stability of conjugated dienes by chlorine substitution

T. Narumi*, T. Nishizawa, T. Imai, R. Kyan, H. Taniguchi, K. Sato, N. Mase

Tetrahedron, 2018, 74 (45) 6527-6533.

Conjugated systems have versatile utilities in various fields including organic synthesis, pharmaceutical development, and material science. Such systems take advantage of their properties, which include their unique reactivity, relatively rigid structures, and low HOMO-LUMO gap energies. Their utility and the handling of conjugated systems however are both limited by excessively high photosensitivity and reactivity. We now report a novel molecular approach to the improvement of the chemical stability of the acyclic conjugated system against the photolysis and oxidation reactions simply by the introduction of a chlorine atom into the conjugated system. Systematic studies of substrates with various substituents reveal that the improved chemical stability is based on the additive effects of the steric and electronic properties of the chlorine atom substituent.