title: Theoretical studies on the intramolecular cyclization of 2,4,6-t-Bu3C6H2P=C: and effects of conjugation between the P=C and aromatic moieties.
abstract: The intramolecular C-H insertion of the Mes*-substituted phosphanylidenecarbene [Mes*P=C:] (Mes* = 2,4,6-t-Bu3C6H2) and physicochemical properties of the cyclized product, 6,8-di-tert-butyl-3,4-dihydro-4,4-dimethyl-1-phosphanaphthalene were studied based on ab initio calculations. Whereas the alternative Fritsch-Buttenberg-Wiechell-type rearrangement requires almost no activation energy, the intramolecular cyclization needs an activation energy of 12.3 kcal/mol at the MP2(full)/6-31G(d) condition. DFT calculations supported that the optimized structure of the cyclization product of Mes*P=C: suggests remarkable conjugation effects between the nearly coplanar P=C skeleton and the aryl moiety.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Aoba, Sendai 980-8578, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Yoshifuji
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Aoba, Sendai 980-8578, Japan ; Department of Applied Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8552, Japan.
authors.forename: Shigekazu
authors.initials: S
authors.lastname: Ito
keywords: 3,4-dihydro-1-phosphanaphthalene; intramolecular cyclization; organophosphorus; phosphanylidenecarbene; steric protection; theoretical calculation