title: Dimerization of indanedioneketene to spiro-oxetanone: a theoretical study.
abstract: Indanedioneketene, a compound resulting from the thermal degradation of the phenyliodonium ylide of lawsone, dimerizes quantitatively to a spiro-oxetanone derivative, a key compound for further transformations. A theoretical electronic structure study of this unusual for alpha-oxoketenes [2 + 2] cyclization reaction both in the gas phase (DFT, MP2) and in dichloromethane solution (DFT), provides support for (a) a single-step, transition-state (involving a four-membered cyclic ring) charge-controlled, concerted mechanism and (b) a [4 + 2] cyclization reaction, not observed but studied theoretically in this study. A parallel study of an open-chain alpha,alpha'-dioxoketene dimerization explains the difference in the stability and reactivity observed experimentally between the cyclic and open-chain products.
authors.affiliation: Laboratory of Applied Quantum Chemistry, Department of Chemistry, POB 135, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece. bakalbas@chem.auth.gr
authors.forename: Evangelos G
authors.initials: EG
authors.lastname: Bakalbassis
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Malamidou-Xenikaki
authors.forename: Spyros
authors.initials: S
authors.lastname: Spyroudis
authors.forename: Sotiris S
authors.initials: SS
authors.lastname: Xantheas
mesh_terms: D003198:Computer Simulation; D003500:Cyclization; D019281:Dimerization; D007189:Indans / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D007783:Lactones / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D007189:Indans; D007659:Ketones; D007783:Lactones; D013141:Spiro Compounds; C518112:indanedioneketene