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TitleStudies in the cycloproparene series: Cycloaddition reactions of diarylmethylidenecycloproparenes
Publication TypeJournal Article
Year of Publication2001
AuthorsHalton, B., Kay A.J., McNichols A.T., Stang P.J., Apeloig Y., Boese R., Maulitz A.H., and Haumann T.
Pagination8 - 31
Date Published2001
ISSN14246376 (ISSN)
Keywordsalkadiene, analytic method, article, benzene, benzindanone, benzofuran derivative, calculation, carbon, chemical bond, chemical procedures, chemical reaction, crystallography, cycloaddition, cyclobutanaphthalene, cyclobutarene, cycloproparene, diphenyliodonium salt, fluorine, hydrogen, indanone derivative, methyl group, naphthalene derivative, norcaradiene, Oxygen, polycyclic aromatic hydrocarbon derivative, propane, propelladiene, pyrone derivative, quantum chemistry, structure analysis, substitution reaction, sulfur, theory, unclassified drug, X ray analysis
AbstractDiarylmethylidenecyclopropanaphthalenes 4b-d add diphenylisobenzofuran (DPIBF) and α-pyrone across the exocyclic double bond to give ring expanded products 11b-d and 13b-d that result from subsequent relief of ring strain in the non-isolable spirocyclic intermediates 10 and 12, respectively. The benzene homologues 3b and 3c add DPIBF across the bridge bond to give the norcaradiene adducts 19b and 19c. These observations match expectation based upon the loss of aromaticity in the arene moiety caused by addition to the bridge bond. The cycloadditions have been studied also by ab initio quantum mechanical calculations at the MP2/6-31G(d)//HF/6-31G(d) and MP3 levels of theory. With acetylenic(phenyl)-iodonium triflates 14 formal [2+2] cycloaddition to the exocyclic π bond of 4b-d leads to the 2,3-disubstituted naphthalenes 18b-d. The structures of the iodonium salt 18d and the bridge adduct 19b are confirmed from structure determination by X-ray crystallographic methods.

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