CYCLOAROMATIZATION OF A NONCONJUGATED POLYENYNE SYSTEM - SYNTHESIS OF5H-BENZO[D]FLUORENO[3,2-B]PYRANS VIA DIRADICALS GENERATED FROM ENYL)BUTAN-1,3-DIYNYL)]PHENYLPENTAN-2,4-DIYN-1-OLS AND TRAPPING EVIDENCE FORTHE 1,2-DIDEHYDROBENZENE DIRADICAL

Authors
MIYAWAKI K SUZUKI R KAWANO T UEDA I
Citation
K. Miyawaki et al., CYCLOAROMATIZATION OF A NONCONJUGATED POLYENYNE SYSTEM - SYNTHESIS OF5H-BENZO[D]FLUORENO[3,2-B]PYRANS VIA DIRADICALS GENERATED FROM ENYL)BUTAN-1,3-DIYNYL)]PHENYLPENTAN-2,4-DIYN-1-OLS AND TRAPPING EVIDENCE FORTHE 1,2-DIDEHYDROBENZENE DIRADICAL, Tetrahedron letters, 38(22), 1997, pp. 3943-3946
Citations number
21
Categorie Soggetti
Chemistry Inorganic & Nuclear
Journal title
Tetrahedron letters → ACNP
ISSN journal
00404039
Volume
38
Issue
22
Year of publication
1997
Pages
3943 - 3946
Database
ISI
SICI code
0040-4039(1997)38:22<3943:COANPS>2.0.ZU;2-B
Abstract
Non-conjugated tetraynes 1 undergo thermal intramolecular cyclization to non-benzenoid diradicals (23) followed by radical cycloaromatizatio n at 25 degrees C to provide 7-dehydro-5H-benzo[d]fluoreno[3,2-b]pyran monoradical(24) and alkyl radicals(25). Hydrogen abstraction of 24 gi ves 5H-benzo[d]fluoreno[3,2-b]pyrans (3) which are converted to 4 by r eaction with 25. On the other hand, 2 gives 5H-fluorenol (5), indicati ng the formation of 1,2-didehydrobenzene diradical intermediates (28 a nd 29). These radicals are trapped as the corresponding Diels-Alder-ty pe products by reaction with an aromatic diene, anthracene. (C) 1997 E lsevier Science Ltd.