Thermal rearrangements of cis-bicyclo[6.2-0]deca-9-enes and a new cope rearrangement

✍ Scribed by Phillip Radlick; William Fenical

• Publisher: Elsevier Science
• Year: 1967
• Tongue: French
• Weight: 222 KB
• Volume: 8
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)89628-3

✦ Synopsis

We wish to report the thermal behavior of the cis-bicyclo[6.2.0]decenes, I-III. 1 The known' thermal rearrangement of bicyclo[3*2.0]hepta-2,6-diene to I II III cycloheptatriene is here shown to be extended to the bicyclic systems above which also possess the condensed cyclobutene moiety. It is also shown that the observed stereospecific reactions are in each case in the theoretical predictions of Woodward and Hoffmann for tions of the type 2n,2u + 4s and 6n + 4n,26. When &-bicyclo[6*2-01 deca-9-ene, I, was heated to direct support of electrocyclic reac-200° for one hour in the vapor phase, a 95% conversion to the known 4 cis.trans-1,3-cyclodecadiene, IV, occurred. This stereoisomer can only result via the predicted3 conrotatory process. The structure of IV was confirmed by its infra-red spectrum, identical in every respect to that previously published, 4 by its catalytic hydrogenation with platinum in ether to cyclodecane and by its nmr spectrum: 5 (3.827 multiplet (21x), 4.627 multiplet (2H), 7.917 multiplet (4H) and 8.687 multiplet (8~)). IV was also found to be quantitatively converted to the &,cis isomer, V, by acetone sensitized irradiation in Pyrex for 72 hours. Similar sensitized photochemical cis-trans isomerizations have been studied in detail by Hammond. 6 --