Singlet oxygenation of 7-aryl and 7-alkyl-1,3,5-cycloheptatrienes: substituent effects on the product distribution of tropilidene- and nocaradiene-derived endoperoxides

✍ Scribed by Waldemar Adam; Hector Rebollo

• Publisher: Elsevier Science
• Year: 1982
• Tongue: French
• Weight: 278 KB
• Volume: 23
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)85744-5

✦ Synopsis

The N/T ratio, 1. e. the proportion of norcaradlene (u) versus tropilldene (1) endopero xldes in the cycloaddltlon of singlet oxygen with 7-substituted 1,3,5-cycloheptatrlenes, decreases in the order p-C1C6H4 > C6H5 >p-MeOC6H4 and t-Bu > l-Pr > Et > Me, presumably reflecting the ability of these substltuents in promoting the tropllldene to norcaradlene valence isomerization. A long standing problem of mechanistic interest concerns the influence of substltuents on the valence lsomerlzatlon of cycloheptatrlenes. Recent work has dealt with the elucidation of the electronic and sterlc nature of the substltuents by examining the equilibrium distribution of