Novel Dimerization of 3-(2-Nitroethenyl)guaiazulene. A Convenient Route to Cyclopentaheptalene

Article abstract of DOI:10.1246/cl.1993.1109

Dimerization of 3-(2-nitroethenyl)guaiazulene with sodium methylate gave 5-(1-guaiazulenyl)-5,6-dihydro-9-isopropyl-1-methyl-4-nitrocyclopentahepatalene (3).On treatment with formic acid, 3 was converted into 9-isopropyl-1-methyl-4-nitrocyclopentaheptalene quantitatively.A combination of the reactions provides a convenient route to the cyclopentaheptalene derivatives.