Experimental procedures for the synthesis of heptafulvene (3a), 8, 8-dichloroheptafulvene (3b), &&tetramethyleneheptafulvene (3c) and%, & (1', 4 '-dioxotetramethy1ene) heptafulvene'(2-(cyclohepta-2, 4, 6-trien-l-y1idene)-cyclopentane-l, 3-dion; 3d) are described. The most important sequences include a low-temperature reaction of tropylium salts with lithium or Grignard carbenoids (Scheme I) to give 3a and 3b as well as hydride ...
