The synthesis of the highly reactive 1, 4-unsymmetrically substituted butatrienes 12a-c is described. When employing a strict synthetic protocol, these alkatrienes react with lithium metal to 3, 4-dilithio-1, 2-butadienes 20a-c as stable intermediates. The structure of 20 is supported by IR and NMR spectroscopic evidence. The same dianionic intermediate can be prepared in one case by double deprotonation of the 1, 2-butadiene 19. Upon ...