(1Z,3Z)-buta-1,3-dienyl-1-lithium species and substituted tellurophenes by Te/Li exchange on (1Z,3Z)-butyltelluro-1,3-butadienes and (1Z,3Z)-1,4-bis(butyltelluro)-1,3-butadienes.

(1Z,3Z)-1-Butyltelluro-1,3-butadienes 8, 9 and 12 obtained by the hydrotelluration of but-1-en-3-ynes 1, 2 and 5 were transformed into the corresponding buta-1,3-dienyl-1-lithium by reaction with n-BuLi. 1,3-Butadienes 14, 15, 17-20 were obtained with retention of the double bond geometry by reaction of the butadienyllithium intermediates with electrophiles. The butadienyllithium 13 obtained by the Te/Li exchange reaction in the (12,3Z)-1-Butyltelluro-4-methoxy-1,3-Butadiene 8 was reacted with benzaldehyde to form the corresponding alcohol 15 with total retention of configuration, that undergoes hydrolysis resulting into the (E,E)-5-phenyl-2,3-pentadien-1-al 16. Hydrotelluration of the 1-butyltellurobut-1-en-3-cyclization, leading to substituted tellurophenes 24, 25, 27-29 via a sequential Csp(2)-Te and Csp(3)-Te bonds cleavage on reaction with n-BuLi followed by addition of electrophiles. (C) 1997 Elsevier Science Ltd.