tert.-butyl lithium in tetrahydrofuran; pentane T=-70 - 25°C; Yield given. Yields of byproduct given. Title compound not separated from byproducts;

in tetrahydrofuran; pentane T=-70 - 25°C; Yield given. Yields of byproduct given. Title compound not separated from byproducts;

96 h; isomerisation;