DTBB-catalysed lithiation of 4-functionalised 1-chloro-2-butenes

The reaction of N,N-disubstituted (E)-4-amino-1-chloro-2-butenes 1 with an excess of lithium and a catalytic amount of DTBB in the presence of an electrophile [E(+)=ButCHO, PhCHO, Me(2)CO, (CH2)(5)CO, (c-C3H5)(2)CO, Me(3)SiCl] in THF at -78 degrees C leads, after hydrolysis with water, to the expected mixture of 1,2- and 1,4-disubstituted compounds (2 and 3, respectively), which could be easily separated by flash chromatography. When the reaction was applied either to the corresponding (Z)-starting materials or to (Z)- or (E)-oxygen or sulfur containing chlorinated 2-butenes the yields are poorer than for nitrogenated precursors. Copyright (C) 1996 Elsevier Science Ltd.