Arene-Catalysed Lithiation of 1,4-Dichlorobut-2-enes and 3,4-Dichlorobut-1-ene and Reaction with Electrophiles: A Common Reaction Pathway

Article abstract of DOI:10.1016/S0040-4020(01)85269-8

The reaction of (Z) or (E)-1,4-dichlorobut-2-ene (1, 2), or 3,4-dichlorobut-1-ene (3) with an excess of lithium powder and a catalytic amount of 4,4'-di-tert-butylbiphenyl (5 molpercent) in the presence of an electrophile <(CH2)4CO, Bu^tCHO, Me3SiCl> in THF at 0 deg C yields, after hydrolysis, the corresponding 1,4- and 1,2-disubstituted compounds (Z/E)-4 and 5, the ratio of them being independent on the starting material.In the case of compounds 4 the Z-diastereomer is largely the major one.When dichlorodiethylsilane was used as electrophile the corresponding substituted silacyclopentene 6 was the only reaction product isolated.A possible mechanism involving dilithiated species is proposed.