Ij. Alexander et al., TRANSITION-METAL MEDIATED ASYMMETRIC-SYNTHESIS .14. A NEW STRATEGY FOR THE REACTIVATION OF TRICARBONYLIRON COMPLEXES, Journal of organometallic chemistry, 453(1), 1993, pp. 111-115
Protonation of an exo-substituted eta4-triene complex results in a hyd
rogen shift that removes the effect of a blocking group and so provide
s a means of regenerating the eta5-cation in situations in which hydri
de abstraction would be prevented by the exo-substituent.