The syntheses of the allenes (±)-1,(±)-4 and (±)-6 as well as of the enriched samples (-)-1,(-)- 4 and (-)-6 are described. 1H NMR shifts and splittings induced by a mixture of the achiral salt Ag (fod) and the optically active complex (+)-Yb (hfbc) 3 are given. This procedure is recommended by the magnitude of such splittings as a means of determining the enantiomeric purity of 1, 3-disubstituted allenic hydrocarbons. The results for (-)-1 and (-)- ...
