Enantioselective Dehydrogenation of Alkan‐2‐ols by Gaseous (BINOLate)Ni+

Electrospray ionization of methanolic solutions of nickel(II) nitrate, 1,1′‐binaphthalene‐2,2′‐diol (BINOL), and secondary alcohols (ROH) inter alia affords monocationic complexes of the type (BINOLate)Ni(ROH)]⁺, where BINOLate stands for singly deprotonated BINOL. Upon collision‐induced dissociation (CID), the mass‐selected ions undergo competing fragmentations involving loss of the alcohol ligand and expulsion of the corresponding carbonyl compound. The latter reaction leads to the hydride complex (BINOL)Ni(H)]⁺ and can thus be regarded as the reversal of the reduction of ketones with metal hydrides. The possibility of the occurrence of enantioselective gas‐phase reactions is probed for combinations of chiral BINOLate ligands with chiral alkan‐2‐ols. Whereas aliphatic alkan‐2‐ols do not show pronounced chiral effects, enantioselective bond activation is observed for 1‐phenylethanol, indicating an interaction of the aromatic ring of the alkanol with the positively charged metal center.