Molecular addition compounds. 10. Borane adducts with N,N-Dialkylanilines for hydroboration

Borane adducts with selected N,N-dialkylanilines have been prepared and examined as hydroborating agents. The adduct H3B:NPhPr2i is a solid, considered less desirable than liquid adducts as hydraborating agents, Fortunately, the adducts H3B:(NPhBuMe)-Me-i, H3B: (NPhPrMe)-Me-i, H3B:(NPhPrEt)-Et-i, and H3B:(NPhPrPrn)-Pr-i are liquids above 0 degrees C, hydroborating 1-octene in tetrahydrofuran in less than 1 h at room temperature. Convenient procedures are described for generating gaseous diborane quantitatively, either by thermal dissociation of the borane-N,N-diisopropylaniline adduct or by the reaction of a 2.00 M solution of sodium borohydride in triglyme with a 5.40 M solution of boron trifluoride in triglyme.