Tetrahydrofurfuryloxide Derivatives of Alkyl Aluminum Species

Tetrahydrofurfuryl alcohol (H-OTHF) was successfully reacted with a series of aluminum alkyls (AlR₃) to yield compounds of the general formula [R₂Al(μ-OTHF)]₂ where R = CH₃ (1), CH₂CH₃ (2), and CH₂CH(CH₃)₂ (3). Further, reactivity studies showed that the alkyls for 1 were easily exchanged, forming compounds of the general formula [Me(OR)Al(μ-OTHF)]₂ where OR = OC₆H₃(Me)₂-2,6 (4), OC₆H₃(CMe₃)₂-2,6 (5a), and OSi(C₆H₅)₃ (6). For 5a, reflux temperatures were required to get the full exchange; otherwise the asymmetric derivative [Me(OR)Al(μ-OTHF)₂AlMe₂] (5b) was isolated. The bulk powders of 1−6 were found to be in agreement with the crystal structures on the basis of elemental analyses and multinuclear solid state NMR studies. Multinuclear solution state NMR studies indicate that the alkyl OTHF derivatives have cis/trans isomers due to the chiral proton on the OTHF ligand.