Homogeneous CO Hydrogenation: Ligand Effects on the Lewis Acid ...

Reaction of [1-P 2][BF 4] with 2 equiv. NaHBEt 3.
A variety of hydride sources and conditions were screened, and after workup there were always
at least two products. A representative preparation involved dissolving 120 mg (0.110 mmol)
cation [1-P 2][BF 4] in 2 mL C 6H 5Cl with stirring, followed by dropwise addition of 110 μL (0.110
mmol, 1 equiv) NaHBEt 3 (1.0 M in toluene). The mixture was stirred briefly, then allowed to
stand for 10 minutes. After filtration, to the yellow solution was added 38 mg (0.105 mmol, 0.95
equiv) dibenzo-18-crown-6, followed by another (0.110 mmol, 1 equiv) NaHBEt 3 (1.0 M in
toluene), dropwise by syringe. The clear yellow solution was stirred for two hours, filtered again,
and the solvents removed in vacuo. After washing with Et 2O, the solids were extracted in THF
and the solvents removed in vacuo. The crude THF fraction included a number of products,
including two doublets in the 1 H NMR at δ 4.63 (J HH = 17.3 Hz) and 4.78 (J HH = 16.8 Hz),
similar to those observed in other C-C bond-formed products. Isolation of the desired product
was unsuccessful, however.
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