Related Experiment Video
Updated: Jan 14, 2026
A Protocol for Safe Lithiation Reactions Using Organolithium Reagents
Published on: November 12, 2016
Dealkylation as a Strategy to Synthesize Unconventional Lithium Salts from ortho-Phenyl-phosphonate-boranes
Anthony D Kornokovich1, Arnold L Rheingold2, Vallabha R Rikka3
1Department of Chemistry, Case Western Reserve University, 2080 Adelbert Road, Cleveland, Ohio 44106, United States.
Abstract:
Several ortho-phenyl-phosphonate-boranes 1-BR2-2-{P(O)(OEt)2}C6H4 (R = Cy (cyclohexyl, 2a), Ipc ((+)-isopinocampheyl, 2b), and nHx (n-hexyl, 2c)) have been prepared and characterized. Compounds 2a-c can be selectively mono-dealkylated to afford the corresponding lithium ortho-phenyl-boratophosphonate salts [Li(S)n][1-BR2-2-{P(O)2(OEt)}C6H4] (S = MeCN or EtOAc). All compounds were characterized by multinuclear NMR spectroscopy (1H, 13C{1H}, and 31P{1H}). Reactions of 2a with NaI or KI yielded the respective [Na(MeCN)][1-BCy2-2-{P(O)2(OEt)}C6H4] ([Na(MeCN)][3]) and [K(MeCN)][1-BCy2-2-{P(O)2(OEt)}C6H4] ([K(MeCN)][3]) salts. Single-crystal X-ray diffraction studies of 2a and [Li(MeCN)2][1-BCy2-2-{P(O)2(OEt)}C6H4] ([Li(MeCN)2][3]) document the presence of intramolecular P═O···B interactions that form pseudo-heterocyclic rings. In the solid state, [Li(MeCN)2][3] exists as a lithium-bridged dimer. Thermogravimetric analysis of [Li(MeCN)2][3] reveals high thermal stability with a decomposition onset above 200 °C. [Li(MeCN)2][3] displays good to excellent solubility in many organic solvents. Reactions of [Li(MeCN)2][3] with chlorotrimethylsilane, methyl triflate, and HCl·Et2O yielded the new ortho-phenyl-phosphonate-boranes 1-BCy2-2-{P(O)(OE)(OEt)}C6H4 (E = Me3Si, Me, H). Compounds 2a and [Li(MeCN)2][3] are weakly emissive in solution and in the solid state, with evidence of solvent-dependent dual emission.
Related Concept Videos
03:08Hydroboration-Oxidation of Alkenes
01:10α-Alkylation of Ketones via Enolate Ions
01:19Acid Halides to Alcohols: LiAlH4 Reduction
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
02:23Alcohols from Carbonyl Compounds: Reduction
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
01:15Acid Halides to Alcohols: Grignard Reaction
Grignard reagents are a source of carbanions and function as nucleophiles. The mechanism begins with the nucleophilic attack by the carbanion at the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs,...