A New Type of P–C and C–C Bond Cleavage Reactions in α-Trimethylsilyloxy-β-oxo Phosphonates and α-Ethoxy-β-oxo Phosphonates. The Synthesis of Unsymmetrical α-Hydroxy Ketones Utilizing 1:1 Carbonyl Adducts of Diethyl Trimethylsilyl Phosphite with Benzaldehyde

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Abstract
α-Lithiated diethyl α-(trimethylsilyloxy)benzylphosphonate underwent facile acylation with various acylating agents to afford the corresponding α-acylated products in good yields. On treatment of the α-acylated products with 1 M NaOH–EtOH (1:1, v/v) the P–C bond was cleaved with elimination of diethyl phosphate to give α-hydroxy ketones predominantly. On the other hand, when diethyl α-acyl-α-ethoxybenzylphosphonates were treated under the same conditions, they were rather stable and recovered. However, the prolonged alkaline treatment or the use of 4 M NaOH–EtOH (1:1, v/v) resulted in the C–C bond cleavage giving carboxylic acids and diethyl α-ethoxybenzylphosphonate in quantitative yields, respectively. The mechanisms of the above two reactions were proposed and discussed in connection with the Perkow reaction and related reactions.