Grignard reagents, with phosphorus esters

A further selectivity is found with the preferential displacement of aromatic ester linkages compared to alkyl ester linkages using Grignard reagents.41 In the reaction of the chiral mixed-ester phosphonite shown in Equation 4.17, preferential displacement of the aromatic ester compared to the alkyl ester occurs with inversion of configuration at phosphorus.42... 

A less common approach to the synthesis of phosphinates is the reaction of electrophilic phosphonates with carbon nucleophiles such as Grignard reagents or lithium enolates. For example, the phosphinic acid analogue 71 of the amino acid statine was synthesized by displacement of tert-butyl lithioacetate on a 5-phenyl phosphonothioate 70 (Scheme 23)d104l The racemic diastereomers of the 5-phenyl phosphonothioate were obtained in pure form, and the displacement of the phenylsulfanyl moiety was found to be stereospecific, although the stereocenter at phosphorus would later be lost on hydrolysis of the ester. A similar displacement reaction has been described using the p h osp h on och I ori d ate.1711... 

IV. Reactions of Trivalent Phosphorus Esters with Grignard Reagents. 34... 

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