Synthesis and Structure of Silicon-containing N-Methyl-and N-Benzoylamides of Diisopropylphosphoric Acid

摘要

Diisopropyl N-benzoyl-N-(trimethylsilyl)phosphoramidate reacts with ClCH2SiMe2Cl under mild conditions to form diisopropyl N-benzoyl-N-[(chlorodimethylsilyl)methyl]phosphoramidate (III). Diisopropyl N-methyl-N-(trimethylsilyl)phosphoramidate with ClCH2SiMe2Cl affords an N-transsilylation product which does not rearrange into diisopropyl N-[(chlorodimethylsilyl)methyl]-N-methylphosphoramidate (XV) even under severe conditions (4 h, 130°C). Compound XV was prepared by the reaction of diisopropyl phosphoro-chloridate with N-[(methoxydimethylsilyl)methyl]-N-methylamine followed by treatment of diisopropyl N-[(methoxydimethylsilyl)methyl]-N-methylphosphoramidate with boron trichloride. Analysis of experimental and calculated ~(29)Si chemical shifts points to a five-coordinate silicon atom in compound III and a four-coordinate silicon atom in compound XV. According to B3LYP calculations with due regard to solvent effects, compound III is an isomer with a C=O->Si bond. By variation of substituents at silicon, phosphorus, and carbonyl carbon atoms, chelate structures with either C=O_>Si or P=O_>Si dative bonds can be obtained.