The hydrolysis of an iminophosphorane. Evidence for an intermediate

Mechanisms and Substituent Effects of Metal-Free Bioorthogonal Reactions

“…Chaturvedi et al studied the mechanism of the hydrolysis of phosphite iminophosphoranes. 426 The reaction rate's pH dependence was similar to that of iminophosphoranes of PPh 3 (Figure 82). 359 Hydrolysis was fast at low pH and dropped as the pH of the solution exceeded the pK a of the iminophosphorane (pK a = 6.3 for N-phenyl triethoxyiminophosphorane), and protonation of the iminophosphorane is therefore required for hydrolysis.…”

“…The reaction of phosphites with azides proceeds analogously to that with phosphines. However, the formed P–N bond is stable for phosphites, and hydrolysis leads to replacement of alkoxy groups …”

“…Chaturvedi et al studied the mechanism of the hydrolysis of phosphite iminophosphoranes . The reaction rate’s pH dependence was similar to that of iminophosphoranes of PPh 3 (Figure ).…”

“…However, the formed P−N bond is stable for phosphites, and hydrolysis leads to replacement of alkoxy groups. 426 5.9.1. Mechanism of Phosphite Iminophosphorane Hydrolysis.…”

Site-specific functionalisation of proteins by a Staudinger-type reaction using unsymmetrical phosphites

“…Based on 18 O-labelling experiments, it was suggested that the hydrolysis proceeds via nucleophilic attack partially at the sp 3 hybridised a-carbon (if present) and partially at the phosphorous atom. 30,31 If this were to be the case, substituents containing more electrophilic a-carbons should be prone to an enhanced attack by nucleophiles, and more stabilised alkoxides should be expelled from the pentavalent phosphorous transition state more readily. The results obtained for the transformation of alkyl-and phenyl-substituted phosphites are in agreement with the predicted trend.…”