The Chemistry of P=N−P=X (X=S, O, NR) Linkages for the Synthesis of Dendritic Structures

• Published in: ChemPlusChem (Weinheim, Germany) Vol. 88; no. 4; pp. e202300064 - n/a
• Main Authors: Maraval, Valérie, Laurent, Régis, Caminade, Anne‐Marie
• Format: Journal Article
• Language: English
• Published: Germany Wiley 01.04.2023
• Subjects: azide; Chemical Sciences; Coordination chemistry; dendrimer; dendron; phosphine; phosphorhydrazone; phosphorhydrazone; phosphine; azide; dendrimer; dendron
• ISSN: 2192-6506; 2192-6506
• DOI: 10.1002/cplu.202300064

The Staudinger reaction between a phosphine and an azide, applied to phosphorus azides, has been used for the synthesis of a large variety of dendritic structures, incorporating P=N−P=X moieties (X = mainly S, but also O and N−R). Conjugation of the P=N bond with the P=X bond greatly stabilizes the P=N bond. Highly branched structures such as dendrons, dendrimers, Janus dendrimers, layered dendrimers, surface‐block dendrimers, and diverse other dendritic structures incorporating such linkage have been elaborated. Accelerated methods of synthesis of dendrimers are also based on the Staudinger reaction. A versatile reactivity was observed exclusively on the sulfur atom of P=N−P=S linkages, such as alkylation or complexation. Alkylation on S induces a weakening of the strength of the P=S bond, which can be easily cleaved to generate phosphines able to react in Staudinger reactions inside the structure of dendrimers, thus affording highly sophisticated dendritic structures. The Staudinger reaction between phosphines and thiophosphoryl azides affords stable P=N−P=S linkages, which were used for synthesizing sophisticated dendritic structures, and also for accelerated methods of synthesis of dendrimers. Specific reactivity of such linkage occurs on sulfur with alkyl triflates, which weakens the strength of the P=S bond and can be easily cleaved. Complexation of gold was also observed.