Jean-Pierre Majoral – författare

This series presents critical reviews of the present position and future trends in modern chemical research.

with contributions by numerous experts

Undoubtedly the chemistry of phosphorus appears more and more attractive in the sense that phosphorus presents an extraordinary versatile behaviour that allows the synthesis of a large number of different phosphorus reagents usable for applications in different fields, from biology to material science without f- getting key applications in catalysis. The full maturity of this topic of research can be explained by all the acquired knowledge over these twenty last years. Organic and inorganic chemistries of P , P and P species have been the s- in ]V v ject of thousands of publications while the chemistry of low coordinated ph- phorus derivatives experienced its hour of glory from the 1970s to the early 1990s. In parallel, interactions between phosphorus compounds and transition metals afforded many complexes, a lot of which present fascinating properties as catalysts. The interest in all these themes really is not decreasing, indeed some fas- nating areas of research are emerging or are the subject of many investigations: the medicinal chemistry of bisphosphonates, the role of phosphorus in biology, phosphorus ligands in radiopharmaceutical chemistry, phosphorus in material science, new polymers and dendrimers incorporating phosphorus, and as- metric catalysis to name but a few. Indeed researchers, benefitting from their background in basic phosphorus chemistry are developing many new fields of research.

Strong non-ionic bases are highly advantageous as stoichiometric reagents and as catalysts in synthetic organic chemistry owing to side reactions that f- quently occur when ionic bases such as LDA or alkali metal alkoxides are employed. A second reason that non-ionic bases are frequently more useful in these applications is that such bases are often more soluble in less polar organic solvents,particularly at low temperatures. Thirdly,non-ionic bases can provide reactive naked or tightly associated deprotonated substrate anions that are s- bilized by the relatively large,poorly solvated cations formed by the protonated base. In such cations,extensive positive charge delocalization can occur. Prior to our work on pro-azaphosphatranes of type 1 (Scheme 1),the very strong n- ionic bases utilized for organic transformations were largely confined to the nitrogenous bases shown below (Scheme 2). Scheme 1 Scheme 2 4 J. G. Verkade 2 Uses of Strong Nonionic Nitrogen Bases 2. 1 Amines One of the earliest strong non-ionic bases to make its appearance was Proton Sponge and its derivatives [1] and these systems have been reviewed [2].More recently Proton Sponge has been used in the palladium-catalyzed arylation of 2,3-dihydrofuran [3], and it also catalyzes Knoevenagel condensations of s- strates possessing activated methylene groups [4]. Recently the synthesis of the macrocyclic tetramine below (Scheme 3) was reported [5]. The encrypted nitrogens are very basic (pK ,24.

Undoubtedly the chemistry of phosphorus appears more and more attractive in the sense that phosphorus presents an extraordinary versatile behaviour that allows the synthesis of a large number of different phosphorus reagents usable for applications in different fields, from biology to material science without f- getting key applications in catalysis. The full maturity of this topic of research can be explained by all the acquired knowledge over these twenty last years. Organic and inorganic chemistries of P , P and P species have been the s- in ]V v ject of thousands of publications while the chemistry of low coordinated ph- phorus derivatives experienced its hour of glory from the 1970s to the early 1990s. In parallel, interactions between phosphorus compounds and transition metals afforded many complexes, a lot of which present fascinating properties as catalysts. The interest in all these themes really is not decreasing, indeed some fas- nating areas of research are emerging or are the subject of many investigations: the medicinal chemistry of bisphosphonates, the role of phosphorus in biology, phosphorus ligands in radiopharmaceutical chemistry, phosphorus in material science, new polymers and dendrimers incorporating phosphorus, and as- metric catalysis to name but a few. Indeed researchers, benefitting from their background in basic phosphorus chemistry are developing many new fields of research.

Strong non-ionic bases are highly advantageous as stoichiometric reagents and as catalysts in synthetic organic chemistry owing to side reactions that f- quently occur when ionic bases such as LDA or alkali metal alkoxides are employed. A second reason that non-ionic bases are frequently more useful in these applications is that such bases are often more soluble in less polar organic solvents,particularly at low temperatures. Thirdly,non-ionic bases can provide reactive naked or tightly associated deprotonated substrate anions that are s- bilized by the relatively large,poorly solvated cations formed by the protonated base. In such cations,extensive positive charge delocalization can occur. Prior to our work on pro-azaphosphatranes of type 1 (Scheme 1),the very strong n- ionic bases utilized for organic transformations were largely confined to the nitrogenous bases shown below (Scheme 2). Scheme 1 Scheme 2 4 J. G. Verkade 2 Uses of Strong Nonionic Nitrogen Bases 2. 1 Amines One of the earliest strong non-ionic bases to make its appearance was Proton Sponge and its derivatives [1] and these systems have been reviewed [2].More recently Proton Sponge has been used in the palladium-catalyzed arylation of 2,3-dihydrofuran [3], and it also catalyzes Knoevenagel condensations of s- strates possessing activated methylene groups [4]. Recently the synthesis of the macrocyclic tetramine below (Scheme 3) was reported [5]. The encrypted nitrogens are very basic (pK ,24.

with contributions by numerous experts