Topics in current chemistry, 223, New Aspects in Phosphorus Chemistry II

Critical reviews of present and future trends in modern chemical research. Specially commissioned contributions include Chemistry of Phosphanylidene Carbenoids, What to do with Phosphorus in Dendrimer Chemistry, and The Fascinating Chemistry of Triphosphabenzenes. Includes author index for volumes 201-223 and subject index. 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 New Aspects in Phosphorus Chemistry II......Page 3 Editorial Editor......Page 5 Preface......Page 7 Table of Contents......Page 9 P(RNCH2CH2)3N: Very Strong Non-Ionic Bases Usefulin Organic Synthesis......Page 11 The Asymmetric Phospho-Aldol Reaction.Past, Present and Future......Page 55 Chemistry of Phosphanylidene Carbenoids......Page 76 Transient Nitrilium Phosphanylid Complexes –New Versatile Building Blocks in Phosphorus Chemistry......Page 99 What to do with Phosphorus in Dendrimer Chemistry......Page 118 Phosphonate Chemistry and Reagents in the Synthesisof Biologically Active and Natural Products......Page 167 The Fascinating Chemistry of 1,3,5-Triphosphininesand Valence Isomers [1]......Page 221 Author Index Volume 201 -223......Page 256 Subject Index......Page 263