Synthesis and Reactions of Phosphorus-Rich

Synthesis and Reactions of Phosphorus-Rich Silylphosphanes G. Fritz... 

The synthesis and structures of three phosphorus-rich organogallium cages have appeared (Figure 1), adding variety to the regular Ga P stoichiometries which have dominated work in this area for the last few years. Reaction of Li2P (Ad) with... 

Another nucleophilic entity widely used both in solution and on polymer support is phosphorus. The handling of phosphanes both pre- and post-synthesis is considered problematic, pre due to their facile oxidation (in the case of electron-rich phosphanes), post due to the formation of the corresponding oxide that makes purification of the desired product troublesome. In this case, the use of a polymer-bound phosphane shows many advantages over the solution phase reaction the phosphane is easier to handle, and purification of the desired product along with removal of the undesired phosphane oxide is simplified. 

Phosphorylation of histones is another mechanism for the neutralization of basic proteins. The phosphorylation reaction occurs after the completion of the histone synthesis. It is reversible. Phosphorylation of the lysine- and arginine-rich histones precedes an increase in RNA synthesis. This was found in transforming lymphocytes, in the regenerating liver and pancreas, etc. Histones and protamines are phosphorylated at the final stages of spermatogenesis (see review of Allfrey et al, 1964, 1972). Specific kinases which participated in the transport of phosphorus groups from ATP to histones are stimulated by cyclic AMP (Allfrey et al., 1972). 

Carbanions derived from sulfoxides, phosphonates, and phosphonium salts have a rich preparative chemistry. The fact that sulfoxides are configuration-ally stable and partake in a wide range of reactions as nucleophiles has inspired a number of investigators to examine chiral sulfoxides as auxiliaries for asymmetric synthesis [21-23]. The chemistry of phosphonates and phosphonium salts is largely dominated by their use in olefination reactions. Consequently, the applications of chiral phosphorus-stabilized carbanions in asymmetric synthesis are primarily found in the desymmetrization reaction of ketones, leading to optically active olefins. 

The exploration of the chemistry of azirines has led to the discovery of several pyrrole syntheses. From a mechanistic viewpoint the simplest is based upon their ability to behave as a-amino ketone equivalents in reactions analogous to the Knorr pyrrole synthesis cf. Section 3.03.3.2.2), as illustrated in Schemes 91a and 91b for reactions with carbanions. Parallel reactions with enamines or a-keto phosphorus ylides can be effected with electron-deficient 2//-azirines (Scheme 91c). Conversely, electron-rich azirines react with electron deficient alkynes (Scheme 91d). 

Boron, Phosphorus, and Selenium Compounds. Oxone has been used to oxidize carbon-boron bonds during the work-up of hydroboration reactions to obtain high yields of the resultant alcohols (eq 73). Aqueous Oxone/acetone oxidizes electron-poor and electron-rich aromatic and aliphatic boronic acids and esters to the corresponding alcohols rapidly and efficiently (eq 74). A one-pot procedure for the synthesis of iweta-substituted phenols from benzenes has been developed, and a similar strategy has been devised for the synthesis of Boc-oxindoles from Boc-indoles. i3i... 

---