Phosphorus heterocycles, structure reviews

The sixth chapter, Preparation, Structure and Biological Property of Phosphorus Heterocycles with a C-P Ring System by Mitsuji Yamashita presents a very critical review of novel phosphorus heterocycles. The review discusses aliphatic 4-, 5-, 6- and 7-membered C-P-C heterocycles, aromatic C-P-C heterocycles, and various C-P-0 type heterocycles including phospha sugars. Synthetic aspects, structural studies, and the biological properties of these phosphorus heterocycles are also addressed. This chapter may attract the interest of synthetic chemists as well as heterocyclic and heteroatom chemists in the life science fields. 

Electron.—The determination of the molecular structure of phosphorus heterocycles by electron diffraction has been reviewed.176 The structures of trimethylphosphine oxide, and the corresponding sulphide in the gaseous phase, have been compared. The rotational freedom of the methyl group appears to be greater for the sulphide, which also has the longer P—C bonds, i.e. 181.8 pm for (144 Ch = S)and 180.9 pm for (144 Ch = O).177 The trifluoromethylphosphoranes (145) and (146) adopt the... 

This type of compound (152 to 155) containing one Pni, or tetra- and penta-coordinated Pv atom have been described.(1967,138anai39 1968,123 1969, ii6) Heterocycles with two P-heteroatom bonds in the ring have been more commonly reported. In addition to the numerous Pv oxyphos-phoranes and homologs, synthetised by Ramirez and co-workers (see 1968,124 for a review of these compounds) and by others,(1967,121,140 and 141 1969,147) parent tri-, tetra- and penta- coordinated phosphorus heterocyclics with various structures (156 to 162) are known.<1965,32 ... 

The molecular structure of sila-heterocycles is reviewed <98MI649>. The Raman and infrared spectra of 1-chloro-l-methylsilabutane have been studied in detail <99MI399>. The first allenic coompoimds with both silicon and phosphorus doubly bonded (ArP C Si(Ph)Tip, Tip = 2,4,6-triisopropylphenyl) have been prepared and dimerised to give 38 and 39 in the ratio of 3 2 <99MI774>. 

A brief review has recounted the discovery and applications of phosphametallocenes. The synthesis and structure of l,l -diphospha[2]ferrocenophane have also appeared these derivatives are obtained starting with 1-phenyl-3,4-dimethylphosphole-2-carboxaldehyde in a six-step synthetic procedure. A general mini-review on phosphorus heterocycles also highlights the synthesis and use of a number of phosphaferrocenes. A phospha-ferrocenium compound has also been prepared as its triiodide [Gp Fe(Ci2H2oP)][l3]- Borane adducts of phosphaferrocenes have also been obtained simply by treating the appropriate phosphaferrocenes with boron tribromide. 

Heterocyclic phosphorus ylides are a rather diverse and little known class of compounds. A variety of such structures are now known and in some cases these are of considerable synthetic value. In this chapter we have attempted to review all heterocyclic compounds containing one or more exocyclic phosphorus ylide functions, i.e. of general structure 1. It should be noted that in many cases these exist predominantly in the phosphonium ylide (P+—C ) form but for simplicity they are represented in the ylene form 1. Cyclic ylides 2 and 3 in which the phosphorus atom is within the ring are not included. 

About 20 structural studies on diphosphiranes have been reviewed in Koenig s recent accounts on three-membered ring compounds published in CHEC-II(1996) <1996CHEC-II(1)469> and in Phosphorus Carbon Heterocyclic Chemistry the... 

The importance of the substitution pattern on the phosphole in this reaction was obvious from continued studies <78JHC1319> that showed that a much higher order of reactivity and the formation of a quite different 1 2 adduct (82) could be experienced with phospholes of structure (80) and (81). Structure (82) also is novel in heterocyclic phosphorus chemistry and does not seem to have been approached by any other method (Equation (12)). 1-Phenylphosphole also reacts rapidly with the ester, but gave a mixture of products in low yield. One product is probably of the same type as (82) the other is tentatively assigned structure (83). All of these early results with acetylenedicarboxylate have been summarized in a review <81H(15)637>. In terms of mechanism, in every case it appears that the initial step is the action of the phosphorus atom as a typical nucleophilic phosphine in attacking on the triple bond (Equation (13)). Subsequent reactions involve attack on the ring carbons and on a second alkynic group, but details of these processes have not been fully established. 

The volume commences with an account of The Larock Reaction in the Synthesis of Heterocyclic Compounds by Mercedes Alvarez and colleagues at the University of Barcelona, Barcelona, Spain. This palladium-catalyzed heteroannulation of 2-iodoanihnes and substituted alkynes is now often the method of choice for the preparation of many heterocyclic derivatives since it can provide both excellent regioselectivity and high yields. This is followed by a chapter entided HeHcal Phosphorus Derivatives Synthesis and Applications by David Virieux and colleagues at the Ecole Nationale Superieure de Chimie de MontpeUier, Montpellier, France. This review surveys helical structures based on organophosphorus derivatives and describes the synthesis of heterocycHc derivatives and their applications, particularly the specificity introduced by the presence of phosphorus. 

A review entitled New phosphorus-tellurium heterocycles in the quasi-binary system RP/Te , which contains and Te NMR data, has appeared. H/ H isotope effect on the translational and rotational motion of liquid water and ammonia has been assessed by NMR measurements.The diffusion of ammonia in binary mixtures has been investigated using the pulsed-field gradient technique. A quantitative structure-property relationship of the P NMR chemical shifts has been developed for a large set of phosphines.The NMR spectrum of [P(CF3)2] has been analysed as X3MAY3 and determined.An iterative lineshape analysis of N NMR spectra of [N3] has been described. and P NMR studies of a liquid-crystalline cyclotriphos-... 

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