Heterocyclic phosphorus

Phosphorus heterocyclic compounds, 1, 493-538 five-membered ring systems, 1, 513-523 nomenclature, 1, 496 six-membered ring systems, 1, 497-513 Photoaromatization oxirenes from, 7, 125-126 Photobleaching chromenes in, 3, 880 Photochemical reactions heterocyclic compound synthesis from, 5, 159 reviews, 1, 56 heterocyclic compounds reviews, 1, 71, 72... 

Ylidic four Tr-electron four-member X -phosphorus heterocycles as electronic isomers of heterocyclobutadienes 98AG(E)270. 

Yamashita M (2007) Preparation, Structure, and Biological Properties of Phosphorus Heterocycles with a C - P Ring System. 8 173-222... 

The fact that only the vinyl-substituted l,2X5-oxaphosphetanes 22 but not the arylated phosphorus heterocycles 21 undergo photofragmentations is presumably due to the inability of the latter to absorb the light (X > 280 nm) supplied for carbene formation (7- 8) [e.g. 21, Ar = C6H5 e280 200 22b, d e2g0 9000 (in methanol)]I8,20). 

The success of the ongoing series Topics in Heterocyclic Chemistry being published by Springer Verlag motivated the publisher and the then Chief Editor to bring out two special volumes on Phosphorus Heterocycles, and I was invited to shoulder this responsibility in the capacity of the Guest Editor. 

The special volume Phosphorus Heterocycles I was published last year which included the following critical review articles ... 

After receiving an enthusiastic and active response and support from the academic community, particularly the organophosphorus chemists, we intensified our efforts to bring out the special volume, Phosphorus Heterocycles II at the earliest and now it is in your hands. 

The fourth chapter Selected Five-Membered Phosphorus Heterocycles Containing a Stereogenic Phosphorus presents the description of the synthesis and use of these compounds in a few asymmetric syntheses. 

Organophosphorus compounds are important intermediates in organic synthesis and have been widely used as pharmaceutical [1-6], agricultural [7], and chemical agents [8-14], Recently phosphorus heterocycles [15,16] have received considerable interest... 

The unique combination of double bonds in the molecules of those compounds, each with different reactivity along with the easy preparation, makes phosphorylated allenes useful substrates for the synthesis of different cyclic and noncyclic organophosphorus compounds. Recent investigations increase the scope of application of phosphorylated allenes as precursors in organic syntheses. Most of them are accompanied by the formation of five- or six-membered phosphorus heterocycles, which in many cases demonstrate certain biological activity. 

Selected Five-Membered Phosphorus Heterocycles Containing a Stereogenic Phosphorus... 

Abstract This review presents the synthesis of selected five-membered phosphorus heterocycles containing a stereogenic phosphorus in an optically active form. Their utility in a few asymmetric reactions is also briefly mentioned. 

Diazaphospholes constitute the most widely investigated class of heterophospholes, the 67t-aromatic phosphorus heterocycles [1,2]. Diazaphospholes are unique in the manner that the five-membered ring incorporates one phosphorus atom. First diazaphosphole representative, i.e. 2//-[l,2,3 diazaphospholc was obtained as early as 1967 [3] and until 1980s the interest of organophosphorus chemists remained in the development of different synthetic routes and in investigating their varied reactivity due to the structural diversity within the class [4], On the basis of the relative positions of the three heteroatoms in the five-membered ring, six monocyclic diazaphosphole systems (A-F) are possible and all of them have been reported (Structure 1). 

Diazaphospholes are known to undergo facile 1,3-dipolar cycloaddditions with a variety of dipoles [2, 4, 7, 98], During recent years, some interesting [2+3] cycloaddition reactions have been reported. 2-Acyl-[l,2,3]diazaphospholes 6 were reported to undergo [2+3] cycloaddition with diazocumulene 92, the minor equilibrium isomer of a-diazo-a-silyl ketones 91, to form a bicyclic cycloadduct 93 (Scheme 29). Thermolysis of the cycloadduct results in the formation of tricyclic phosphorus heterocycle 94, which can be explained due to the possibility of two parallel reactions of cycloadduct. On the one hand, extrusion of molecular nitrogen from 93... 

Phosphorylated allenes have been widely used as building blocks for the synthesis of five- and six-membered phosphorus heterocycles [48-52],... 

Phosphorus heterocycles 246 derived from hydroxyphenyl benzimidazole and aminophenyl benzimidazole undergo oxidative cycloaddition with 3,5-di-/fV/-butyl-l, 2-bcnzoquinonc to give a mixture of 247 and 248 (Equation 60) <2004HAC307, 2004HAC321>. Oxidative addition of ort o-chloranil to bis- and tetrakis-cyclodiphos-phazene compounds gives bis- and tetrakis-spirophosphoranes, for example, 41 (Equation 61). 

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