Mathey phosphole

The 3,4-dimethyl-l-phenylphosphole (the so called Mathey-phosphole ) entered into Friedel-Crafts acylation only through its molybdenum complex (20). Elimination of the Mo(CO)5 moiety from product 21 furnished 2-acylphosphole 22 (.Scheme 5) [42],... 

Scheme 5 Friedl-Crafts acylation of the Mathey-phosphole in the coordination sphere...

Scheme 11 Diels-Alder-reaction of the Mathey-phosphole ...

The result of the complex forming reaction of the Mathey phosphole (46) is quite different as in this case, the predominant product is the bis(phosphole) complex with cis geometry. (Scheme 18) [62],... 

Scheme 18 Conversion of the Mathey-phosphole to the corresponding Pt(II) complex...

F. Mathey, Phosphole chemistry. Topics Phos. Chem., 10, 1, 1978. 

Complexing modes of the phosphole moiety. F. Mathey, J. Fischer and J. H. Nelson, Struct. Bonding (Berlin), 1983, 55,153-201 (116). 

Mathey F, Fischer J, Nelson JH (1984) Complexing Modes of the Phosphole Moiety. 55 153-201... 

The phosphacyclopentadienes with phosphine function are called 1//-phospholes and they form an important part of contemporary P-heterocyclic chemistry. Phosphole chemistry has undergone an intensive development, which is well demonstrated by the fact that while in the first edition of Comprehensive Heterocyclic Chemistry (1984), only several pages were devoted to phospholes [1], the second edition (1996) discusses this topic in a lengthy chapter [2], Besides these, exhaustive monographs have been published in P-heterocyclic chemistry also incorporating the new developments of phosphole chemistry [3, 4], The first review in the subject was written by Mathey [5],... 

A practical synthesis of phospholes (2) was suggested by Mathey. The method involves the double dehydrohalogenation of phospholium salts (1) by a suitable base, such as a-picoline to give the phospholes in good yields (Scheme 1) [24, 25],... 

Quin LD (2001) Phospholes. In Mathey F (ed) Phosphorus-carbon heterocyclic chemistry the rise of a new-domain. Pergamon, Amsterdam, Chaps 421, 422... 

Contrary to pyrrole, phospholes are not planar, due to the high inversion barrier of the tricoordinate phosphorus (cf. the 6 kcal/mol inversion barrier of ammonia with the 35 kcal/mol inversion barrier of phosphine). As a consequence, unfortunately phospholes are not aromatic (Mathey, F.). Although the aromaticity of phospholes has been disputed in the past, Mislow considered first that phospholes with pyramidal phosphorus are nonaromatic while with planar tricoordinate phosphorus aromatic phospholes could be obtained. It was just recently found that phosphorus can be flattened or even fully planarized (as discussed comprehensively ), resulting in aromatic systems (see section IV.B.l). 

Fig. 4) becomes more pronounced at the phosphorus atom in the hypervalent compound. Calculation of the aromaticity% [127] revealed similar tendencies. While phosphole itself exhibits 18% aromatic character, for phosphole oxide -13% has been reported [176], It is noteworthy that for 1-methoxyephosphole and 1-fluoro-phosphole small negative values (-4.9% and -9.2%) were also obtained, in agreement with the conclusions of Mathey and coworkers [169]. Also, the phosphole sulfide and selenide exhibited smaller antiaromaticity (-11.6% and - 9.7%, respectively) [176] than the oxide, in agreement with the data in Table 2 [61]. It is also worth noting that the decrease of the NICS value and the conjugation upon sulfur addition has been noted in a phosphole-thienyl and a phosphole-pyridyl oligomer by Delare et al. [177],... 

Like phospholes, phosphinines can also be part of extended jr-systems. In a recent work, Mathey et al. have synthesized and characterized by X-ray crystallography a dithienophosphinine 103 (Scheme 55) [308], The electronic interaction between the fused rings has been shown on the orbitals and by the decreased NICS(l) value (from -10.8 ppm to -8.8 ppm) of the phosphinine ring. 

As discussed in Section 3.15.2.1 (Scheme 3), lf/-phospholes can be transformed into 2/f-phosphoies upon heating. To date, very few stable 2f/-phospholes are known <2004ACR954>. However, a great variety of 2f/-phospholes are accessible using the lf/-phosphole/2/f-phosphole equilibrium, and their heterodiene behavior makes them powerful intermediates for the synthesis of P-heterocycles. Only the results that have appeared since 1996 are presented in this section for a general overview of the chemistry of 27f-phospholes, an excellent review by Mathey is available <2004ACR954>. 

It is amazing to note that in CHEC-II(1996) <1996CHEC-II(2)757> this head contained only six lines due to the lack of examples of this type of reactivity at that time. The situation has completely changed over the last decade with the discovery by Mathey and co-workers of several powerful chemical transformations of 2- and 2,5-halogeno-phosphole synthons. 

The chemical behavior of phosphole confirms this conclusion at —100 °C it was characterized by NMR spectra, but at room temperature it isomerizes rapidly to 2H-phosphole which dimerizes to a tricyclic compound via a 1,5-sigma tropic H-shift and a [4- -2]-cycloaddition (04ACR9549). Synthetic efforts of Mathey resulted in a lithium-based pathway for obtaining oligophospholes, allowing the investigation of electronic properties of such promising compounds. 

The reaction between 1,2,5-triphenylphosphole (4) and tolane at 230°C affords 2,3,6-triphenylphosphorin (5), m.p. 150°, directly in a 80% yield, along with diphenylmethane, which is known to be one of the main products resulting from the formation of diphenylcarbene at high temperature (F. Mathey et at., Ainer. chem. Soc., 1981, 103, 4595). This one-step synthesis of a phosphorin from a phosphole offers numerous possibilities and supplements earlier procedures (Markl, Phosphorus Sulphur, 1977, 3, 77 Ashe, Acc. chem. Res., 1978, 11, 153 Mathey, Tetrahedron Letters, 1979, 1753). 

H. Bonnard, and Mathey, J. org. Chem., 1982, AT, 2376). The initial conversions of phospholes into phosphorins involve a number of stages, the first being the treatment of the phosphole with benzoyl chloride in ether in the presence of triethylamine, for example, the preparation of 4,5-dimethy1-2--phenylphosphorin (Mathey, loQ. ait. Tetrahedron Letters, 1978, 133 J.M. Alcaraz, A. Breque, and Mathey, ibid. 1982, 1565). 4,5-Dimethyl-2-pyridylphosphorin is prepared in a similar manner. For the conversion of 1-phenylphosphole to 2--phenylphosphorin and 3,4-dimethyl-1-phenylphosphole to 4,5--dimethyl-2-(furoyl or thenoyDphosphorin see Alcaraz,... 

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