الفهرس 
Synthesis of Thiaphosphetane,Thiadiphosphetane andOnly 14 pages are availabe for public view
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Abstract
The active phosphacumulene ylides namely, N-phenylimino- (2), 2-
oxo- (4) or 2-thioxo-vinylidenetriphenyiphosphorane (6) are nucleophilic
reagents which can be considered as versatile synthons for the synthesis
of new heterocycles. Moreover, It is well known that Lawesson’s reagent
[2,4-bis(4-methoxyphenyl)- 1 ,3,2,4-dithiaphosphetane-2,4-disulfide] (la)
exisfs in equilibrium with the monomeric form (ib). This reagent is used
as thionating agent and in the synthesis of heterocyclic thiophosphoryl
compounds.
A comparative study on the reactivity of the different phosphacumu
lenes 2, 4 and 6, phosphallene 8 ylides and the iminophosphorane 10,
towards Lawesson’s reagent 1, has been performed, to produce new
bioactive phosphorus substances. When Lawesson’s reagent 1, was
allowed to react with the active phosphacumulene ylides 2, 4 and 6, the
reactions proceed by addition with cyclization to give the new four
membered thiaphosphetane derivatives 3b, 5 and 7 respectively. When
two moles of Lawesson’s reagent were allowed to react with one mole of
(2-oxovinylidene)triphenylphosphorane (4), the same thiaphosphetanone
5 was obtained, and no thionation to the carbonyl group occured to get
the thioanalogue derivative 7.