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Phosphorus ylides are important reagents in organic chemistry, especially in the synthesis of naturally occurring products with biological and pharmacological activities. Much of the interest in the coordination properties of a-keto stabilized phosphorus ylides stems from their coordination versatility due to the presence of different ...
Crystallographic characterization of the colourless ylide reveals that the phosphorus atom is approximately tetrahedral. The PCH 2 centre is planar and the P=CH 2 distance is 1.661 Å, which is much shorter than the P-Ph distances (1.823 Å). [5] The compound is usually described as a combination of two resonance structures: Ph 3 P + CH 2 − ...
Although ylides are "electron-rich", they are susceptible to deprotonation of alkyl substituents. Treatment of Me 3 PCH 2 with butyl lithium affords Me 2 P(CH 2) 2 Li. [3] Having carbanion-like properties, lithiated ylides function as ligands. Thus Me 2 P(CH 2) 2 Li is a potential bidentate ligand. [4]
With unstabilised ylides (R 3 = alkyl) this results in -alkene product with moderate to high selectivity. If the reaction is performed in dimethylformamide in the presence of lithium iodide or sodium iodide, the product is almost exclusively the Z-isomer. [16] With stabilized ylides (R 3 = ester or ketone), the (E)-alkene is formed with high ...
The dithiophosphine ylides are normally attacked at the phosphorus atom by a nucleophile, for instance the reaction of an alkoxide, phenolate, alcohol or phenol with a 1,3,2,4-dithiadiphosphetane 2,4-disulfide can form a new compound with a phosphorus-oxygen bond.
The phosphorus is assigned position number 1 of the ring, and then the other structural features can be numbered relative to it. They can be distinguished based on where the double bond is in the phosphetene (Δ 1 -phosphetene vs Δ 2 -phosphetene) or where the double bond is missing as compared with the phosphete (1,2-dihydrophosphete vs 3,4 ...
Properties Chemical formula. C 2 H 5 NaOS Molar mass: 100.13 Appearance ... NaDMSO is used in the generation of phosphorus and sulfur ylides. [7]
It has been argued that a more accurate depiction is dipolar (i.e. (RO) 3 P +-O-), [20] which is similar to the depiction of phosphorus ylides such as methylenetriphenylphosphorane. However in contrast to ylides, the phosphoryl group is unreactive and organophosphates are poor nucleophiles, despite the high concentration of charge on the ...