ISSN:
0009-2940
Keywords:
Phosphetanium salts
;
Phosphoranes
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Novel Syntheses and Reactions of Phosphetanium Salts with a Planar SkeletonCleavage of the P-Si bond of silylphosphanes R2P-SiMe3 (R = iPr, tBu, 2,4,6-Me3C6H2) with excess 1,3-dihalogenpropanes X-[CH2]3-X (X = Br, I) affords phosphetanium salts (3) in good yields. These strained four-membered ring systems are also obtained by alkylation of secondary phosphanes R2PH with X-[CH2]3-X followed by deprotonation of the intermediate phosphonium salts [R2P(H) - [CH2]3-X]+ X- (R e.g. tBu; X = Br, 7b). Silylphosphanes and secondary phosphanes with less bulky substituents preferably form open-chain phosphonium salts with [CH2]3-X or allyl substituents in these reactions. X-ray structural analysis of (3h) reveals planar geometries for the PC3 skeletons of the cations. The reactivity of 3b towards different types of nucleophiles [F-, NH2-, OH-, OR-, Fe(CO)2Cp-, NaN(SiMe3)2, RR′PLi] has been studied. Reaction with CsF or NaNH2, leads to a stable monofluoro or monoamino phosphorane, respectively, with cyclic four-membered PC3 skeletons. In all other cases opening of the phosphetanium ring system occurs leading to derivatives with R2P - [CH2]3 terminal groups. Bidentate and polydentate ligands, e.g. 19-25, with bulky substituents in terminal position have been synthesized in high yields by cleavage of 3b with mono- and bifunctional lithium phosphides. By deprotonation of 3b with MeLi the cyclic ylide 14 is formed. Treatment with acetone or benzaldehyde leads to the unsaturated open-chain phosphane oxides 15a or 15b in a Wittig-type reaction.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19921250904
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