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Neue Synthesen und Reaktionen von Phosphetaniumsalzen mit planarem Gerüst
Author(s) -
Brauer David J.,
Ciccu Antonella J.,
Heßler Gisbert,
Stelzer Othmar
Publication year - 1992
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19921250904
Subject(s) - chemistry , phosphonium , denticity , nucleophile , deprotonation , bifunctional , reactivity (psychology) , stereochemistry , medicinal chemistry , bond cleavage , ring (chemistry) , phosphorane , crystallography , crystal structure , polymer chemistry , ion , catalysis , organic chemistry , pathology , medicine , alternative medicine
Novel Syntheses and Reactions of Phosphetanium Salts with a PlanarSkeleton Cleavage of the P–Si bond of silylphosphanes R 2 P‐SiMe 3 (R = i Pr, t Bu, 2,4,6‐Me 3 C 6 H 2 ) with excess 1,3‐dihalogenpropanes X–[CH 2 ] 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 R 2 PH with X–[CH 2 ] 3 –X followed by deprotonation of the intermediate phosphonium salts [R 2 P(H)—[CH 2 ] 3 –X] + X ‐ (R e.g. t Bu; X = Br, 7b ). Silylphosphanes and secondary phosphanes with less bulky substituents preferably form open‐chain phosphonium salts with [CH 2 ] 3 –X or allyl substituents in these reactions. X‐ray structural analysis of( 3h ) reveals planar geometries for the PC 3 skeletons of the cations. The reactivity of 3b towards different types of nucleophiles [F ‐ , NH 2 ‐ , OH ‐ , OR ‐ , Fe(CO) 2 Cp ‐ , NaN(SiMe 3 ) 2 , RR′PLi] has been studied. Reaction with CsF or NaNH 2 , leads to a stable monofluoro or monoamino phosphorane, respectively, with cyclic four‐membered PC 3 skeletons. In all other cases opening of the phosphetanium ring system occurs leading to derivatives with R 2 P—[CH 2 ] 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.