1,5-Phosphonium betaines from N -triflylpropiolamides, triphenylphosphane, and active methylene compounds

N -Phenyl- N -(trifluoromethylsulfonyl)propiolamides react with triphenylphosphane in the presence of various active methylene compounds CH 2 XY in a 1:1:1 molar ratio to furnish 1-phosphonium-5-oxabetaines, Ph 3 P + –C(R)=CH–C(O – )=CXY. These betaines are formed preferentially, but not exclusively...

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Veröffentlicht in:Beilstein journal of organic chemistry 2019-11, Vol.15 (1), p.2603-2611
Hauptverfasser: Fiore, Vito A, Freisler, Chiara, Maas, Gerhard
Format: Artikel
Sprache:eng
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Zusammenfassung:N -Phenyl- N -(trifluoromethylsulfonyl)propiolamides react with triphenylphosphane in the presence of various active methylene compounds CH 2 XY in a 1:1:1 molar ratio to furnish 1-phosphonium-5-oxabetaines, Ph 3 P + –C(R)=CH–C(O – )=CXY. These betaines are formed preferentially, but not exclusively, as E -diastereoisomers with respect to the vinylic double bond. In some cases, separation of the two diastereoisomers was achieved by fractionating crystallization. Structure determination by X-ray diffraction analysis revealed marked conformational differences around the CH–C(O – ) single bond of E and Z -isomers and extended charge delocalization in the anionic part.
ISSN:1860-5397
2195-951X
1860-5397
DOI:10.3762/bjoc.15.253