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 |
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Hauptverfasser: | , , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
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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. |
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ISSN: | 1860-5397 2195-951X 1860-5397 |
DOI: | 10.3762/bjoc.15.253 |