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Synthesis of dimethyl 3‐perfluoroalkyl‐4‐(3‐oxo‐2‐triphenyl‐phosphoranylidenbutanylidene)‐pent‐2‐enedioate and its cyclization
Author(s) -
Ding WeiYu,
Cao WeiGuo,
Yao Yuan,
Zhu ZhongMei
Publication year - 1995
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.19950130515
Subject(s) - chemistry , methanol , medicinal chemistry , nuclear magnetic resonance spectroscopy , intramolecular force , trifluoromethyl , proton nmr , aqueous solution , organic chemistry , alkyl
The title compounds 5a–‐5c were prepared via the reaction of methyl 2‐perfluoroalkynoates (4) with methyl 5‐oxo‐4‐(triphenylphosphoranylidene)hex‐2‐enoate (3), which was obtained from the reaction of methyl propynate (2) with acetylmethylenetriphenylphosphorane (1) at–‐5–0°C. Intramolecular elimination of Ph 3 PO took place when compound 5 was heated in aqueous methanol at 115–120°C in sealed tube, yielding dimethyl 2‐trifluoromethyl‐4‐methylisophthalate (6a) from 5a and methyl 5‐acetyl‐4‐hydroxy‐2‐heptafluoropropanylbenzoate (6b) from 5b, respectively. The structures of compounds 5 , 6a and 6b were confirmed by IR, MS, 1 H NMR, 19 F NMR and 13 C NMR spectroscopy and elemental analyses. Reaction mechanisms for the formation of compounds 5 , 6a and 6b were proposed.