- Electrophilic catalysis in nucleophilic substitution reactions in ionic liquids
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2-Chlorotropone was obtained from 2-tosyloxytropone in 88% yield in the recyclable ionic medium BMIMBF4/LiCl. That Li+ acts as a Lewis acid was proven by the lack of reactivity of 2-tosyloxytropone, under the above conditions, on replacing LiCl with NaCl or BMIMCl, or using BMIMCl alone, or a BMIMBF4/MeCN/KCl mixture. 2-Bromo- and 2-iodotropone were obtained along similar lines from LiBr or LiI, respectively, whereas LiF proved unreactive.
- Cavazza, Marino,Pietra, Francesco
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p. 3633 - 3634
(2007/10/03)
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- A general entry to 10-halocolchicides and 9-haloisocolchicides
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Readily accessible 10-tosyloxycolchicide (1) and LiX (X=Cl or Br or I) in MeOH/BF3·Et2O at reflux give 10-chloro- (2), 10-bromo- (4), or 10-iodocolchicide (5), in good yields. 9-Chloro- (7) and 9-bromoisocolchidide (8) can be similarly obtained from 9-tosyloxyisocolchidide (6) and the method applies also to troponoids.
- Cavazza, Marino,Pietra, Francesco
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p. 3405 - 3413
(2007/10/03)
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