- The metalation of 1- and 2-(trifluoromethyl)naphthalenes: Noteworthy site selectivities
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This article provides insight into the various factors by which electronegative substituents affect the kinetic acidity of arenes and, more specifically, naphthalenes. Both 1- and 2-(trifluoromethyl)naphthalenes were consecutively treated with an organometallic or lithium dialkylamide-type base and carbon dioxide. Due to single electron-transfer triggered side reactions, the yields of (trifluoromethyl)naphthoic acids were moderate to poor. 1-(Trifluoromethyl)naphthalene was exclusively attacked at the 2-position as expected. The 2-isomer reacted with tert-butyllithium in the presence of potassium tert-butoxide solely at the 1-position, but with sec-butyllithium in the presence of N,N,N′,N′-tetramethylethylene-diamine concomitantly at the 3- and 4-positions. Authentic samples of the key acids 1, 4, 5 and 6 were prepared based on independent, unambiguous methods.
- Cottet, Fabrice,Castagnetti, Eva,Schlosser, Manfred
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p. 798 - 803
(2007/10/03)
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- Synthesis and Deamination of 7,12-Dihydrobenzanthracen-7,12-imines. A New Benzanthracene Synthesis
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The Diels-Alder reaction between isoindoles (7) and 1-naphthalyne, as generated from 1-bromo-2-fluoronaphthalene (11a), 1-bromo-2-iodonaphthalene (11b), or 1-bromo-2-naphthyl p-toluenesulfonate (11c), affords the corresponding 7,12-dihydrobenzanthracen-7,12-imine (17).Oxidative deamination of 17 with m-chloroperbenzoic acid gives the polyhalogenated benzanthracenes(3, 19a-d) in fair to good overall yields.A similar sequence with 7 and 5,6,7,8-tetrafluoro-1-naphthalyne, as generated from 1,2,3,4-tetrafluoro-5-chloronaphthalene (14a), 1,2,3,4-tetrafluoro-5-bromonaphthalene (14b), or 6-bromo-1,2,3,4-tetrafluoro- 5-naphthyl p-toluenesulfonate (16), gives, after deamination of the intermediate benzanthracenimine 18, benzanthracenes 5 and 19e in low overall yield.
- Gribble, Gordon W.,LeHoullier, Craig S.,Sibi, Mukund P.,Allen, Robert W.
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p. 1611 - 1616
(2007/10/02)
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