- Regioselective Oxidative Arylation of Fluorophenols
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A metal free and highly regioselective oxidative arylation reaction of fluorophenols is described. The relative position of the fluoride leaving group (i.e., ortho or para) controls the 1,2 or 1,4 nature of the arylated quinone product, lending versatilit
- Yu, Congjun,Patureau, Frederic W.
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- Design and synthesis of chiral urea-derived iodoarenes and their assessment in the enantioselective dearomatizing cyclization of a naphthyl amide
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A novel family of urea-derived chiral iodoarenes was designed and synthesized for use in enantioselective iodine(I/III) catalysis. Their preparation required the development of a bidirectional synthetic strategy. These new chiral iodoarenes were assessed as catalysts in the dearomatizing cyclization of a naphthyl amide and provided moderate yields of product in some cases with low enantioselectivities.
- Tariq, M.Umair,Moran, Wesley J.
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- A peptide bromoiodinane approach for asymmetric bromolactonization
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A series of 37 peptides containing an iodo-aryl amide active site were generated by means of both solid phase and conventional synthesis. These peptides were screened for asymmetric induction in the bromolactonization of 4-phenyl-4-pentenoic acid based on the generation of chiral bromoiodinane bromenium sources. The study culminated in the discovery of a tri-peptide iodo-aryl amide that effected the desired bromolactonization in quantitative conversion with 24% ee. The experiments disclosed herein provided valuable insight that ultimately facilitated the development of more synthetically useful enantioselective halocyclization methodology.
- Whitehead, Daniel C.,Fhaner, Matthew,Borhan, Babak
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supporting information; experimental part
p. 2288 - 2291
(2011/05/16)
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- General acid catalysis in the enolization of acetone
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We have used iodometry to study the enolization of acetone in water catalyzed by a series of general acids, comprised of hydrochloric acid, methanesulfonic acid, 24 aliphatic monocarboxylic acids, nine aromatic monocarboxylic acids, eight aiphatic dicarboxylic acids, and 20 monoanions of dicarboxylic acids.The log k-pK profile for unbuffered solutions of strong and moderately strong acids shows a maximum near pK ca. 0.The Broensted α value for a set of eight aliphatic monocarboxylic acids in which effects of bulk, charge, and polarizability are at a minimum is 0.56.Steric effects, probably augmented by polarizability effects in some cases, cause positive deviations from the Broensted line drawn with respect to these standard acids.Anionic carboxylic acids are also more reactive than would be predicted from their equilibrium acid strengths, whereas cationic acids tend to be less reactive.Using D2O as solvent has only a small effect on the rate of carboxylic acid catalysis.Using acetone-d6 gives values of kH/kD in the range of 7.0-8.0 at 25 deg C, values consistent with proton or deuteron being transferred between two bases of comparable strength, the carboxylate anion and the enol form of acetone.Key words: general acid catalysis, enolization, Broensted relation, steric effects, deuterium isotope effects.
- Shelly, Kevin P.,Venimadhavan, S.,Nagarajan, K.,Stewart, Ross
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p. 1274 - 1282
(2007/10/02)
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