- A Serendipitous Synthesis of Bis-Heterocyclic Spiro 3(2 H)-Furanones
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(Z) Enol triflates 6, 11b-d, (E) enol triflate 11e, and phenol triflate 11a, derived from β-keto esters or 2-carboalkoxy phenols, respectively, react with N-Boc 2-lithiopyrrolidine (5a), N-Boc N-methylaminomethyllithium (5b), or 2-lithio-1,3-dithiane (14) to afford 3(2H)-furanones in modest to good yields (38-81%). Product and carbanion reagent studies suggest that the 3(2H)-furanone is formed in a cascade of reactions involving nucleophilic acyl substitution, enolate formation, trifluoromethyl transfer, iminium or sulfenium ion formation, and subsequent ring closure to form the 3(2H)-furanone. The use of 2-lithio-1,3-dithiane affords a cyclic α-keto-S,S,O-orthoester in which the functionality can be selectively manipulated for synthetic applications. (Chemical Equation Presented).
- Picado, Alfredo,Li, ShengJian,Dieter, R. Karl
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p. 1391 - 1400
(2016/03/01)
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- Low-Temperature Ag/Pd-catalyzed decarboxylative cross-coupling of aryl trflates with aromatic carboxylate salts
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Chemical Equation Presented At 50°C lower than the best known copper catalysts, a catalytic silver(I)/ palladium(II) system allows the decarboxylative cross-coupling of arenecarboxylates with aryl triflates at temper-atures as low as 120°C. Remarkably, polychlorinated and many heterocyclic arenecarboxylates are converted for the first time in high yields. FG = functional group.
- Goossen, Lukas J.,Lange, Paul P.,Rodriguez, Nuria,Linder, Christophe
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supporting information; experimental part
p. 3906 - 3909
(2010/07/03)
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- Biaryl and aryl ketone synthesis via Pd-catalyzed decarboxylase coupling of carboxylate salts with aryl triflates
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A bimetallic catalyst system has been developed that for the first time allows the decarboxylative crosscoupling of aryl and acyl carboxylates with aryl triflates. In contrast to aryl halides, these electrophiles give rise to non-coordinating anions as byproducts, which do not interfere with the decarboxylation step that leads to the generation of the carbon nucleophilic crosscoupling partner. As a result, the scope of carboxylate substrates usable in this transformation was extended from ortho-substituted or otherwise activated derivatives to a broad range of ortho-, meta-, and para-substituted aromatic carboxylates. Two alternative protocols have been optimized, one involving heating the substrates in the presence of CuI/1,10- phenanthroline (10-15 mol %) and PdI2/phosphine (23 mol%) in NMP for 1-24 h, the other involving CuI/l,10-phenanthroline (615mol%) and PdBr2/Tol-BINAP (2 mol % ) in NMP using microwave heating for 5-10 min. While most products are accessible using standard heating, the use of microwave irradiation was found to be beneficial especially for the conversion of non-activated carboxylates with functionalized aryl triflates. The synthetic utility of the transformation is demonstrated with 48 examples showing the scope and limitations of both protocols. In mechanistic studies, the special role of microwave irradiation is elucidated, and further perspectives of decarboxylase crosscouplings are discussed.
- Goossen, Lukas J.,Linder, Christophe,Rodriguez, Nuria,Lange, Paul P.
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supporting information; experimental part
p. 9336 - 9349
(2010/04/03)
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- One-pot synthetic procedure for 2,2′-disubstituted biaryls via the Suzuki coupling reaction of aryl triflates in a biphasic solvent system
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A one-pot synthetic procedure for 2,2′-disubstituted biaryls was developed via a Suzuki cross-coupling reaction of aryl triflates in a biphasic solvent system. The effects of various bases and solvents were investigated. Results showed that the Na2/
- Miura, Masanori,Koike, Takanori,Ishihara, Tsukasa,Hirayama, Fukushi,Sakamoto, Shuichi,Okada, Minoru,Ohta, Mitsuaki,Tsukamoto, Shin-Ichi
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p. 3809 - 3820
(2007/10/03)
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- Coupling reactions of α-(N-Carbamoyl)alkylcuprates with enol triflates derived from cyclic β-keto esters: A facile approach to γ-carbamoyl-α,β-enoates
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α-(N-Carbamoylalkyl)cuprates couple with enol triflates derived from carbocyclic and heterocyclic (i.e., piperidinones) β-keto esters. Product yields are higher with the alkyl(cyano)cuprates [i.e., RCu-(CN)Li, 56-93%] than with the dialkylcuprate reagents (i.e., R2CuLi·LiCN). An enol nonaflate works as well as the corresponding enol triflate. A facile synthetic route to γ-amino α,β-enoates not readily prepared from γ-keto-α,β-enoates is thus established. The γ-amino-α,β-enoates, available via N-Boc deprotection, can be cyclized to annulated pyrrolin-2-ones.
- Li, ShengJian,Dieter, R.Karl
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p. 969 - 973
(2007/10/03)
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