- Efficient Transfer of Chelating Amides into Different Types of Esters and Lactones
-
We describe a general and versatile approach for the conversion of carboxylic acid amides into their corresponding esters despite the fact that the former are thermodynamically more stable. The transformations are mediated by the coordination of CuI by a chelating entity. The resulting weakening of the amide bond allows for nucleophilic attack by alcoholic hydroxyl functions. The principle is demonstrated for a wide variety of transformations, leading to different kinds of esters and lactones. Due to their high resonance energy, amides are generally very stable towards solvolysis. However, bispicolylamides can be activated for alcoholysis by an unusual metal coordination involving the electron pair of the amide nitrogen. Herein, we widened the scope of the reaction by transforming the amides into a range of esters and lactones.
- Jakob, Uwe,Mundinger, Stephan,Bannwarth, Willi
-
p. 6963 - 6974
(2016/02/18)
-
- Aerobic oxidation of NHC-catalysed aldehyde esterifications with alcohols: Benzoin, not the Breslow intermediate, undergoes oxidation
-
Benzoin (and neither the Breslow intermediate nor the NHC-aldehyde tetrahedral adduct) has been unambiguously identified as the oxidised species in aerobic NHC-catalysed aldehyde esterifications.
- Delany, Eoghan G.,Fagan, Claire-Louise,Gundala, Sivaji,Zeitler, Kirsten,Connon, Stephen J.
-
supporting information
p. 6513 - 6515
(2013/07/26)
-
- Platinum on carbon-catalyzed precise reduction control of trichloromethyl to Geminal-dichloromethyl groups
-
Geminal-dichloromethyl derivatives could be efficiently synthesized by the highly chemoselective platinum on carbon-catalyzed mono-dechlorination of trichloromethyl substrates in dimethylacetamide (DMA) as a specific solvent at 25 °C under a hydrogen atmosphere. Copyright
- Imanishi, Takahiro,Fujiwara, Yuta,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
-
supporting information; experimental part
p. 771 - 776
(2012/06/30)
-
- Effect of ortho substituents on carbonyl carbon 13C NMR chemical shifts in substituted phenyl benzoates
-
13C NMR spectra of 37 ortho-, meta-, and para-substituted phenyl benzoates, containing substituents in benzoyl and phenyl moiety, 4 ortho-substituted methyl and 5 ethyl benzoates as well as 9 R-substituted alkyl benzoates have been recorded. The influence of the ortho substituents on the carbonyl carbon 13C NMR chemical shift, δCO, was found to be described by a linear multiple regression equation containing the inductive, σI, resonance, σRo, and steric, EsB, or ν substituent constants. For all the ortho-substituted esters containing substituents in the acyl part as well as the phenyl part, the substituent-induced reverse inductive effect (ρIR > 0), and the negative steric effect (δorthosB were observed. In the case of ortho substituents in the phenyl part, the resonance effect was negligible. Due to inductive effect, the ortho electron-withdrawing substituents showed an upfield shift or shielding of the carbonyl carbon, while the electron-donating substituents had an opposite effect. Because of the sterical consequences, ortho substituents revealed a deshielding effect on the 13C NMR chemical shift of the carbonyl carbon. For all the meta- and para-substituted esters, the reverse substituent-induced inductive and resonance effects (ρIR4NBr and 2.25M Bu4NBr, and the IR frequencies, νCO, for the ortho-, meta-, and para-substituted phenyl benzoates and alkyl benzoates were correlated nicely with the corresponding 13C NMR substituent chemical shifts, ΔδCO. Copyright
- Nummert, Vilve,Piirsalu, Mare,Maeemets, Vahur,Vahur, Signe,Koppel, Ilmar A.
-
experimental part
p. 1155 - 1165
(2010/07/13)
-
- Copper(I)-promoted dechlorinative Surzur-Tanner rearrangement of 2,2,2-trichloroethyl carboxylates
-
(Matrix presented) 2,2,2-Trichloroethyl carboxylates undergo highly efficient dechlorinative Surzur-Tanner rearrangement with 2 equiv of a 1:1 molar mixture of CuCl and bpy in boiling DCE to give 1-chloroethenyl carboxylates in which copper appears to play an important role, probably by coordinating the initial radical or as a Lewis acid catalyst.
- Ram, Ram N.,Meher, Nabin Kumar
-
p. 145 - 147
(2007/10/03)
-
- Direct transacylation of 2,2,2-trihaloethyl esters with amines and alcohols using phosphorus(III) reagents for reductive fragmentation and in situ activation
-
Amides and esters have been synthesized from 2,2,2-trihaloethyl esters in one pot using phosphorus(III) reagents as reductants, with resultant carboxylate activation as an acyloxyphosphonium intermediate, and in situ trapping by amine or alcohol nucleophiles. Secondary and tertiary amides were synthesized, including a dipeptide, in good yields using hexamethylphosphorous triamide, (Me2N)3P, as reducing agent. Optimal yields of esters derived from primary and secondary alcohols were obtained using tributylphosphine and DMAP. Tribromoethyl esters provided yields superior to those obtained with trichloroethyl esters.
- Hans, Jeremy J.,Driver, Russell W.,Burke, Steven D.
-
p. 2114 - 2121
(2007/10/03)
-
- Selective esterification reaction involving hexaalkyl guanidinium chloride catalyst
-
A new efficient and selective esterification reaction of carboxylic acids with chloroformates is described using silica-supported catalyst (PBGSiCl). The chemioselectivity of the reaction was high particularly for sterically hindered carboxylic acids supported by a single pathway reaction.
- Gros,Le Perchec,Gauthier,Senet
-
p. 1835 - 1842
(2007/10/02)
-
- Enzymes in Organic Synthesis. 4. Investigation of the Pancreatin-Catalyzed Acylation of cis-Cyclopent-2-ene-1,4-diol with Various Trichloroethyl and Vinyl Alkanoates
-
During the pancreatin-catalyzed acetylation of the meso-diol 1 with 2,2,2-trichloroethyl acetate (2a) in tetrahydrofuran/triethylamine, the enantiomeric monoacetates 3a and ent-3a are formed at nearly equal rates. ent-3a is rapidly acetylated in a second enzyme-catalyzed step, forming 4a, whereas 3a resists further enzymatic acetylation.Thus, the monoacetate 3a can be obtained in 48 percent yield with an enantiomeric excess (e.e.) of more than 99 percent. 2,2,2-Trichloroethyl propanoate and butanoate give the corresponding monoacylation products even in slightly better yields, whereas the octanoate affords the monoacylation product with a lower enantiomeric excess. 2,2,2-Trichloroethyl monochloroacetate provides the monoacylation product in a 40 percent yield with an e.e. of 90 percent.The dichloroacetate, however, affords the diacylation product exclusively in an enzyme-independent chemical reaction.With the 2,2,2-trichloroethyl esters of isobutyric, phenylacetic, and benzoic acid no transesterification could be achieved within 24 hours.The application of vinyl acetate, however, represents a significant improvement in the synthesis of enantiomerically pure monoacetate 3a from meso-diol 1.
- Theil, Fritz,Schick, Hans,Lapitskaya, Margarita A.,Pivnitsky, Kasimir K.
-
p. 195 - 200
(2007/10/02)
-
- Pentaalkylguanidines as etherification and esterification catalysts
-
Several pentaalkylguanidines have been prepared and found to be superior catalysts for the preparation of aryl and aralkyl ethers from carbonates and for the methylation of phenols with dimethylcarbonate.They also act as effective catalysts for esterification of acids with alkyl chloroformates but not for the acetylation of tertiary alcohols with acetic anhydride.
- Barcelo, Gerard,Grenouillat, Denis,Senet, Jean-Pierre,Sennyey, Gerard
-
p. 1839 - 1848
(2007/10/02)
-
- A Simple and Mild Esterification Method for Carboxylic Acids Using Mixed Carboxylic-Carbonic Anhydrides
-
A simple and mild esterification method using mixed carboxylic-carbonic anhydrides has been developed.Simple aliphatic carboxylic esters are prepared in high yields by the reaction of acids with equimolar amounts of chloroformates (2,2,2-trichloroethyl chloroformate is an exception) and triethylamine in the presence of a catalytic amount of 4-(dimethylamino)pyridine.Although aromatic acids give a mixture of the ester, the acid anhydride, and the carbonate under normal conditions utilized in this study, it is found that increasing the amount of 4-(dimethylamino)pyridine drastically decreases the formation of the acid anhydride and the carbonate, affording a satisfactory yield of the ester.This method reaches a limit with sterically hindered acids and the formation of the acid anhydride and the carbonate is favored.
- Kim, Sunggak,Lee, Jae In,Kim, Youn Chul
-
p. 560 - 565
(2007/10/02)
-