5457-66-9Relevant academic research and scientific papers
Gram-Scale Preparation of Acyl Fluorides and Their Reactions with Hindered Nucleophiles
Barbasiewicz, Micha?,Tryniszewski, Micha?
, (2021/11/30)
A series of acyl fluorides was synthesized at 100 mmol scale using phase-transfer-catalyzed halogen exchange between acyl chlorides and aqueous bifluoride solution. The convenient procedure consists of vigorous stirring of the biphasic mixture at room temperature, followed by extraction and distillation. Isolated acyl fluorides (usually 7-20 g) display excellent purity and can be transformed into sterically hindered amides and esters when treated with lithium amide bases and alkoxides under mild conditions.
Selective Construction of C?C and C=C Bonds by Manganese Catalyzed Coupling of Alcohols with Phosphorus Ylides
Liu, Xin,Werner, Thomas
, p. 1096 - 1104 (2020/12/31)
Herein, we report the manganese catalyzed coupling of alcohols with phosphorus ylides. The selectivity in the coupling of primary alcohols with phosphorus ylides to form carbon-carbon single (C?C) and carbon-carbon double (C=C) bonds can be controlled by the ligands. In the conversion of more challenging secondary alcohols with phosphorus ylides the selectivity towards the formation of C?C vs. C=C bonds can be controlled by the reaction conditions, namely the amount of base. The scope and limitations of the coupling reactions were thoroughly evaluated by the conversion of 21 alcohols and 15 ylides. Notably, compared to existing methods, which are based on precious metal complexes as catalysts, the present catalytic system is based on earth abundant manganese catalysts. The reaction can also be performed in a sequential one-pot reaction generating the phosphorus ylide in situ followed manganese catalyzed C?C and C=C bond formation. Mechanistic studies suggest that the C?C bond was generated via a borrowing hydrogen pathway and the C=C bond formation followed an acceptorless dehydrogenative coupling pathway. (Figure presented.).
Zn(OTf)2-promoted chemoselective esterification of hydroxyl group bearing carboxylic acids
Mamidi, Narsimha,Manna, Debasis
, p. 2386 - 2396 (2013/05/21)
Selective esterification of aliphatic and aromatic carboxylic acids with various alcohols is studied using triphenylphosphine, I2, and a catalytic amount of Zn(OTf)2. Use of this catalyst allows the formation of esters at a faster rate with good to excellent yield by activating the in situ generated acyloxyphosphonium ion intermediate. During the esterification process, both their aromatic and aliphatic hydroxyl groups are fully preserved from transesterification. The results show that the bulkiness and the reactivity of this doubly activated intermediate III control the selectivity and the rate of the reaction, respectively. The method is also useful for direct amidation reactions.
Parallel synthesis of an ester library for substrate mapping of esterases and lipases
Morley, Krista L.,Magloire, Vladimir P.,Guerard, Christine,Kazlauskas, Romas J.
, p. 3005 - 3009 (2007/10/03)
Use of solid-supported reagents simplified routine acylation of primary and secondary alcohols because it eliminated traditional purification. Using a parallel synthesizer, eight primary or secondary alcohols reacted with acid chloride in the presence of poly(4-vinylpyridine), which acted as a base and acylation catalyst. Filtration, subsequent addition of amino-functionalized silica gel to remove excess acid chloride and a second filtration affording the corresponding esters in high yield (70-98%), excellent chemical purity (93-99%). Acylation of enantiopure alcohols yielded enantiopure esters. Acylation of two tertiary alcohols gave esters in low yield (27-57%) and variable chemical purity (57-99%).
Improved ester interchange catalysts
Kissling, Rebecca M.,Gagne, Michel R.
, p. 4209 - 4212 (2007/10/03)
(equation presented) Mixed alkoxide/aryloxide clusters are long-lived and milder than previously reported ester interchange catalysts. They completely transform difficult substrates in a single synthetic operation with lower catalyst and reagent ester loadings. In addition to superior activities, these mixed clusters are kinetically less basic toward enolizable esters.
Calcium Hypochlorite-Mediated Oxidation of Primary Alcohols to Methyl Esters
McDonald, Chriss E.,Nice, Lois E.,Shaw, Anthony W.,Nestor, Nestor B.
, p. 2741 - 2744 (2007/10/02)
Primary aliphatic alcohols can be converted to methyl esters using calcium hypochlorite as the oxidant.Primary benzyl alcohols can also be converted efficiently to methyl benzoates.
S,S-Bis Dithiocarbonate. A New Reactive Coupling Agent for the Direct Esterification of Carboxylic Acids
Kim, Sunggak,Kim, Sung Soo
, p. 1017 - 1019 (2007/10/02)
S,S-Bis dithiocarbonate, prepared from 4,6-dimethyl-2-pyrimidinethiol hydrochloride and phosgene in the presence of triethylamine in dichloromethane/toluene, is a new reactive coupling agent for the direct esterification of carboxylic acids with alcohols.
Copper Ion Promoted Esterification of S-2-Pyridyl Thioates and 2-Pyridyl Esters. Efficient Methods for the Preparation of Hindered Esters
Kim, Sunggak,Lee, Jae In
, p. 1712 - 1716 (2007/10/02)
The esterification of the S-2-pyridyl thioates and 2-pyridyl esters with alcohols in acetonitrile is greatly facilitated by the addition of cupric bromide and copper ion is observed to catalyze the reaction.The ester formation is found to be sensitive to solvents, metal salts, and reaction temperatures.The esterification of S-2-pyridyl thioates is much more rapid than the esterification of 2-pyridyl esters under the reaction conditions employed.This method is exceedingly effective in the preparation of sterically hindered esters and has advantages over known methods in many respects such as high yields, the mildness of the reaction, and the rapidity of the reaction.
