6269-99-4Relevant academic research and scientific papers
Microwave-Assisted Synthesis of 2-Substituted 2-Thiazolines and 5,6-Dihydro-4 H -1,3-thiazines
Bisceglia, Juan A.,Kilimciler, Natalia B.,Mancinelli, Michele,Mollo, María C.,Orelli, Liliana R.
, p. 1666 - 1679 (2020/06/01)
An efficient and general method for the synthesis of 2-substituted thiazolines and 5,6-dihydro-4 H -1,3-thiazines is developed via microwave-assisted ring closure of ω-thioamidoalcohols promoted by ethyl polyphosphate (PPE). The cyclization reaction involves an S N 2-type mechanism and features the advantages of very short reaction times, high yields and a predictable stereochemical outcome. The acyclic precursors are prepared in high overall yields by an improved diacylation-thionation-saponification sequence from commercially available ω-amino alcohols. The whole process is metal-free and operationally simple.
Microwave-Assisted Synthesis of 2-Aryl-2-oxazolines, 5,6-Dihydro-4H-1,3-oxazines, and 4,5,6,7-Tetrahydro-1,3-oxazepines
Mollo, María C.,Orelli, Liliana R.
supporting information, p. 6116 - 6119 (2016/12/09)
The first general procedure for the synthesis of 5- to 7-membered cyclic iminoethers by microwave-assisted cyclization of ω-amido alcohols promoted by polyphosphoric acid (PPA) esters is presented. 2-Aryl-2-oxazolines and 5,6-dihydro-4H-1,3-oxazines were efficiently prepared using ethyl polyphosphate/CHCl3. Trimethylsilyl polyphosphate in solvent-free conditions allowed for the synthesis of hitherto-unreported 4,5,6,7-tetrahydro-1,3-oxazepines. The method involves good to excellent yields and short reaction times.The reaction mechanism and the role of PPA esters were investigated in a chiral substrate.
Ammonium nitrate: A biodegradable and efficient catalyst for the direct amidation of esters under solvent-free conditions
Ramesh, Perla,Fadnavis, Nitin W.
supporting information, p. 138 - 140 (2015/02/19)
A simple, metal-free, and environment-friendly procedure is developed for the direct conversion of esters to amides using ammonium nitrate as a catalyst under solvent-free conditions. Aryls, heteroaryls, and aliphatic esters are easily converted to the corresponding amides in excellent isolated yields (85-99%). An enantiopure ester and amine were both shown to react without racemization. The methodology has been successfully applied to preparation of procainamide.
Carboxyl activation of 2-mercapto-4,6-dimethylpyrimidine through n-acyl-4,6-dimethylpyrimidine-2-thione: A chemical and spectrophotometric investigation
Rajan
, p. 287 - 291 (2015/01/30)
2-Mercapto-4,6-dimethylpyrimidine, as effective carboxyl activating group, has been successfully proved by converting it into respective acyl derivatives and the subsequent conversion to the amides and esters respectively using amines, amino alcohols and alcohols. The aminolysis and esterification were monitored chemically and spectrophotometrically. This paved way to establish that the above mercaptopyrimidine derivative is an efficient carboxyl activating group applicable in solid phase peptide synthesis.
Amidation of esters with amino alcohols using organobase catalysis
Caldwell, Nicola,Campbell, Peter S.,Jamieson, Craig,Potjewyd, Frances,Simpson, Iain,Watson, Allan J. B.
, p. 9347 - 9354 (2014/12/11)
A catalytic protocol for the base-mediated amidation of unactivated esters with amino alcohol derivatives is reported. Investigations into mechanistic aspects of the process indicate that the reaction involves an initial transesterification, followed by an intramolecular rearrangement. The reaction is highly general in nature and can be extended to include the synthesis of oxazolidinone systems through use of dimethyl carbonate.
Carboxyl activation of 3-mercapto-5,6-diphenyl-1,2,4-triazine through N-phenylacetyl-5,6-diphenyl-1,2,4-triazine-3-thione
Rajan
, p. 119 - 126 (2019/01/21)
The carboxyl activation ability of 3-mercapto-5,6-diphenyl-1,2,4-triazine has been established by coverting it into N-phenylacetyl-5,6-diphenyl-1,2,4-triazine-3-thione and this was then subjected to aminolysis and esterification with amines and alcohols respectively and selective aminolysis with aminoalcohols-monitoring chemically and confirmed spectrophotometrically by UV-Visible scannings. It could be proved that 3- mercapto-5,6-diphenyl-1,2,4-triazine is an efficient carboxyl activating group which can be successfully applied in solid phase peptide synthesis.
Umpolung Amide Synthesis using substoichiometric N-iodosuccinimide (NIS) and oxygen AS a terminal oxidant
Schwieter, Kenneth E.,Shen, Bo,Shackleford, Jessica P.,Leighty, Matthew W.,Johnston, Jeffrey N.
supporting information, p. 4714 - 4717 (2015/04/27)
Umpolung Amide Synthesis (UmAS) provides direct access to amides from an α-bromo nitroalkane and an amine. Based on its mechanistic bifurcation after convergent C-N bond formation, depending on the absence or presence of oxygen, UmAS using substoichiometric N-iodosuccinimide (NIS) under aerobic conditions has been developed. In combination with the enantioselective preparation of α-bromo nitroalkane donors, this protocol realizes the goal of enantioselective α-amino amide and peptide synthesis based solely on catalytic methods.
Organobase-catalyzed amidation of esters with amino alcohols
Caldwell, Nicola,Jamieson, Craig,Simpson, Iain,Tuttle, Tell
supporting information, p. 2506 - 2509 (2013/06/27)
A base-mediated procedure for the amidation of unactivated esters with amino alcohols is reported. Optimization and exemplification of the catalytic process are described, furnishing products in 40-100% isolated yield.
Direct synthesis of amides from carboxylic acids and amines using B(OCH2CF3)3
Lanigan, Rachel M.,Starkov, Pavel,Sheppard, Tom D.
, p. 4512 - 4523 (2013/06/05)
B(OCH2CF3)3, prepared from readily available B2O3 and 2,2,2-trifluoroethanol, is as an effective reagent for the direct amidation of a variety of carboxylic acids with a broad range of amines. In most cases, the amide products can be purified by a simple filtration procedure using commercially available resins, with no need for aqueous workup or chromatography. The amidation of N-protected amino acids with both primary and secondary amines proceeds effectively, with very low levels of racemization. B(OCH2CF3)3 can also be used for the formylation of a range of amines in good to excellent yield, via transamidation of dimethylformamide.
Polymer-mounted N3=P(MeNCH2CH2) 3N: A green, efficient and recyclable catalyst for room-temperature transesterifications and amidations of unactivated esters
Chintareddy, Venkat Reddy,Ho, Hung-An,Sadow, Aaron D.,Verkade, John G.
experimental part, p. 6523 - 6529 (2011/12/21)
Merrifield resin-supported N3P(MeNCH2CH 2)3N shows excellent activity in the transesterification of higher esters such as glyceryl tribenzoate to methyl esters. The catalyst was successfully cycled 20 times (albeit with an increase in reaction time) without compromising yield up to the 20th cycle. The catalyst also showed good performance in amidation reactions of unactivated esters with amino alcohols.
