3245-92-9Relevant academic research and scientific papers
Metal-Free O-Selective Direct Acylation of Amino Alcohols Through Pseudo-Intramolecular Process
Yokoyama, Soichi,Shibauchi, Hiroshi,Asahara, Haruyasu,Nishiwaki, Nagatoshi
, p. 1125 - 1133 (2019/02/01)
Efficient α-aryl-β-keto ester acylation of amine accompanied by the elimination of ethyl phenylacetate was achieved owing to the pseudo-intramolecular process. The eliminated ethyl phenylacetate could be recycled by conversion into an α-aryl-β-keto ester upon treatment with an acyl chloride in the presence of lithium bis(trimethylsilyl)amide, by which the atom economy considerably increased. Acylation using an α-aryl-β-keto ester is highly sensitive to the bulkiness of the nucleophile, which facilitated the regioselective-acylation of the less hindered amino group in diamine without protecting the other. The transacylation of α-aryl-β-keto ester with N-alkylamino alcohol resulted in chemoselective O-acylation without protecting the amino group because the hydroxy group was attracted to the reaction site of the keto ester by forming an ammonium salt. Transacylation was demonstrated to be a practically useful tool for organic synthesis because this protocol can be conducted under mild conditions with simple manipulations in the absence of any additives such as metal catalyst and base.
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.
Pd-catalyzed chemoselective carbonylation of aminophenols with iodoarenes: Alkoxycarbonylation vs aminocarbonylation
Xu, Tongyu,Alper, Howard
supporting information, p. 16970 - 16973 (2015/02/02)
Palladium-catalyzed chemoselective carbonylation of aminophenols with iodoarenes was realized by changing ligand and base. 3- or 4-Aminophenols afforded esters in high yields and selectivities using 1,3-bis(diphenylphosphino)propane as the ligand and K2CO3 as the base, and gave amides in high yields and selectivities using 1,3-bis(diisobutylphosphino)propane as the ligand and DBU as the base. 2-Aminophenol only gave amides in high yields under both conditions.
