700-44-7Relevant articles and documents
ESIPT emission behavior of methoxy-substituted 2-hydroxyphenylbenzimidazole isomers
Takagi, Koji,Yamada, Yoshihiro,Fukuda, Ryoichi,Ehara, Masahiro,Takeuchi, Daisuke
, p. 5923 - 5928 (2018)
Three 2-hydroxyphenylbenzimidazole isomers 1, 2, and 3 with the methoxy group at the 6, 4, and 3-position, respectively, were synthesized in short steps. 1 exhibited ESIPT emission irrespective of the solvent character. While 2 only showed ESIPT emission in THF and MeCN, LE emission was also observed in MeOH and a THF/water mixed solvent. These phenomena were nicely accounted for by intramolecular hydrogen bonding interactions. The fluorescence spectra of 3 always consisted of two emission bands and it exhibited strange behavior particularly in protic solvents. The fluorescence emissions in the solid state were found to be closely related to the crystal packing structure.
Evaluation of 2-(piperidine-1-yl)-ethyl (PIP) as a protecting group for phenols: Stability to ortho-lithiation conditions and boiling concentrated hydrobromic acid, orthogonality with most common protecting group classes, and deprotection via Cope elimination or by mild Lewis acids
Norén, Rolf
, (2021/04/07)
A new protecting group, 2-(piperidine-1-yl)-ethyl (PIP), was evaluated as a protecting group for phenols. The PIP group was stable to ortho-lithiation conditions and refluxing with concentrated hydrobromic acid. Deprotection was accomplished by two routes, oxidation to N-oxides followed by Cope elimination (CE) and subsequent hydrolysis or ozonolysis of the vinyl ether or one-step deprotection by BBr3?Me2S. The PIP group is orthogonal to the O-benzyl, O-acetyl, O-t-butyldiphenylsilyl, O-methyl, O-p-methoxybenzyl, O-allyl, O-tetrahydropyranyl and N-t-butoxy carbonyl groups. The CE step was systematically studied and was found to give higher yields when the reaction was performed in the presence of silylating agents.
Direct formylation of fluorine-containing aromatics with dichloromethyl alkyl ethers
Warashina, Takuya,Matsuura, Daisuke,Kimura, Yoshikazu
, p. 587 - 593 (2019/07/22)
Formylations of fluorine-containing aromatic compounds with dichloromethyl alkyl ethers have been investigated. Dichloromethyl propyl ether and dichloromethyl butyl ether have been applied for the formylation of fluorine-containing anisoles to give the corresponding aldehydes in good yields. Application of these ethers is preferable to that of methyl ether, which is prepared from volatile methyl formate. Reaction of fluorine-containing phenols with these dichloromethyl alkyl ethers did not give salicylaldehyde derivatives, leading instead to corresponding aryl formates in high yields. A plausible mechanism is discussed.
