Palladium-catalyzed aromatic C-H bond nitration using removable directing groups: Regiospecific synthesis of substituted o -nitrophenols from related phenols
A general and regiospecific transformation of substituted phenols into the related o-nitrophenols has been achieved via a three-step process involving the palladium-catalyzed chelation-assisted ortho-C-H bond nitration as the key step. In the process, 2-pyridinyloxy groups act as removable directing groups for the palladium-catalyzed ortho-nitration of substituted 2-phenoxypridines, and they can be readily removed in the subsequent conversion of the resulting 2-(2-nitrophenoxy)pyridines into 2-nitrophenols.
Zhang, Wei,Zhang, Jian,Ren, Shaobo,Liu, Yunkui
p. 11508 - 11516
(2015/01/09)
Alkyl-substituted benzoxazinorifamycin derivative, process for preparing the same and antibacterial agent containing the same
A novel rifamycin derivative having the formula (I): STR1 wherein X1 is an alkyl group with 1 to 6 carbon atoms or a cycloalkyl group with 3 to 8 carbon atoms; X2 is a hydrogen atom or an alkyl group with 1 to 4 carbon atoms; R1 is hydrogen atom or acetyl group; A is a group represented by the formula: STR2 wherein R2 is an alkyl group with 1 to 4 carbon atoms or an alkoxyalkyl group with 2 to 6 carbon atoms and R3 is an alkyl group with 1 to 6 carbon atoms or an alkoxyalkyl group with 2 to 6 carbon atoms, or a group represented by the formula STR3 wherein STR4 is a 3 to 9 membered cyclic amino group with 2 to 8 carbon atoms, R4 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, or salts thereof, a process for preparing the same and antibacterial agents containing the same as an effective ingredient. The rifamycin derivative of the present invention having the formula (I) shows a strong antibacterial activity against the Gram-positive bacteria and the acid-fast bacteria.
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(2008/06/13)
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