57526-28-0Relevant articles and documents
Total synthesis of rac-γ-indomycinone by Baker-Venkataraman rearrangement
Krohn, Karsten,Tran-Thien, Hoan Trang,Vitz, Juergen,Vidal, Anne
, p. 1905 - 1911 (2007)
The total synthesis of racemic γ-indomycinone (rac-3) was achieved by Baker-Venkataraman rearrangement of ester 11 to the diketone 12, acid-catalyzed cyclization to the anthrapyranone 13, followed by methyl ether cleavage and acetylation to 16, selective bromination of the branched side chain with simultaneous SN1-type hydroxy substitution to 23 and transesterification to rac-3. The corresponding γ-indomycin-one 11-methyl ether (rac-20) was prepared in a similar reaction sequence. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
2-Amino-5,6-difluorophenyl-1 H-pyrazole-Directed PdII Catalysis: Arylation of Unactivated β-C(sp3)-H Bonds
Yang, Jinyue,Fu, Xiaopan,Tang, Shibiao,Deng, Kezuan,Zhang, Lili,Yang, Xianjin,Ji, Yafei
, p. 10221 - 10236 (2019/08/20)
Palladium-catalyzed arylation of unactivated β-C(sp3)-H bonds in carboxylic acid derivatives with aryl iodides is described for the first time using 2-amino-5,6-difluorophenyl-1H-pyrazole as an efficient and readily removable directing group. Two fluoro groups are installed at the 5- and 6-position of the anilino moiety in 2-aminophenyl-1H-pyrazole, clearly enhancing the directing ability of the auxiliary. In addition, the protocol employs Cu(OAc)2/Ag3PO4 (1.2/0.3) as additives, evidently reducing the stoichiometric amount of expensive silver salts. Furthermore, this process exhibits high β-site selectivity, compatibility with diverse substrates containing α-hydrogen atoms, and excellent functional group tolerance.
Ligand-enabled β-C-H arylation of α-amino acids using a simple and practical auxiliary
Chen, Gang,Shigenari, Toshihiko,Jain, Pankaj,Zhang, Zhipeng,Jin, Zhong,He, Jian,Li, Suhua,Mapelli, Claudio,Miller, Michael M.,Poss, Michael A.,Scola, Paul M.,Yeung, Kap-Sun,Yu, Jin-Quan
supporting information, p. 3338 - 3351 (2015/03/30)
Pd-catalyzed β-C-H functionalizations of carboxylic acid derivatives using an auxiliary as a directing group have been extensively explored in the past decade. In comparison to the most widely used auxiliaries in asymmetric synthesis, the simplicity and practicality of the auxiliaries developed for C-H activation remains to be improved. We previously developed a simple N-methoxyamide auxiliary to direct β-C-H activation, albeit this system was not compatible with carboxylic acids containing α-hydrogen atoms. Herein we report the development of a pyridine-type ligand that overcomes this limitation of the N-methoxyamide auxiliary, leading to a significant improvement of β-arylation of carboxylic acid derivatives, especially α-amino acids. The arylation using this practical auxiliary is applied to the gram-scale syntheses of unnatural amino acids, bioactive molecules, and chiral bis(oxazoline) ligands.
