Directed Metalation–Suzuki–Miyaura Cross-Coupling Strategies: Regioselective Synthesis of Hydroxylated 1-Methyl-phenanthrenes
摘要:
A general, efficient, and regioselective synthesis of a series of hydroxylated 1-methylphenanthrenes 9 by a combined directed ortho metalation (DoM)-Suzuki-Miyaura cross-coupling directed remote metalation (DreM) sequence is reported. Diversity to this methodology was achieved by a regioselective DoM rather than DreM reaction, affording more highly substituted phenanthrols (Table 2). Application of the turbo-Grignard reagent (i-PrMgCl-LiCl) in the Ni-catalyzed Corriu-Kumada reaction gave efficient decarbamoylation (Tables 3 and 4). Additional features are the TMS protecting group and halo-induced ipso-desilylation tactics applied to the regioselective synthesis of phenanthrenes (Scheme 2).
The directed <i>ortho</i> metalation - palladium catalyzed cross coupling connection. A general regiospecific route to 9-phenanthrols and phenanthrenes. Exploratory further metalation
作者:Jian-min Fu、Victor Snieckus
DOI:10.1139/v00-055
日期:2000.6.1
A new general and regiospecific synthesis of 9-phenanthrols (1 +2 3 4, Scheme 1, Table 1) proceeding by a Directed ortho Metalation (DoM), Suzuki-Miyaura cross coupling, and a new LDA-mediated Directed remote Metalation sequence is described. The facile Pd-catalyzed hydrogenolysis of the phenanthrols 4 into the corresponding phenanthrenes 5 via their triflates 18 translates the original DoM regioselectivity