Regiospecific synthesis of alkylphenanthrenes using a combined directed ortho and remote metalation -: Suzuki-Miyaura cross coupling strategy

Using a combined directed ortho metalation (DoM) - Suzuki-Miyaura cross coupling - directed remote metalation (DreM) approach, the alkylphenanthrenes (APs) 1-methyl- (5a), 1,7-dimethyl- (5b), 2,7-dimethyl- (5c), 7-ethyl-1-methyl- (15), and 7-tert-butyl-1-methylphenanthrenes (27) have been synthesized in four to seven steps and 21%-36% overall yields. In contrast to classical protocols, this method, which may be scaled to gram quantities, provides single isomers of APs in high purity of value as analytical standards for environmental studies. Aminocarbonylation of triflates to N,N-diethylbenzamides (9 --> 10) and anionic Fries rearrangement (23 --> 24) provide other potential links to DoM chemistry.