Concise Total Synthesis of Dihydrocorynanthenol, Protoemetinol, Protoemetine, 3‐epi‐Protoemetinol and Emetine

Abstract

A concise asymmetric assembly of secologanine tryptamine and dopamine alkaloids by means of a one-pot three-component cascade reaction methodology is disclosed. This is demonstrated by the expeditious total syntheses of (-)-dihydrocorynanthenol, (-)-protoemetinol, (-)-protoemetine, (-)-3-epiprotoemetinol, and emetine (3-6 steps). The biomimetic syn-

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

“…100 A facile method for the construction of a carbazole framework was developed based on the Pd-mediated BuchwaldHartwig coupling of aniline with bromobenzene followed by Pd-promoted intramolecular oxidative cyclization. The synthesis of 1,6-dioxygenated carbazole alkaloids, clausenine (244), 6-methoxymurrayanine (245), and clausine Z (246), clausenol (247), clausine G (248), and clausine I (249), was attained using carbazole 250 as a key intermediate (Scheme 60). 101 The rst total synthesis of ekeberginine (251) was achieved using the Pd-mediated sequences (Scheme 61).…”

Combined Heterogeneous Metal/Chiral Amine: Multiple Relay Catalysis for Versatile Eco‐Friendly Synthesis

“…), [16] which has a quaternary astereocenter, was synthesized from 1 a by an aerobic oxidation/one-pot three-component cycloaddition catalytic relay using a three-catalyst system (Scheme 2 c). The one-pot threecomponent ARC synthesis of the advanced key intermediate 8 d, [17] which is employed in the total synthesis of several secologanine tryptamine alkaloids, was also successful (Scheme 2 d). The above results demonstrate that heterogeneous-palladium-catalyzed aerobic oxidation of the alcohols 1 can be performed in tandem with a large variety of aminocatalytic reactions with carbonyl compounds in one pot without inhibiting the catalytic actions of the amine catalysts.…”

Combined heterogeneous metal/organic catalysts for eco-friendly synthesis

“…Next, these compounds such as E-6b and 8d can be rapidly converted to tropane alkaloids (e.g., cocaine) [64,65] and secologanine tryptamine alkaloids [67], respectively (Scheme 2b and 2d). An aerobic oxidation/Michael/ carbocyclization cascade sequence employing the combined heterogeneous Pd/chiral amine multiple relay catalysis and molecular oxygen/air as the terminal oxidant was also investigated (Scheme 3).…”

“…Thus, the palladium (0)-aminopropyl-mesocellular foam (Pd(0)-AmP-MCF)-catalyzed aerobic oxidation [31] of alcohols 1 was linked in sequence with several chiral amine 4 [61]-catalyzed one-pot cascade transformations and provided a variety of functional molecules (e.g., aziridine 3a [62,63], E-6b [64,65], pyrrolidine 7a [66] and 8d [67]) with high enantiomeric ratios (Scheme 2). Next, these compounds such as E-6b and 8d can be rapidly converted to tropane alkaloids (e.g., cocaine) [64,65] and secologanine tryptamine alkaloids [67], respectively (Scheme 2b and 2d).…”