Total Synthesis of Aspidosperma and Strychnos Alkaloids through Indole Dearomatization

Monoterpenoid indole alkaloids are the major class of tryptamine-derived alkaloids found in nature. Together with their structural complexity, this has attracted great interest from synthetic organic chemists. In this Review, the syntheses of Aspidosperma and Strychnos alkaloids through dearomatization of indoles are discussed

肺結核と梶井基次郎の文学

千葉大学大学院人文社会科学研究科研究プロジェクト報告書第184集『日本近代文学と病』 滝藤満義

Base Metal Catalyzed Isocyanide Insertions

Isocyanides are diverse C1 building blocks considering their potential to react with nucleophiles, electrophiles, and radicals. Therefore, perhaps not surprisingly, isocyanides are highly valuable as inputs for multicomponent reactions (MCRs) and other one-pot cascade processes. In the field of organometallic chemistry, isocyanides typically serve as ligands for transition metals. The coordination of isocyanides to metal centers alters the electronic distribution of the isocyano moiety, and reaction pathways can therefore be accessed that are not possible in the absence of the metal. The tunable reactivity of the isocyanide functional group by transition metals has evolved into numerous useful applications. Especially palladium-catalyzed isocyanide insertion processes have emerged as powerful reactions in the past decade. However, reports on the use of earth-abundant and cheap base metals in these types of transformations are scarce and have received far less attention. In this Minireview, we focus on these emerging base metal catalyzed reactions and highlight their potential in synthetic organic chemistry. Although mechanistic studies are still scarce, we discuss distinct proposed catalytic cycles and categorize the literature according to 1) the (hetero)atom bound to and 2) the type of bonding with the transition metal in which the (formal) insertion occurs

Iodospirocyclization of Tryptamine-Derived Isocyanides:Formal Total Synthesis of Aspidofractinine

The N-iodosuccinimide-mediated spirocyclization of tryptamine-derived isocyanides to generate spiroindolenines is reported. The products contain both an imine and an imidoyl iodide as flexible handles for follow-up chemistry. Nucleophilic addition typically occurs chemoselectively on the imine moiety with complete diastereoselectivity, providing opportunities for the construction of complex molecular frameworks. The synthetic potential of the method was showcased in the formal total synthesis of (±)-aspidofractinine

Synthesis of biologically relevant molecules

Complex polycyclic molecular scaffolds containing multiple stereocenters, as found in many natural products, present particularly appealing targets for synthetic chemists. In addition to the academic challenge of selectively constructing these intricate frameworks, many such compounds display valuable bioactivities, making them important starting points for drug discovery. As in many aspects of contemporary organic synthesis, catalysis plays a key role in many MBFTs toward biologically relevant molecules (BRMs). Recently developed catalytic methodologies allow novel types of C-C bond formations and/or unprecedented control over the stereochemical outcome of the reaction. This chapter focuses on MBFTs based on recent developments in organocatalysis and transition metal catalysis, as well as multicomponent chemistry. It also aims to demonstrate the scope and synthetic potential of the above-mentioned classes of MBFTs in the synthesis of BRMs, with illustrative examples ranging from natural products to complex pharmaceuticals