"Synthetic Studies on Indoles and Related Compounds." Part XXX. A new general synthetic route for 1-substituted 4-oxygenated .BETA.-carbolines.

Suzuki, Hideharu; Yokoyama, Yuusaku; Miyagi, Chiemi; Murakami, Yasuoki

doi:10.1248/cpb.39.2170

Cited by 11 publications

(1 citation statement)

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“…Suzuki et al reported on a simple, two-step synthesis of canthinone ( 1 ) and 1-methoxycanthin-6-one ( 9 ) starting from the β-carboline-1-methyl esters 28a (Scheme ). Dibal-H reduction to the carbaldehydes ( 28b ) followed by the addition of lithium ketene acetal (derived from ethyl acetate and lithium hexamethyldisilazide) led to the direct formation of each product in good yield following an ethanol quench.…”

Section: Canthin-6-ones and Ring-fused Congenersmentioning

confidence: 99%

Progress in the Synthesis of Canthine Alkaloids and Ring-Truncated Congeners

Showalter

2013

J. Nat. Prod.

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The canthines represent a fairly large subclass of β-carboline alkaloids, with the first members described 75 years ago. Over the last 60 years, many members of the parent compound, canthin-6-one (1), have been isolated from various plant sources, principally the Rutaceae and Simaroubaceae families, and recently from fungi. Structures isolated from these sources have been the subject of total synthesis, which continues to the present day. This review gives a broad overview of synthetic approaches to canthines over a 30-year period from 1982 to 2012 and summarizes recent reports on the synthesis of less well known ring-truncated congeners. These include C-ring-truncated ("ABD", 2) and A-ring-truncated ("BCD", 3) ring systems, which are providing new scaffolds for potentially useful therapeutic applications.

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Section: Canthin-6-ones and Ring-fused Congenersmentioning

confidence: 99%

Progress in the Synthesis of Canthine Alkaloids and Ring-Truncated Congeners

Showalter

2013

J. Nat. Prod.

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Reductive Aminations of Carbonyl Compounds with Borohydride and Borane Reducing Agents

2002

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Reductive amination is an important tool for synthetic organic chemists in the construction of carbon‐nitrogen bonds. This reaction, also termed reductive alkylation, involves condensation of an aldehyde or ketone with an amine in the presence of a reducing agent. A wide variety of substrates can be used including aliphatic and aromatic aldehydes and ketones, and even benzophenones. A range of amines from ammonia to aromatic amines, including those with electron‐withdrawing substituents, can be employed. For particularly sluggish reactions, such as those involving weakly electrophilic carbonyl groups, poorly nucleophilic amines, or sterically congested reactive centers, additives such as molecular sieves or Lewis acids are often useful. This chapter focuses on those conditions in which the carbonyl component, amine, and reducing reagent react in the same vessel. This review is restricted to reductive aminations using borohydride and borane reducing agents. This chapter concentrates on reductive amination chemistry mediated by borohydride and other boron‐containing reducing agents from 1971, the year when sodium cyanoborohydride was introduced, through the middle of 1999. In addition to reductive aminations of aldehyde and ketone substrates, reactions of related structures including acetals, aminals, ketals, carboxylic acids, nitriles, and dicarbonyls that form a nitrogen‐containing ring are reviewed. Intramolecular processes in which the substrate contains both the carbonyl and amine moieties are described. The intramolecular variant is a useful method for preparing cyclic amines. All of the various boron‐containing hydride sources in reductive aminations, including labeled metal hydrides, are reviewed. Instances of reductive aminations that failed are described. Applications of this method to a solid support in parallel synthesis in combinatorial chemistry as well as reductive aminations that proceed in tandem with a second reaction such as reductive lactamizations are discussed.

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