Synthesis of crispine A analogues via an intramolecular Schmidt reaction
TL;DR: An intramolecular Schmidt reaction strategy for the synthesis of various derivatives of crispine A using azido-ketone as a key intermediate is described.
Abstract: An intramolecular Schmidt reaction strategy for the synthesis of various derivatives of crispine A using azido-ketone as a key intermediate is described.
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01 Jan 1993
TL;DR: Interestingly, the alkaloids chemistry and pharmacology volume 32 that you really wait for now is coming, it's significant to wait for the representative and beneficial books to read.
Abstract: Interestingly, the alkaloids chemistry and pharmacology volume 32 that you really wait for now is coming. It's significant to wait for the representative and beneficial books to read. Every book that is provided in better way and utterance will be expected by many peoples. Even you are a good reader or not, feeling to read this book will always appear when you find it. But, when you feel hard to find it as yours, what to do? Borrow to your friends and don't know when to give back it to her or him.
30 citations
TL;DR: An enantiospecific and stereoselective total synthesis of the natural product (+)-crispine A has been demonstrated employing a Pictet-Spengler bis-cyclization reaction between commercially available (R)-(-)-methyl 2-amino-3-(3,4-dimethoxyphenyl)propanoate and 4-chloro-1,1-Dimethoxybutane to preferentially provide the cis tricyclic adduct.
Abstract: An enantiospecific and stereoselective total synthesis of the natural product (+)-crispine A has been demonstrated employing a Pictet-Spengler bis-cyclization reaction between commercially available (R)-(-)-methyl 2-amino-3-(3,4-dimethoxyphenyl)propanoate and 4-chloro-1,1-dimethoxybutane to preferentially provide the cis tricyclic adduct. Decarboxylation by a convenient two-step protocol provided the enantiopure natural product in three steps with an overall isolated yield of 32% from the amino acid. The unnatural antipode (-)-crispine A was similarly prepared in three steps from the commercially available (S)-(+)-amino acid.
29 citations
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TL;DR: The Schmidt reaction has been modified to include analogous reactions in which the hydrazoic acid is replaced by an alkyl azide, promoted by Lewis acids as mentioned in this paper, allowing the formulation of intramolecular Schmidt reactions of the azide with a carbonyl or carbocationic electrophile.
Abstract: The classical form of the Schmidt reaction involves the reaction of a carbon-centered electrophile with hydrazoic acid with loss of nitrogen, usually with a rearrangement that forms a new carbon-nitrogen bond. Although the conversion of a ketone into an amide is the most commonly used variation, mechanistically related versions utilize an aldehyde, acid, or a carbocation generated from an alkene or alcohol as the electrophilic component. In recent years, the definition of the Schmidt reaction has been modified to include analogous reactions in which the hydrazoic acid is replaced by an alkyl azide, promoted by Lewis acids. The use of an alkyl azide uniquely permits the formulation of intramolecular Schmidt reactions of the azide with a carbonyl or carbocationic electrophile.
Keywords:
alkyl azide;
amide synthesis;
hydrazoic acid;
lactam synthesis;
rearrangement;
ring expansion;
Schmidt reaction
28 citations
TL;DR: In this article, the synthesis of cyclopropylimine rearrangement was described. But the synthesis was performed by a one-pot tandem cyclization of 1 and 6, respectively, via Bischler Napieralski reaction.
24 citations
TL;DR: This study is the first to demonstrate that the chemical constituents of P. cornucopiae display renoprotective effects against anticancer drug-induced damage in kidney cells.
23 citations
References
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01 Jan 1991
TL;DR: In this paper, the total synthesis of amaryllidaceae alkaloids has been studied using radical cyclization reactions in total syntheses of naturally occurring indole alkaloid.
Abstract: Chapter headings. Carbon-13 and proton NMR shift assignments and physical constants of diterpenoid alkaloids. Supercritical fluid extraction of alkaloids. Recent advances in the total synthesis of amaryllidaceae alkaloids. Applications of radical cyclization reactions in total syntheses of naturally occurring indole alkaloids.
1,263 citations
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01 Jan 1983
TL;DR: AAL Guantilaka, Alkaloids From Sri Lankan Flora M Lounasmaa, P Hanhinen, and M Westerund as mentioned in this paper, The Sarpagine Group of Indole AlkAloids P Popik and P Skolnick, Pharmacology of Ibogaine-Related AlkALoids A-U-Rahman and MI Choudhary, Chemistry and Biology of Steroidal Alk aloids From Marine Organisms GA Cordell, The Monoterpene Alkalinoids Subject Index
Abstract: AAL Guantilaka, Alkaloids From Sri Lankan Flora M Lounasmaa, P Hanhinen, and M Westerund, The Sarpagine Group of Indole Alkaloids P Popik and P Skolnick, Pharmacology of Ibogaine-Related Alkaloids A-U-Rahman and MI Choudhary, Chemistry and Biology of Steroidal Alkaloids From Marine Organisms GA Cordell, The Monoterpene Alkaloids Subject Index
449 citations
TL;DR: This review covers the isolation, structure determination, synthesis, chemical transformations and biological activity of indolizidine and quinolIZidine alkaloids.
281 citations
TL;DR: Most alkaloids of amphibian skin appear to be sequestered from dietary arthropods, and the source of the batrachotoxins, histrionicotoxinins, pumiliotoxin, epibatidine, and certain izidines are unknown.
Abstract: Amphibian skin has provided a wide range of biologically active alkaloids. During the past 30 years, over 400 alkaloids of over 20 structural classes have been detected. These include the batrachot...
232 citations
TL;DR: This tutorial review analyses and summarises key recent developments in the field of Schmidt reactions and concludes that the Schmidt reaction now represents an important reaction in synthetic chemistry.
Abstract: The azide group has a diverse and extensive role in organic chemistry, reflected in the power of azide anion as a strong nucleophile, the role of organic azides as excellent substrates for cycloaddition reactions, the uses of azides as precursors of amines and nitrenes, and azide rearrangements known as the Curtius and Schmidt reactions. In recent years the scope of the Schmidt reaction has begun to be explored in depth, so that it now represents an important reaction in synthetic chemistry. This tutorial review analyses and summarises key recent developments in the field of Schmidt reactions.
200 citations