Enaminones: versatile intermediates for natural product synthesis*
30 Jun 1999-Pure and Applied Chemistry (International Union of Pure and Applied Chemistry)-Vol. 71, Iss: 6, pp 979-988
TL;DR: In this article, an overview of the chemistry of enaminones and related compounds containing the structural unit N-CaC-Z (Za COR, CO2R, CN, NO2, S O 2Ar, etc.).
Abstract: Efforts in our laboratories to devise a general approach to the synthesis of alkaloids focus on the versatile reactivity of enaminones and related compounds containing the structural unit N-CaC-Z (Za COR, CO2R, CN, NO2 ,S O 2Ar, etc.). This lecture presents an overview of our research with these useful building blocks. Themes to be elaborated include chemo- selectivity and diastereoselectivity in reactions of enaminones, and the challenge of controlling absolute stereochemistry.
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TL;DR: The efficient synthesis of functionalized enamines including β-enaminoesters was effectively accomplished by the direct condensation offunctionalized sp(3) carbanions such as acetates with formamides using in situ generated HMDS base from catalytic cesium fluoride and stoichiometric tristrimethylsilylamine.
21 citations
TL;DR: Investigations aimed at the enantioselective total synthesis of indolizidine 223A, a recently described 5,6,8-trisubstituted indolIZidine alkaloid from a dendrobatid frog, are described.
Abstract: Investigations aimed at the enantioselective total synthesis of indolizidine 223A, a recently described 5,6,8-trisubstituted indolizidine alkaloid from a dendrobatid frog, are described tert-Butyl (2R,3R)-3-amino-2-ethylhexanoate and its (2S,3R)-diastereomer, prepared in several steps from lithium N-benzyl-N-[(1R)-1-phenylethyl]amide and tert-butyl (2E)-hex-2-enoate by the Davies protocol, served as chiral building blocks from which two complementary suites of diastereomeric intermediates were made en route to pivotal tert-butyl 3-[2-(alkoxycarbonylmethylene)pyrrolidin-1-yl]-2-ethylhexanoate intermediates 20 and 21 Cyclisation of these enaminones, achieved by acid hydrolysis of the tert-butyl esters and activation of the liberated carboxylic acids as mixed anhydrides, afforded 6-ethyl-7-oxo-5-propyl-1,2,3,5,6,7-hexahydroindolizine-8-carboxylate esters 28 and 29 Several further transformations of these potential scaffolds for the synthesis of the target alkaloidal systems are also reported
21 citations
TL;DR: In this article, the regioselectivity of N-tosyl carbomoylation of n-monosubstituted β-aminovinyl trifluoromethyl ketones was studied.
17 citations
TL;DR: Water-promoted hydrothiolation and hydroamination of ethyl propiolate leading to highly regioselective and stere-lective formation of thioacrylates and β-enamino esters in excellent yields, by a simple, efficient, and environmentally friendly reaction procedure without employing any hazardous reagent or solvent is reported as discussed by the authors.
Abstract: Water-promoted hydrothiolation and hydroamination of ethyl propiolate leading to highly regioselective and stereoselective formation of thioacrylates and β-enamino esters in excellent yields, by a simple, efficient, and environmentally friendly reaction procedure without employing any hazardous reagent or solvent is reported.
16 citations
TL;DR: In this paper, a simple, efficient and environmentally begin method has been developed for the synthesis of 3-aminopropenones and 3-amino-opropenoates through the reaction of 1,3-dicarbonyl compounds with amines in the presence of Cu(NO3)2 · 3H2O under solvent-free conditions.
Abstract: A simple, efficient and environmentally begin method has been developed for the synthesis of 3-aminopropenones and 3-aminopropenoates through the reaction of 1,3-dicarbonyl compounds with amines in the presence of Cu(NO3)2 · 3H2O under solvent-free conditions.
16 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
Book•
29 Jun 1993
TL;DR: This paper presents the first total Synthesis of several Natural Products Based On Alkyne-Co2(Co2)6 Complexes, and discusses the design and synthesis of Cooperative "Pinwheel" Fluorescent Sensors, and the application of Silicon-Ass Intramolecular Cross-Coupling.
Abstract: Chapter 1. The Total Synthesis Of Luzopeptins. Chapter 2. Synthesis of Geldanamycin Using Glycolate Aldol Reactions. Chapter 3. From Methylene Bridged Glycoluril Dimers To Cucurbit[N]Uril Analogs With Some Detours Along The Way. Chapter 4. Application Of Silicon-Assisted Intramolecular Cross-Coupling In Total Synthesis Of (+)-Brasilenyne. Chapter 5. Samarium(II) Promoted Ketyl Olefin Cyclizations Applied To The Total Syntheses Of (-)-Steganone And (+)-Isoschizandrin. Chapter 6. The Synthesis Of Polycavernoside A. An Example Of Conformationally Guided Macrolactonization. Chapter 7. First Total Synthesis Of Several Natural Products Based On Alkyne-Co2(Co)6 Complexes. Chapter 8. Total Synthesis Of Myriaporones 1, 3, and 4. Chapter 9. Adventures In Natural Product Synthesis: From Deep Sea Sponge To Pilot Plant. The Large Scale Total Synthesis Of The Marine Natural Product (+)-Discodermolide. Chapter 10. Synthesis Of Aprepitant. Chapter 11. Total Synthesis And Mechanism Of Action Studies On The Antitumor Alkaloid,(-)-Agelastatin A. Chapter 12. Design And Synthesis of Cooperative "Pinwheel" Fluorescent Sensors. Chapter 13. Functionalization Of Pyridines And Thiazoles Via The Halogen-Dance Reaction, Application To The Total Synthesis Of Caerulomycin C And WS75624 B. Chapter 14. Diastereoselective Intramolecular 4+3 Cycloaddition And An Enantioselective Total Synthesis Of (+)-Dactylol.
175 citations
40 citations