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John V. Greenhill; Ashraf M. Moten

Source details: Tetrahedron 1983, 39 : 20 3405-3408.
Document type: Journal
CODEN: TETRAB
Language: EN
CNR: 5609239
Abstract
The base catalyzed N-alkylation of a series of primary and secondary enaminones has been examined in detail.The enaminone anion was found to be a weak nucleophile.Best results were obtained in tetrahydrofuran or dioxane with sodium hydride and an alkyl iodide.

Alkylation of Ketones and Aldehydes via their Nitrogen Derivatives

James K. Whitesell; Marilyn A. Whitesell

Source details: Synthesis 1983, 7 517-536.
Document type: Journal
CODEN: SYNTBF
Language: EN
CNR: 5572282

Abstract

In this review, methods for the alkylation of the aldehydes and ketones via formation of nitrogen derivatives such as enamines, metallated imines
(imine anions), metallated N,N-dialkylhydrazones (N,N-dialkylhydrazone anions), dimetallated oximes (oxime dianions), and metallated O- methyloximes (O-methyloxime anions) are described.Scope, limitations, and advantages or disadvantages of the methods over comparative reactions of enolates are also mentioned.

Intramolecular Photoarylations of N-(Haloaryl)ethyl ?-Enaminones

Tammy Tiner-Harding; Patrick S. Mariano

Source details: J.Org.Chem. 1982, 47 : 3 482-485.
Document type: Journal
CODEN: JOCEAH
Language: EN
CNR: 5570323

Abstract

The photochemistry of several N-(haloaryl)ethyl ?-enaminones was investigated in order to develop methods for preparation of tricyclic enaminone systems.The efficiencies of intramolecular photoarylations of the haloaryl systems were found to be dependent upon the wavelength of irradiation.Accordingly, irradiations of the haloaryl ?-enaminones 9a,c,d,f with Pyrex-filtered light leads to formation of the reduced N-cyclized and
C-cyclized products 9b or 9e, 8a or 8b, and 10a or 10b, respectively. The major products in these processes are the reduced materials.In contrast, irradiations of the bromoaryl enaminones 9c or 9f with Vycor-filtered light results in high yielding conversions to the C-cyclized tricyclic enaminones
10a and 10b in synthetically useful yields ranging from 50% to 85%.A discussion of reasons for these wavelength dependencies is given in terms of excited-state discrimination in these bichromophoric systems.Possible reaction mechanisms are considered.The origin of another major product, 11, generated by irradiation of 9f with Vycor-filtered light, is also discussed.

Regioselective control of N-aryl enaminone alkylation

Denise Dugat; Daniel Gardette; Jean-Claude Gramain; Bertrand Perrin

Source details: Bull.Soc.Chim.Fr. 1994, 131 : 1 66-70.
Document type: Journal
CODEN: BSCFAS
Language: EN
CNR: 5851695
Abstract
The regioselectivity of the C-alkylation of unsubstituted N-aryl enaminones prepared from cyclohexane-1,3-dione may be controlled by the nature of the base used.Our results indicate that monoalkylation is completely regioselective; lithium diisopropylamide leads to ?’-alkylated compounds while lithium bis(trimethylsilyl)amide affords ?-alkylated products.In contrast, alkylation of ?’- or ?-substituted compounds always occurs in the ?’-position regardless of the base.

Regiospecificity and Regioselectivity of the Alkylation, Acylation,

Sulfenylation and Sulfonylation of Pyrrolidine Enaminones

Thomas Burgemeister; Gerd Dannhardt; Ernst Eibler; Brigitte Paulus; Klaus

Ziereis

Source details: Arch.Pharm.(Weinheim Ger.) 1988, 321 : 345-
348.
Document type: Journal
CODEN: ARPMAS
Language: GE
CNR: 5807249

Abstract

Different methods to modify a pyrrolidine enaminone regiospecifically or regioselectively at the N- and C-atom, respectively, are described.All compounds have been isolated and characterized, in case of the alkylation reactions the ratio of regioisomers is determined by HPLC.NOE experiments are performed in order to prove the configuration of some adducts.

Reactivity of N-substituted enaminones with unsaturated carbonyl compounds

Esther Caballero; Blanca Madrigal; Manuel Medarde; Pilar Puebla; Zoila

Honores; et al.

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