Алкилирование енаминов, бета-дикетонов и енаминокетонов
A. V. Tkachev; S. A. Popov
Source details: Russ.J.Org.Chem. 1997, 33 : 5 601-606.
Document type: Journal
CODEN: RJOCEQ
Language: EN
CNR: 6090629
Original Source: Zh.Org.Khim. 1997, 33 : 5 660-665.
CODEN: ZORKAE
Language: RU
Abstract
Alkylation of a bicyclic enaminoketone, 1-((1R,5R)-3-amino-6,6-dimethylbicyclo[3.1.0]hex-2-en-2-yl))ethanone, with highly reactive alkyl halides (methyl iodide, benzyl halides, and allyl halides) in a two-phase system benzene-40% aqueous NaOH in the presence of benzyltriethylammonium chloride (BTEA) as phase-transfer catalyst results in formation of stable b-diketone monoimines, derivatives of the series of 1-((1R,5R)-2-alkyl-3-imino-6,6-dimethylbicyclo[3.1.0]hex-2-yl)ethanone, in 53-81% yields.
Alkylation of sterically hindered 1,3-diketones under phase-transfer conditions
A. S. Zanina; S. I. Shergina; I. E. Sokolov; M. S. Shvartsberg
Source details: Russ.Chem.Bl. 1996, 45 : 10 2389-2392.
Document type: Journal
CODEN: RCBUEY
Language: EN
CNR: 6056087
Original Source: Izv.Akad.Nauk Ser.Khim. 1996, 10 2518-2521.
CODEN: IASKEA
Language: RU
Abstract
Sterically hindered 1,3-diketones react selectively with propargyl and allyl bromides under conditions of phase transfer catalysis to give C-alkylated products, whereas reactions with butyl and benzyl chlorides yield mixtures of C- and O-isomers.An increase in the size of the substituents present in the initial 1,3-diketone hampers introduction of the second propargyl group.The propargyl-substituted 1,3-diketones undergo cyclization under the alkylation conditions to give substituted furans.
Sequence of alkylation of cyclohexane-1,3-dione. Alternative synthesis of (+/-)-angustione
A. A. Zenyuk; L. G. Lis; L. I. Ukhova
Source details: Chem.Nat.Compd.(Engl.Transl.) 1991, 27 : 4 400-403.
Document type: Journal
CODEN: CHNCA8
Language: EN
CNR: 5645800
Original Source: Khim.Prir.Soedin. 1991, 4 460-463.
CODEN: KPSUAR
Language: RU
Abstract
A method is proposed for introducing one, two, or three alkyl substituents into positions 4 and 6 of the cyclohexane-1,3-dione molecule by successive alkylation under the action of strong bases. (+/-)-Angustione (a natural -diketone) has been synthesized.
A Tandem Amino-Cope Rearrangement/Enamine Alkylation Reaction
Steven M. Allin; Martin A. C. Button; Stephen J. Shuttleworth
Source details: Syn.Lett. 1997, 6 725-727.
Document type: Journal
CODEN: SYNLES
Language: EN
CNR: 6086563
Abstract
Thermally induced (3,3)-sigmatropic rearrangement of 3-amino-1,5-diene substrates occurs to give the corresponding enamine products in high yield and with excellent trans:cis enamine selectivity.The enamine produced during the amino-Cope rearrangement has been directly derivatized, representing the first report of a tandem amino-Cope rearrangement/enamine alkylation reaction.The potential of this novel synthetic strategy is outlined.
N-alkylation of enaminones
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 β-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 β-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 β-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 α’-alkylated compounds while lithium bis(trimethylsilyl)amide affords γ-alkylated products.In contrast, alkylation of α’- or γ-substituted compounds always occurs in the α’-position regardless of the base.