A simple synthesis of enamides from ketoximes

Boar, Robin B.; McGhie, J. F.; ROBINSON, MICK; Barton, D. H. R.; Horwell, David C.; Stick, Robert V.

doi:10.1039/p19750001237

Cited by 60 publications

(19 citation statements)

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“…Einige ausgewahlte Bindungsabstande und -winkel sind in den Tabellen 1 -4 zusammengestellt. (4) 154 .O ( 4) 149.7 ( 4) 152.0 (4) 150. 5( 4) 132.6( 4) 146.7( 4 ) 139.5( 4) 139.1 ( 4) 138.…”

Section: Rontgenstrukturanalyse Von 11 Und 19 *P)unclassified

“…(4) 154 .O ( 4) 149.7 ( 4) 152.0 (4) 150. 5( 4) 132.6( 4) 146.7( 4 ) 139.5( 4) 139.1 ( 4) 138. 4( 4) 138.1 (4) 137.8 (5) 138.2 ( 4) 149.0 (4) Tab.…”

Section: Rontgenstrukturanalyse Von 11 Und 19 *P)mentioning

confidence: 99%

“…AnschlieDend dampft man ein (Rotationsverdampfer) und chromatographiert an Kieselgel (Laufmittel Essigester). Neben 0.39 g (21 YO) 4-(Acetylamino)-1,2,3,4-tetrahydrocarbazol erhalt man 0.25 g (10%) ( 3 ) -0.0811 (7) 0.0724 (4) -0.3155 (4) 0.1965 ( 3 ) -0.1972 (3) 0.2466 ( 4 ) 0.3835 (4) 0.4028 ( 5 ) 0.2916 ( 5 ) 0.1552 (5) 0.1324 ( 4 ) 0.0024 ( 4 ) 0.0384 (4) -0.0676 (4) -0.2250 ( 5) -0.2271 (4) -0.1348 (4) -0.1552 (5) 0.0074 (5) -0.0289 (5) 0.1300 (9) -0.2860 (4) -0.3426(6) 0.3850 (4) 0.3975 (5) 0.4676 (6) 0.5261 (6) 0.5157 (6) 0.4430 (5) 0.0678 ( 1 ) 0.1789 (4) 0.0495 (4) 0.4203 ( 5 ) 0.3673 (4) -0.1488 (4) 0.1055 ( 4 ) 0.0803 ( 4 ) 0.1679 (5) 0.2257 ( 6 ) 0.2807 ( 6 ) 0.2769 (6) 0.2193 ( 5) 0.1611 …”

Section: N-~l-[l-(phenylsulfonyl)-3-indolyl]vinyl~acetamid (9) Und N-unclassified

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Indole und Indolalkaloide, XXI. Darstellung von 4‐(Acetylamino)‐1,2,3,9a‐tetrahydrocarbazol‐Derivaten durch [4+2]‐Cycloadditionen an 3‐Indolyl‐enimiden und ‐enamiden

1986

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Durch Einwirkung von Acetanhydrid in Pyridin auf die Oxime der 3-Acetylindole 1 und 5 lassen sich die Enimide 2 und 7 darstellen, die bei Raumtemperatur langsam Cycloadditionen rnit Acrolein und Acrylsaurederivaten zu 3 bzw. 10 eingehen. 7 1aBt sich zum Enamid 9 solvolysieren, welches in guten Ausbeuten und unter milden Bedingungen mit Acrolein und Acrylsaurederivaten zu den Addukten 11 -13 reagiert. Auf analoge Weise erhalt man aus dem 4-Oxotetrahydrocarbazoll4 uber das entsprechende Enamid 18 die tetracyclische Verbindung 19. -Die hier beschriebenen konjugierten Enimide und Enamide stellen neuartige Dienc der Indolreihe dar, bei denen die Indoldoppelbindung Teil emes speziell substituierten 3-Vinylindol-Systems ist. -Die Strukturen von 11 und 19 sind durch Rontgenstrukturanalysen gesichert.(Q VCH Verlagsgesellschaft mbH, D-

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“…Einige ausgewahlte Bindungsabstande und -winkel sind in den Tabellen 1 -4 zusammengestellt. (4) 154 .O ( 4) 149.7 ( 4) 152.0 (4) 150. 5( 4) 132.6( 4) 146.7( 4 ) 139.5( 4) 139.1 ( 4) 138.…”

Section: Rontgenstrukturanalyse Von 11 Und 19 *P)unclassified

“…(4) 154 .O ( 4) 149.7 ( 4) 152.0 (4) 150. 5( 4) 132.6( 4) 146.7( 4 ) 139.5( 4) 139.1 ( 4) 138. 4( 4) 138.1 (4) 137.8 (5) 138.2 ( 4) 149.0 (4) Tab.…”

Section: Rontgenstrukturanalyse Von 11 Und 19 *P)mentioning

confidence: 99%

Section: N-~l-[l-(phenylsulfonyl)-3-indolyl]vinyl~acetamid (9) Und N-unclassified

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Indole und Indolalkaloide, XXI. Darstellung von 4‐(Acetylamino)‐1,2,3,9a‐tetrahydrocarbazol‐Derivaten durch [4+2]‐Cycloadditionen an 3‐Indolyl‐enimiden und ‐enamiden

1986

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“…[6][7][8] Further developments in the field have been achieved during the synthesis of natural products containing aldehyde-derived en-Scheme 1. In particular, the reductive acylation of oximes, using Ac 2 O/pyridine, [10] Cr(OAc) 2 and Ti(OAc) 3 , [11] Fe, [12] Fe(OAc) 2 , [13] RuCl 2 /NaHSO 3 , [14] Et 3 P, [15] H 2 , [16] and CuI/NaHSO 3 [17] as reducing agents, provides easy access. be prepared.…”

Section: Introductionmentioning

confidence: 99%

The Synthesis of Ketone‐Derived Enamides by Elimination of HCN from Cyanoamides

2016

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Treatment of easily available ketone‐derived cyanoamides with NaOtBu leads to enamides in a simple, scalable, and inexpensive one‐step operation in good yield. Enamides not stabilized by conjugation or by inclusion in a ring can also be prepared. An E1cB mechanism consistent with all results and observations, is proposed. The Z geometry of the product enamide is highly favoured, and the regioselectivity can be directed by one′s choice of protecting group.

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“…8 In 1975 Barton et al demonstrated that ketoximes, as well as their O-acyl and O-alkyl derivatives, could be converted into secondary acetyl enamides in excellent yields by heating at reflux with acetic anhydride in pyridine. 9 A free radical mechanism was postulated for this transformation. In addition, it was found that treatment of ketoximes with acetic anhydride in the presence of stoichiometric amounts of metals such as Cr(II) and Ti(III) also affords the corresponding enamides.…”

mentioning

confidence: 99%

Preparation and Allylation of Enamides and Enecarbamates Generated via Iron(0) Reduction of Oximes and Derivatives

Sun¹,

Weinreb²

2006

Synthesis

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P r e p a r a t i o n a n d A l l y l a t i o n o f E n a m i d e s a n d E n e c a r b a m a t e s Abstract: Reductive acylation of oximes and oxime carbonates can be effected with iron powder in the presence of an acid chloride or a chloroformate to produce enamides or enecarbamates.Enamides have been widely used as intermediates in organic synthesis. For example, enamides are valuable precursors for generation of N-acyliminium ions, 1,2 and have also been utilized recently in asymmetric hydrogenation reactions to prepare N-acyl derivatives of chiral amines. 3 Enamides have been synthesized by a variety of methods, including the Curtius rearrangment, 4 by direct addition of amides to alkynes, 5 and by transition-metal-promoted coupling of vinyl halides with amides. 6 Another common method for the preparation of enamides is simply to Nacylate an imine with an acid halide or an acid anhydride. 7 However, this methodology is only practicable for synthesis of tertiary enamides derived from N-alkyl-or N-arylsubstituted imines due to the difficulty in condensing ammonia with aldehydes or ketones to form simple unsubstituted imines. 8In 1975 Barton et al. demonstrated that ketoximes, as well as their O-acyl and O-alkyl derivatives, could be converted into secondary acetyl enamides in excellent yields by heating at reflux with acetic anhydride in pyridine. 9 A free radical mechanism was postulated for this transformation. In addition, it was found that treatment of ketoximes with acetic anhydride in the presence of stoichiometric amounts of metals such as Cr(II) and Ti(III) also affords the corresponding enamides. More recently, Burk and coworkers reported that acetyl enamides can be prepared in moderate to good yields from ketoximes by heating at 70°C in toluene-acetic anhydride in the presence of inexpensive iron powder (Scheme 1). 10 In an improvement of this methodology, Zhang and Casalnuovo found that these reactions can be effected at room temperature if N,N-dimethylformamide is used as solvent, and also that the reaction is initiated by addition of a catalytic amount of chlorotrimethylsilane. 3g It might be noted that to date the methodology has only been applied to ketoximes derived from aryl or hindered ketones. 3g,10

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A simple synthesis of enamides from ketoximes

Cited by 60 publications

References 0 publications

Indole und Indolalkaloide, XXI. Darstellung von 4‐(Acetylamino)‐1,2,3,9a‐tetrahydrocarbazol‐Derivaten durch [4+2]‐Cycloadditionen an 3‐Indolyl‐enimiden und ‐enamiden

Indole und Indolalkaloide, XXI. Darstellung von 4‐(Acetylamino)‐1,2,3,9a‐tetrahydrocarbazol‐Derivaten durch [4+2]‐Cycloadditionen an 3‐Indolyl‐enimiden und ‐enamiden

The Synthesis of Ketone‐Derived Enamides by Elimination of HCN from Cyanoamides

Preparation and Allylation of Enamides and Enecarbamates Generated via Iron(0) Reduction of Oximes and Derivatives

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