Abstract:Durch Umsetzung von Carbonskurechloriden und Benzyliden-methylamin werden N-a-Halogenalkyl-carbonsaureamide gewonnen, die durch Alkoholyse bei Gegenwart tertitirer Amine in N-a-Alkoxyalkyl-carbonsaureamide fibergefuhrt werden. -Die aus Benzyliden-methylamin und CarbonsHurebromiden entstehenden Additionsprodukte reagieren hingegen mit einer zweiten Molekel Schiffscher Base unter Bildung leicht hydrolysierbarer, mesorneriestabilisierter Immonium-Oxonium-Salze.
“…Thiophene‐ and pyrrole‐fused imines 6 d and 6 e were also suitable substrates, as was benzylated imine 6 f , all forming the expected spirocycles 8 l / 9 l – 8 n / 9 n with generally good diastereoselectivity and in good yield. Acyclic imines, which are often avoided in related methods based on N‐ acyliminium ion chemistry due to their tendency to hydrolyse, are also well‐tolerated, with spirocyclic products 8 o / 9 o and 8 p / 9 p each isolated in good overall yields. The major diastereoisomer formed in each case was assigned based on 1 H NMR spectroscopy, and in the case of spirocycles 8 n and 8 o , confirmed by X‐ray crystallography (Scheme )…”
Heteroaromatic carboxylic acids have been directly coupled with imines using propylphosphonic anhydride (T3P) and NEt(iPr)2 to form azaspirocycles via intermediate N‐acyliminium ions. Spirocyclic indolenines (3H‐indoles), azaindolenines, 2H‐pyrroles and 3H‐pyrroles were all accessed using this metal‐free approach. The reactions typically proceed with high diastereoselectivity and 3D shape analysis confirms that the products formed occupy areas of chemical space that are under‐represented in existing drugs and high throughput screening libraries.
“…Thiophene‐ and pyrrole‐fused imines 6 d and 6 e were also suitable substrates, as was benzylated imine 6 f , all forming the expected spirocycles 8 l / 9 l – 8 n / 9 n with generally good diastereoselectivity and in good yield. Acyclic imines, which are often avoided in related methods based on N‐ acyliminium ion chemistry due to their tendency to hydrolyse, are also well‐tolerated, with spirocyclic products 8 o / 9 o and 8 p / 9 p each isolated in good overall yields. The major diastereoisomer formed in each case was assigned based on 1 H NMR spectroscopy, and in the case of spirocycles 8 n and 8 o , confirmed by X‐ray crystallography (Scheme )…”
Heteroaromatic carboxylic acids have been directly coupled with imines using propylphosphonic anhydride (T3P) and NEt(iPr)2 to form azaspirocycles via intermediate N‐acyliminium ions. Spirocyclic indolenines (3H‐indoles), azaindolenines, 2H‐pyrroles and 3H‐pyrroles were all accessed using this metal‐free approach. The reactions typically proceed with high diastereoselectivity and 3D shape analysis confirms that the products formed occupy areas of chemical space that are under‐represented in existing drugs and high throughput screening libraries.
a-Alkyl-A 1-pyrroline reagieren uber ihre Lithiumverbindungen mit Ketonen, Aldehyden und Estern zu 0-Hydroxy-bzw. 6 -Ketoalkylpynolinen. Bei der Umsetzung mit Alkylhalogeniden entstehen homologe a-Alkyl-A 1-pyrroline.
Addition of Lithiated A1-Pynolines to Carbonyl Derivatives and lukyl HalidesLithiated a-alkyl-A1-pyrrolines react with ketones, aldehydes and esters t o yield 0-hydroxy-and 6 -ketoalkylpyrrolines. Reaction with alkyl halides leads to homologous a-alkyl-A'-pyrrolines.
Die elektrophile Aminomethylierung von Ketonen und Aldehyden nach Munnich')ist eine bewahrte Methode zur Darstellung von Aminoalkoholen. Acyclische Irnine lassen sich nach Kuuffmann metallieren und uber das 2-Azaallylanion nucleophil an Ketone') als auch an ungesattigte Kohlenwas~erstoffe~) addieren.2-Alkyl-A 1-pyrroline reagieren nach unseren Untersuchungen als CH-acide Komponente mit 1 ,2-Dicarbonsaureestern4) und Alkincarb~nylverbindungen~) im Sinne
Lknnhardt und ObergrusbergerArch. Pharm.
“…Die Reaktion fuhrt uber die N-a-Halogenalkyl-carbonsameamide (1) [4], die rnit Zinntetrachlorid die N-Methyl-Nacylbenzaldiminium-Salze (2) bilden. Phenylacetylen reagiert dann in einer 1.4-Addition unter Bildung von (3).…”
Mols Base (Methylsulfinyl-Carbmion [2] oder t-Butylat) mit Methylenverbindungen zu Cyclopropanverbindungen urn. Mit Tetralon entsteht in (2), F p = 86,5-87,5 "C. a RY c c 1 4 CHC13 CHzCIz CI(CHZ)zC1 CHC13 Cl(CH2)zCl c c 1 4 CHCl, CHzCIz CI(CH2)zCl ( I ) , H . = <:&Is 12) Aus ( I ) und Acetophenon oder Acetessigester bilden sich 2-Benzoylcyclopropancarbons~ure-athylester (3)(Ausb. 60 z, Kp = 1 lO"C/O,t Torr; n' : = 1,5212; Dinitrophenylhydrazon: Fp : = 173-174 "C) bzw. 2-Acetylcyclopropan-1.2-dicarbon-s4ure-diathylester (4) (Ausb. 40 %; K p = 82-87 "C/O,l Torr; n:," = 1,4668).Beispiel: Zu einer Mischung aus 25 g Phosphoenolbrenztraubensaure-triathylester und 15 g cc-Tetralon laBt man bei einer Innentcniperatur von 45 "C unter Nz eine Losung von 2,5 NaH in 50 ml Dimethylsulfoxyd [2] tropfen. Man gieBt nach 30 min in 500 ml Wasser, extrahiert mit Chloroform und erhiilt (2) beim Aufarbeiten der Chloroformlosung. Reinigung durch Umkristallisieren aus Athanol oder durch Hochvakuumdestillation aus einem Sabelkolben (Badtemperattir 180 DC/O,Ol Torr). Die neue Cyclopropansynthese, die wohl iiber eine Michael-Addition gefolgt von einer 1.3-Eliminierung fuhrt, verlauft in den Fallen (2) und (3) stereospezifisch. Es entsteht nur ein Isomeres (2) (auch dunnschichtchroniatographisch ein-
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