New Formation of Pyrrolizines by Intramolecular Cyclization of Phenacyl Substituted Tetrahydropyridines

Csuzdi, Emese; Pallagi, István; Jerkovich, Gyula; Sólyom, Sándor

doi:10.1055/s-1994-22876

Cited by 7 publications

(4 citation statements)

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“…Coordination of a Lewis acid to the carbonyl group of 15 gives V and V ‘. Carbon−carbon bond formation between the carbonyl carbon coordinated by the Lewis acid and the double bond occurs to form the six-membered cation VI , and the generated cation VI should be stabilized by an adjacent aryl group …”

Section: Resultsmentioning

confidence: 99%

Palladium-Catalyzed Asymmetric Allylic Substitution of 2-Arylcyclohexenol Derivatives: Asymmetric Total Syntheses of (+)-Crinamine, (−)-Haemanthidine, and (+)-Pretazettine

2004

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Much interest has been shown in Amaryllidaceae alkaloids as synthetic targets due to their wide range of biological activities. Over 100 alkaloids have been isolated from members of the Amaryllidaceae family; most of them can be classified into eight skeletally homogeneous groups. We have succeeded in the first asymmetric total syntheses of the crinane-type alkaloids (+)-crinamine (1), (-)-haemanthidine (2), and (+)-pretazettine (3). The starting cyclohexenylamine 14 was obtained from allyl phosphonate 11c by palladium-catalyzed asymmetric amination in 82% yield and with 74% ee. The product was recrystallized from MeOH. Interestingly, (-)-14 with 99% ee was obtained from the mother liquor (74% recovery). Intramolecular carbonyl-ene reaction of (-)-10 proceeds in a highly stereoselective manner to give hexahydroindole derivative 9 as the sole product. In the Lewis-acid-catalyzed carbonyl-ene reaction, an interesting rearrangement product, 20, was isolated in high yield. From 9, (+)-crinamine was synthesized. Thus, the asymmetric total synthesis of (+)-crinamine was achieved in 10 steps from 11c, and the overall yield is 19%. The total synthesis of (-)-haemanthidine was also achieved from 9 by a short sequence of steps.

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Section: Resultsmentioning

confidence: 99%

Palladium-Catalyzed Asymmetric Allylic Substitution of 2-Arylcyclohexenol Derivatives: Asymmetric Total Syntheses of (+)-Crinamine, (−)-Haemanthidine, and (+)-Pretazettine

2004

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“…Recently, a very large family of natural products such as alkaloides containing pyrrolizine systems which are isolated from plants, insects, animals, marine organisms and microbes having biological activities occupy an important place in the realm of natural and synthetic organic chemistry 4 . Although there are some reports regarding the chemistry and synthesis of such compounds, [5][6][7][8][9][10][11] in view of the above observations, and as part of our program that involves the synthesis of new heterocyclic compounds, 12,13 we report here the preparation of new phosphorus compounds and dimethyl 1-(trifluoromethyl)-3H-pyrrolizine-2,3-dicarboxylate in good to excellent yields.…”

Section: Introductionmentioning

confidence: 95%

Synthesis of dimethyl-1-(trifluoromethyl)-3H-pyrrolizine-2,3-dicarboxylate using phosphorus compounds

Kalantari¹,

Islami²,

Hassani³

et al. 2006

Arkivoc

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A general and practical route for the synthesis of phosphorus compounds containing trifluoromethyl or trichloromethyl groups by a one-pot condensation triphenylphosphine and dialkyl acetylenedicarboxylate in the presence of an NH-acid such as 2,2,2-trifluoro-1-(1H-pyrrol-2-yl)ethanone or 2,2,2-trichloro-1-(1H-pyrrol-2-yl)ethanone is described. The product obtained from the fluorinated compound undergoes an intramolecular Wittig reaction in boiling THF. This method offers a simple procedure for the preparation of dimethyl 1-(trifluoromethyl)-3H-pyrrolizine-2, 3-dicarboxylate.

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“…In view of the intense interest in these compounds and the scarcity of natural samples, a number of new methodologies and strategies have been developed towards their synthesis. [5][6][7][8] We have recently reported that 1-ethylthio-3-iminopyrrolizines, the products of intramolecular cyclization of 2-(1-ethylthio-2-cyanoethenyl)pyrroles, 9 when treated with secondary amines in methanol, readily exchange their ethylthio group for the amine moiety, thus forming the corresponding 1-aminopyrrolizines. 10 In the presence of water, the direction of the reaction of 1-ethylthio-3-iminopyrrolizines with secondary amines is determined by the nature of the substituents in the pyrrolizine cycle: pyrrolizine-2-carbonitriles exchange its ethylthio group for an amine residue only, whereas pyrrolizine-2-carboxamides undergo ring-opening to give the corresponding 2-(1-amino-2-carbamoyl-2-cyanoethenyl)pyrroles.…”

Section: Introductionmentioning

confidence: 99%

The reaction of 1-ethylthio-3-iminopyrrolizines with hydroxylamine. A new synthesis of 3-aminoisoxazoles

Собенина¹,

Drichkov²,

Михалева³

et al. 2005

Arkivoc

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New Formation of Pyrrolizines by Intramolecular Cyclization of Phenacyl Substituted Tetrahydropyridines

Cited by 7 publications

References 0 publications

Palladium-Catalyzed Asymmetric Allylic Substitution of 2-Arylcyclohexenol Derivatives: Asymmetric Total Syntheses of (+)-Crinamine, (−)-Haemanthidine, and (+)-Pretazettine

Palladium-Catalyzed Asymmetric Allylic Substitution of 2-Arylcyclohexenol Derivatives: Asymmetric Total Syntheses of (+)-Crinamine, (−)-Haemanthidine, and (+)-Pretazettine

Synthesis of dimethyl-1-(trifluoromethyl)-3H-pyrrolizine-2,3-dicarboxylate using phosphorus compounds

The reaction of 1-ethylthio-3-iminopyrrolizines with hydroxylamine. A new synthesis of 3-aminoisoxazoles

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