Tandem cyclisation and [2,3]-Stevens rearrangement to 2-substituted pyrrolidines

Smith, Stephen C.; Bentley, Philip D.

doi:10.1016/s0040-4039(01)02286-9

Cited by 19 publications

(1 citation statement)

References 15 publications

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“…Selected examples of prolines C,D obtained from salts A,B are presented in Scheme 1. [13,16] Moreover, the [2,3] Sommelet-Hauser rearrangement of ylides generated from proline derived N-(substituted)allyl ammonium salts is one of the steps in the synthesis of stemofoline derivatives, [19] amathaspiramide F, [20] cephalotaxine, [21] (�)-strictamine [22] and (À )-cephalezomine G. [23] What is important, in all cases rearrangement of ylides generated from proline-derived ammonium salts affords derivatives of proline esters, substituted at C-2 with benzyl, [12,13,16] allyl [12,[15][16][17][18] or aryl [12,14] group. To the best of our knowledge, there are no examples of the rearrangements of these ylides that occur via ring-enlargement.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of 2‐Aryl‐N‐(EWG‐methyl)‐N‐methylpyrrolidinium Salts as Precursors of Ylides Entering the [1,2] Stevens Rearrangement

et al. 2021

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N-(EWG-CH2 )-N-methyl-2-phenylpyrrolidinium (EWG -electronwithdrawing group) salts were obtained in two different ways. N-(EWG-CH 2 )-2-phenylpyrrolidines were quaternized with iodomethane, dimethylsulfate or methyl trifluoromethanesulfonate forming pyrrolidinium iodides, methylsulfates and triflates. The counterion exchange in the methylsulfates was carried out yielding respective tetrafluoroborates. The second method was based on the quaternization of N-methyl-2-phenylpyrrolidine with methyl α-halogenoacetate or phenacyl bromide. All listed salts were oily and formed in high yields as mixtures of diastereoisomers, with cis or trans isomer predominating, depending on the method applied. The effect of the counterion present in the obtained salts was analyzed. Ylides generated from these salts in different base/solvent systems afforded products of the [1,2] Stevens rearrangement, 2-EWG-1-methyl-3-phenylpiperidines, with the trans isomers predominating, in moderate to good yields. In case of the [1,2] shift, the yields of respective products depended on EWG present in the substrate (methoxycarbonyl, acetyl, dimethylcarbamoyl and benzoyl).

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Section: Introductionmentioning

confidence: 99%

Synthesis of 2‐Aryl‐N‐(EWG‐methyl)‐N‐methylpyrrolidinium Salts as Precursors of Ylides Entering the [1,2] Stevens Rearrangement

et al. 2021

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Two Pyrrolo[1,2‐a]azepine Type Alkaloids from Stemona collinsaeCraib: Structure Elucidations, Relationship to Asparagamine A, and a New Biogenetic Concept of Their Formation

Seger

Mereiter

Kaltenegger

et al. 2004

Chemistry & Biodiversity

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The alkaloids 1',2'-didehydrostemofoline (2) and 2'-hydroxystemofoline (3) from Stemona collinsae Craib (Stemonaceae) were studied by X-ray crystallography and NMR spectroscopy, and they are compared with the parent compound stemofoline (1). The X-ray analysis of the CH2Cl2 solvate of 2'-hydroxystemofoline (3) allowed the determination of the absolute configuration of this compound unequivocally, whereas optical rotation was used to infer the absolute configuration of 1',2'-didehydrostemofoline (2). Based on these results, it is shown that asparagamine A isolated from Asparagus racemosus Willd. (Asparagaceae) is identical to 1',2'-didehydrostemofoline obtained from S. collinsae Craib, and that the reported plant source of asparagamine A was most likely a Stemona species. In the context of the current investigations, a novel concept on the biosynthesis of Stemona alkaloids has been worked out and is presented here.

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One or More CC Bond(s) Formed by Substitution: Substitution of Carbon–Nitrogen, –Phosphorus, –Arsenic, –Antimony, –Boron, –Silicon, –Germanium, and –Metal Functions

Kouklovsky

2005

Comprehensive Organic Functional Group Transformations II

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Tandem cyclisation and [2,3]-Stevens rearrangement to 2-substituted pyrrolidines

Cited by 19 publications

References 15 publications

Synthesis of 2‐Aryl‐N‐(EWG‐methyl)‐N‐methylpyrrolidinium Salts as Precursors of Ylides Entering the [1,2] Stevens Rearrangement

Synthesis of 2‐Aryl‐N‐(EWG‐methyl)‐N‐methylpyrrolidinium Salts as Precursors of Ylides Entering the [1,2] Stevens Rearrangement

Two Pyrrolo[1,2‐a]azepine Type Alkaloids from Stemona collinsaeCraib: Structure Elucidations, Relationship to Asparagamine A, and a New Biogenetic Concept of Their Formation

One or More CC Bond(s) Formed by Substitution: Substitution of Carbon–Nitrogen, –Phosphorus, –Arsenic, –Antimony, –Boron, –Silicon, –Germanium, and –Metal Functions

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