Azomethin-ylide und ihre 1.3-dipolaren cycloadditionen

Stereochemistry of 1,3‐dipolar‐cycloaddition of 3,4‐dihydroisoquinoline‐ and 3,4‐dihydro‐carboline‐N‐methoxycarbonyl‐ and N‐phenacyl‐methylides with maleic and fumaric nitrile

“…At first Huisgen [16] applied this approach in the study of 1,3-dipolar cycloaddition of N-phenacyl-3,4-dihydro-isoquinolinium ylides. Despite the considerable advantages of this method in the next years it was relatively sparsely applied: only Tsuge et al used it also for the preparation of isoquinolinium ylides [17], then Pota ek [18] and S iwa [19] applied it for the synthesis of phenantridinium and benzo[h]napthyridinium ylides, respectively.…”

“…It is worth mentioning some other less direct synthetic routes, which were also applied for the preparation of nonstabilized cyclic azomethine ylides by Poissonnet (desylilation route [3]), and Novikov (difluoro-carbene addition route [20]) and for stabilized cyclic ylides by Grigg (dehydrogenation route [21]). The cited authors [3,[16][17][18][19][20][21] studied the 1,3-dipolar cycloaddition reactions of the so prepared cyclic azomethine ylides with activated olefines e.g. maleic imides, fumaric and maleic esters and even with fumaric nitrile [18], but none of them examined the cycloadditions of stabilized dihydro-isoquinoline and carboline ylides with maleic and fumaric nitriles and in most cases the investigations were not extended to thorough stereochemical studies applying one-and two dimensional NMR methodes.…”

New N-bridgehead heterocyclic compounds. I. Carbamoyl-substituted indolizines and benzoindolizines

“…4,5 In some cases aromatic indolizines were prepared by two-steps procedures, in which the initially formed tetrahydroindolizines or dihydroindolizines are dehydrogenated by treatment with suitable reagents. [6][7][8][9][10] By 1,3-dipolar cycloaddition reactions of the 4-methylpyridinium-, respectively isoquinolinium-carbamoylmethylides, generated in situ from the corresponding quaternary salts, with acrylonitrile and respectively with crotononitrile, in the presence of tetrapyridinecobalt(II)-dichromate, 11 , and respectively at δ 9,16 and δ 7.23 (for 32), were attributed to H-5 and H-6. The characteristic signals for methyl protons appeared at δ 2.75, respectively δ 3.88.…”

Reaction of 1-Alkylthioisoquinolinium Salts with Active Methylene Compounds.

“…The conventional methods for preparing the substituted pyrrolo[2,1-a]isoquinoline derivatives are either via Michael condensation of Reissert compounds, 4) or via 1,3-and 1,5-dipolar cycloaddition reactions. 5,6) In this paper, we report a novel method for the synthesis of a pyrrolo[2,1-a]isoquinoline skeleton using the cyclization of 2-benzyl-1-(substituted methylene) isoquinolines, which are readily prepared by the reaction of 2-benzyl-1-alkylthioisoquinolinium iodides with active methylene compounds.Reaction of 1-Alkylthioisoquinolinium Iodides with Active Methylene Compounds Initially, the reaction of active methylene compounds with isoquinolinium salts that have a methylthio group as a leaving group at the 1-position was examined under mild conditions in the presence of sodium hydride (Chart 2, Table 1). 2-Methyl-and 2-benzyl-1(2H)-thioisoquinolones (3, 7) 4) were prepared from 2-methyl-and 2-benzyl-1(2H)-isoquinolones (1, 8) 2) in excellent yields, respectively.…”

“…The conventional methods for preparing the substituted pyrrolo[2,1-a]isoquinoline derivatives are either via Michael condensation of Reissert compounds, 4) or via 1,3-and 1,5-dipolar cycloaddition reactions. 5,6) In this paper, we report a novel method for the synthesis of a pyrrolo[2,1-a]isoquinoline skeleton using the cyclization of 2-benzyl-1-(substituted methylene) isoquinolines, which are readily prepared by the reaction of 2-benzyl-1-alkylthioisoquinolinium iodides with active methylene compounds.…”