Regioselective Anionic [3+2] Cyclizations of Imidazole Dinucleophiles with Oxaldiimidoyl Dichlorides − A Combined Experimental and Theoretical Study

Langer, Peter; Wuckelt, Jörg; Döring, Manfred; Schreiner, Peter R.; Görls, Helmar

doi:10.1002/1099-0690(200106)2001:12<2245::aid-ejoc2245>3.0.co;2-c

Cited by 16 publications

(13 citation statements)

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“…[19] The triethylamine-mediated cyclization of oxaldiimidoyl dichlorides with 2-aminobenzimidazole (44) afforded the 3H-imidazo[1,2-a]benzimidazoles 45. [20] Regioselective S,N-cyclization and formation of the 2,3-dihydrothiazolo[3,2-a]benzimidazoles 47 was observed on treatment of oxaldiimidoyl dichlorides with the dianion of 2-mercaptobenzimidazole (46) (generated by nBuLi). [20,21] In contrast, the novel diazabicyclo[2.2.1]heptanones 49 were regioselectively formed by N,N-cyclization of oxaldiimidoyl dichlorides with the dianion of 2-hydroxybenzimidazole 48 (generated with Na[N(SiMe 3 ) 2 ]).…”

Section: Heterocyclic 13-dinucleophilesmentioning

confidence: 99%

“…[20] Regioselective S,N-cyclization and formation of the 2,3-dihydrothiazolo[3,2-a]benzimidazoles 47 was observed on treatment of oxaldiimidoyl dichlorides with the dianion of 2-mercaptobenzimidazole (46) (generated by nBuLi). [20,21] In contrast, the novel diazabicyclo[2.2.1]heptanones 49 were regioselectively formed by N,N-cyclization of oxaldiimidoyl dichlorides with the dianion of 2-hydroxybenzimidazole 48 (generated with Na[N(SiMe 3 ) 2 ]). [20] This unexpected regioselectivity is presumably kinetically controlled, as according to AM1 calculations the isomeric O,Ncyclization product is thermodynamically favored by 22.2 kcal/mol.…”

Section: Heterocyclic 13-dinucleophilesmentioning

confidence: 99%

“…[20] Use of 3-amino-1,2,4-triazole (52) resulted in regioselective formation of the 5H-imidazo[2,1-c]-1,2,4-triazoles 53-A and 53-B (A/B ϭ 5:1). [22] The regioselectivity can be explained by the higher thermodynamic stabilities …”

Section: Heterocyclic 13-dinucleophilesmentioning

confidence: 99%

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Efficient Synthesis of Nitrogen Heterocycles by Cyclization of Bis(nucleophiles) with Oxaldiimidoyl Dichlorides

Langer

Döring²

2002

Eur. J. Org. Chem.

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Section: Heterocyclic 13-dinucleophilesmentioning

confidence: 99%

Section: Heterocyclic 13-dinucleophilesmentioning

confidence: 99%

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Efficient Synthesis of Nitrogen Heterocycles by Cyclization of Bis(nucleophiles) with Oxaldiimidoyl Dichlorides

Langer

Döring²

2002

Eur. J. Org. Chem.

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“…Computational Methods: Details pertaining to the computational methods are given in the preceding paper. [6] Geometries were fully optimized at the semiempirical AM1 level of theory, using analytical gradients as implemented in the Gaussian 98 program package. Harmonic vibrational frequencies were computed to ascertain the nature of all stationary points; the number of the imaginary modes is 0 for minima and 1 for the transition structures.…”

Section: Preparation Of Nnј-bis(5-methylisoxazol-3-yl)ethanediamide mentioning

confidence: 99%

“…In the preceding paper we studied [6] the regioselectivity of cyclizations of 2-methyl-, 2-amino-, 2-mercapto-and 2-hydroxybenzimidazoles with oxaldiimidoyl dichlorides. [7] These reactions afforded a variety of structurally interesting and biologically relevant benzimidazoles and diazabicyclo[2.2.1]heptanones.…”

Section: Introductionmentioning

confidence: 99%

Regioselective Anionic [3+2] Cyclizations of Isoxazole, Pyrazole and 1,2,4-Triazole Dinucleophiles − Efficient Synthesis of 2,4-Dihydroimidazo[4,5-b]quinoxalines, 3H-Imidazo[1,2-b]pyrazoles and 5H-Imidazo[2,1-c][1,2,4]triazoles

et al. 2001

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Regioselective Synthesis of Heterospirocyclic Isobenzofuranones and Medium-Sized Lactones by Multiple Anion Capture Reactions of 1,3-Dianions

2001

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The multicomponent reaction of 1,3-dianions with ketones and oxalic acid dichloride or diethylmalonic dichloride afforded six-to eight-membered lactones. Treatment of the dianion of 3-acetylindole with benzophenone and diethylmaDomino and multi-component reactions have found widespread applications in organic synthesis. [1] Multiple anion capture reactions involve attack of a carbanion on a relais species to form an intermediate which is subsequently reacted with an electrophile. Recent examples include the reaction of carbon nucleophiles with allenes and subsequent cyclization with acrylates, [2] and reactions involving isocyanates [3] or allenyl isothiocyanates as the relais species. [4] Multiple anion capture reactions involving nitriles as the relais species have been observed in the reaction of bislithiated 2,3-methylbutadiene with benzonitrile, [5] and in the 1,4-addition of nitriles to (butadiene)zirconocene. [6] In the course of our program [7] directed at the development of cyclization reactions of dianions [8] and dianion equivalents with dielectrophiles, we have recently studied nitriles as relais species in reactions of 1,3-dianions [9aϪ9c] and dilithiated allenes. [9d] We wish to report full details of our studies related to multiple anion capture reactions of 1,3-dianions with ketones and carboxylic acid dichlorides. [10] These reactions provide an efficient access to medium-sized lactones and novel heterospirocyclic isobenzofuranones. [11Ϫ13] Results and Discussion Synthesis of Lactones and Silyl EthersChlorosilanes were used in our first experiments aimed at demonstrating the concept of multiple anion capture reactions of dianions with ketone relais species. The dianion [14] of 1,1-diphenylacetone 1 was generated by treatment of 1 with potassium hydride and nBuLi. The dianion was condensed in situ with one equivalent of benzophenone 2a to give the dianionic intermediate A by regioselective attack of the terminal carbon atom of the dianion at the carbonyl group. Owing to steric and electronic reasons (delocaliz- [a] 1511 lonic dichloride resulted in the formation of a cyclic 1,3,5-triketooctene. The reaction of 1,3-dianions with ketones and phthalic dichloride resulted in the formation of heterospirocyclic isobenzofuranones rather than of medium-sized rings.ation of the negative charge through the phenyl rings), the carbon attached to the phenyl groups is less nucleophilic than the terminal carbon of the dianion. Subsequent addition of Me 3 SiCl gave the open-chain silyl ethers 3a and 3b in high yields (Scheme 1). Reaction of intermediate A with dichloro-diphenylsilane afforded the 1,3,2-dioxasilinane 3c in 76% yield. Scheme 1. Reaction of the dianion of 1,1-diphenylacetone with benzophenone and chlorosilanes Three-component cyclizations of dianions with ketones and dicarboxylic acid dichlorides were studied next. These reactions can, in principle, result in the formation of different regioisomeric cyclization products, as well as macrocyclic or polymeric products. In fact, we have found that...

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Regioselective Anionic [3+2] Cyclizations of Imidazole Dinucleophiles with Oxaldiimidoyl Dichlorides − A Combined Experimental and Theoretical Study

Cited by 16 publications

References 50 publications

Efficient Synthesis of Nitrogen Heterocycles by Cyclization of Bis(nucleophiles) with Oxaldiimidoyl Dichlorides

Efficient Synthesis of Nitrogen Heterocycles by Cyclization of Bis(nucleophiles) with Oxaldiimidoyl Dichlorides

Regioselective Anionic [3+2] Cyclizations of Isoxazole, Pyrazole and 1,2,4-Triazole Dinucleophiles − Efficient Synthesis of 2,4-Dihydroimidazo[4,5-b]quinoxalines, 3H-Imidazo[1,2-b]pyrazoles and 5H-Imidazo[2,1-c][1,2,4]triazoles

Regioselective Synthesis of Heterospirocyclic Isobenzofuranones and Medium-Sized Lactones by Multiple Anion Capture Reactions of 1,3-Dianions

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