Aromatic Aza-Claisen Rearrangement of Arylpropargylammonium Salts Generated in situ from Arynes and Tertiary Propargylamines

The charge-accelerated aza-Claisen rearrangement of ammonium salts serves as a key step in the construction of complex nitrogen-containing molecules. However, much less attention has been paid to the aromatic aza-Claisen rearrangement than to the aliphatic one. Herein, we report an unprecedented aromatic aza-Claisen rearrangement of arylpropargylammonium salts, generated in situ from arynes and tertiary propargylamines, delivering structurally diverse 2-propargylanilines in moderate to good yields with high regioselectivity. This rearrangement proceeds in the absence of strong bases or transition metals, is compatible with moisture and air, tolerates a wide variety of functional groups, and is amenable to forming 11- to 13-membered heterocycles with a triple bond. The 2-propargylaniline products were treated with aluminum chloride in ethanol to afford multisubstituted indoles in moderate to excellent yields. Finally, a series of deuterium-labeling experiments was performed to elucidate the reaction mechanism.     

A new synthesis of the linearly fused [1,2,4]triazolo[1,5-b]isoquinoline ring. Observation of an unexpected Dimroth rearrangement

A new and general synthesis of the linearly fused [1,2,4]triazolo[1,5-b]isoquinoline ring system starting from 2,3-diaminoisoquinolinium salts has been elaborated. Starting compounds bearing an alkyl group in position 4 easily reacted with aldehydes to yield the cyclized products. In the case of a lack of electron donating group in position 4 (e.g., unsubstituted or 4-cyano substituted diamino derivatives) a Dimroth rearrangement took place under the same reaction conditions to yield 3-isoquinolylhydrazones. The mechanism of this unexpected transformation has been verified by isotope labelling experiments. Clarification of the reaction mechanism allowed finding proper reaction conditions to eliminate the rearrangement route, and thus, to perfect successful ring closure to the fused triazoles.     

Stevens Rearrangement of Ammonium Salts Containing 3-Methyl-3-ethoxycarbonylbutanon-2-yl Group

Ammonium salts containing alongside 3-methyl-3-ethoxycarbonylbutanon-2-yl also 2-alkenyl or benzyl groups under the treatment with Na₂CO₃·10H₂O afford products resulting from Stevens rearrangement. In the mentioned salts the ketoester group on treatment with sodium ethylate suspension in ether or benzene suffers partial or total acid cleavage, and then the Stevens 3,2-rearrangement takes place.     

Cycloaddition in Condensed Isoindoles. 2. Method for Obtaining New Derivatives of 2-Phenylpyridine

The reaction of pyrido[2,1-a]isoindole with maleimide derivatives has been investigated. A new rearrangement has been found, the products of which are 2-[2'-(1-R-2,5-dioxopyrrolidinidene)-2'-(1-R-2,5-dioxopyrrolidinyl)methyl]phenylpyridines. A probable mechanism for the rearrangement has been proposed. The existence of atropoisomerism for the compounds obtained has been demonstrated by ¹H NMR spectra.     

Cyclodimerization of the Stevens Rearrangement Products from 4-Alkoxy-2-butynyl(alkoxycarbonylmethyl)dimethyl-ammonium Salts into Cyclohexene Derivatives

4-Alkoxy-2-butynyl(alkoxycarbonyl)dimethylammonium salts undergo 3,2-Stevens rearrangement by the action of the corresponding sodium alkoxides. Hydrolysis of the rearrangement products with dilute hydrochloric acid gives 3-alkoxy-2-oxo-3-pentenoic acid esters which are converted into 3-methylene-2-oxo-4-pentenoates via 1,4-elimination of alcohol. [2 + 4]-Cyclodimerization of 3-methylene-2-oxo-4-pentenoates leads to 1,4-bis(alkoxalyl)-4-vinylcyclohexenes.     

Stevens rearrangement of ammonium salts containing 2-propynyloxy or tert-butoxycarbonylmethyl groups

The Stevens rearrangement of ammonium salts containing 2-alkenyl, 2-alkynyl, or benzyl groups along with 2-propynyloxy or tert-butoxycarbonylmethyl was studied. Under the action of a suspension of sodium phenolate in benzene the salts containing a 2-propynyloxycarbonylmethyl group form 2-propynyl esters of 2-dialkylamino-4-pentenoic acids, whereas with sodium methylate as the basic reagent, rearrangement is preceded by an almost complete transesterification. The salts containing a tert-butoxycarbonylmethyl group undergo almost no transesterification under the action of sodium methylate. The tert-butyl fragment in the ester group of the salt with a benzyl group exerts a fairly strong effect on the regiochemistry of the rearrangement and on the prototropic isomerization of the 3,2-Stevens rearrangement of the salts with 2-butynyl or 3-phenyl-2-propynyl groups.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1321–1326.Original Russian Text Copyright © 2004 by Babakhanyan, Ovakimyan, Grigoryan, Kocharyan.This revised version was published online in April 2005 with a corrected cover date.     

Unexpected ring transformation to pyrrolo[3.2-b]pyridine derivatives. Fused azolium salts. 22

2-Arylsulfanyl and 2-benzylsulfanylpyridinium N-arylimides (2) easily prepared from 3-aryltetrazolopyridinium salts (1) with aryl and benzylthiolates, respectively, reacted with various dipolarophiles yielding cycloadducts that underwent transformation to give tetrahydropyrrolo[3,2-b]pyridines (5, 6, and 8) in good yields. A similar rearrangement (formation of 15) was also observed in the case of parent derivatives being unsubstituted in position 2 (12). The abscence of any significant solvent effect, comparison of the sulfur and non-sulfur analogues, as well as the stereoselective nature of the observed ring transformation seem to support a sigmatropic mechanism. Structure elucidation of the products has been carried out by single-crystal X-ray diffraction and (1)H NMR experiments.     

Synthesis and transformations of polyhedral compounds 12. Stevens rearrangement in the azaadamantane series

Some quaternary salts of 1,3-diaza- and 1,3,5-triazaadamantanes undergo the Stevens rearrangement to give derivatives of the corresponding 1,4-diaza- and 1,3,6-triazahomoadamantanes. The structures of the rearrangement products were proved by IR, PMR, and mass spectroscopy and x-ray diffraction analysis (XDA).See [1] for Communication 11.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 669–673, May, 1991.     

Rearrangements of the aminoalkylation products of tetrahydro-2H-1,3-oxazine-2-thione

The nature of the compounds afforded by the rearrangement of the aminopropylation and aminoethylation products of tetrahydro-2H-1,3-oxazine-2-thione (I) has been investigated. In both instances compounds that can be considered to result from ring opening at either the C-O or C-S bond of a hypothetical bicyclic intermediate of structure IV were obtained. The compounds required for identification of the rearrangement products have been prepared by the reaction of the 2-methylthio derivatives of 2-thiazoline, 5,6-dihydro-4H-1,3-thiazine, and 5,6-dihydro-4H-1,3-oxazine with the appropriate hydroxyalkylamine or mercaptoalkylamine.     

Stevens Rearrangement of Anilinium Salts By the Action Sodium Carbonate Hexahydrate

Anilinium salts containing an allyl-like group together with various functionally substituted receiving groups undergo Stevens rearrangement by the action of sodium carbonate hexahydrate in the absence of a solvent. As a result, both N-methylaniline derivatives and nucleophilic substitution products are formed.     

Rh(II)-catalyzed [2,3]-sigmatropic rearrangement of sulfur ylides derived from N-tosylhydrazones and sulfides

In this paper, Rh₂(OAc)₄-catalyzed [2,3]-sigmatropic rearrangement of sulfur ylides derived from N-tosylhydrazones and sulfides is reported. A series of tosylhydrazones derived from aldehydes were successfully used for [2,3]-sigmatropic rearrangement by reaction with either allylic phenyl sulfides or propargyl phenyl sulfides. The reaction conditions were optimized and afforded the products in moderate to good yields. In addition, a novel and convenient approach for the synthesis of cyclobutenones and cyclopropanes has been developed through direct oxidation of the rearrangement products.     

Solid-phase rearrangement of aminals of 5-halofurfurals to 5-N,N-dialkylamino-furfurlyidene-N,N-dialkylimmonium salts

Aminals of 5-halofurfurals (products of the reaction of 5-halofurfurals with 2 moles of secondary amines) in the solid phase undergo rearrangement to 5-N,N-dialkylaminofurfurylidene-N,N-dialkylimmonium salts. The kinetics of the reaction were studied. A mechanism for the reaction is proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1468–1470, November, 1982.     

Reactions of thioquinanthrene with sodium alkanethiolates. The smiles rearrangement of diquinolinyl sulfides

Reactions of thioquinanthrene 1 with sodium alkanethiolates or S-alkylisothiouronium salts (in the presence of sodium hydroxide) at 70° in DMSO or DMF yielded 4,4′-dialkylthio-3,3′-diquinolinyl sulfides 3 , which were results of the S-S type of the Smiles rearrangement of primary reaction products - sodium 3-quinoline-thiolates 6. When the reactions were carried out at 20° the products were 3′,4-dialkylthio-3,4′-diquinolinyl sulfides 2.     

Unexpected Formation of 5‐Nitro‐1H‐benzimidazoles by Nucleophilic Recyclization of 1‐Methyl‐5‐nitropyridinium Salts

The synthesis of substituted 5‐nitro‐2‐phenyl‐1H‐benzimidazoles has been described via domino anionic process rearrangement of 3‐benzoylamino‐1,2‐dimethyl‐5‐nitropyridinium salts in the presence of NaOH water–alcohol solution. Substituted N‐benzoyl‐o‐phenylenediamines was obtained via recyclization of 3‐benzoylamino‐1,2‐dimethyl‐5‐nitropyridinium salts in the presence of aqueous methylamine solution.     

Intramolecular 1,5-Hydride Transfer in Rearrangements of Ammonium Salts Containing Alkoxycarbonylmethyl and 4-Penten-2-ynyl Groups

The Stevens 3,2 rearrangement of dialkylammonium salts containing, along with 4-penten-2-ynyl, an alkoxycarbonylmethyl group, gives mostly hydrogenated products, with simultaneous dealkylation and aldehyde formation. On acid treatment enamine amino esters give keto esters or their further transformation product, 4-ethyl3-hydroxy-5-methyltetrahydrofuran-2-one.     

A divergent synthesis of substituted 2-aminoimidazoles from 2-aminopyrimidines

A new divergent and efficient synthesis of substituted 2-aminoimidazoles 5 and 6 has been developed starting from the readily available 2-aminopyrimidines 1 and alpha-bromocarbonyl compounds 2, using conventional heating or microwave irradiation. Thus, the cleavage of 1,2,3-substituted imidazo[1,2-a]pyrimidin-1-ium salts 4 with hydrazine or secondary amines led to 1,4,5-trisubstituted 2-aminoimidazoles 5, when the hydrazinolysis of 2-hydroxy-2,3-dihydro-1H-imidazo[1,2-a]pyrimidin-4-ium salts 3, followed by a novel Dimroth-type rearrangement, resulted in formation of 2-amino-1H-imidazoles 6. The relevant pathway of transformations was identified by characterization of the intermediates.     

X-ray structural investigation of the products of ring closure of 2-alkenylthiopyridines upon treatment with mercury iodide

The products of the reaction of 2-alkenylthiopyridines with mercury iodide have been studied by single crystal X-ray diffraction. It has been demonstrated that the products are organomercury derivatives of salts of 2,3-dihydrothiazolo[3,2-a]pyridinium.     

Recyclization of 3-alkyl- and 1,3-dialkylisoquinolinium salts to naphthylamines

3-Methyl- and 3-benzylisoquinolinium salts undergo rearrangement to 2-alkylaminonaphthalenes under the influence of alcohol solutions of alkylamines. The rearrangement of 1,3-dimethyl- and l-methyl-3-benzylisoquinolinium salts leads to both 1- and 2-alkylaminonaphthalenes with predominance of the former.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1272–1277, September, 1980.     

二价钌催化的金属卡宾经由的硫叶立德[2,3]-σ重排反应研究

报道烯(炔)基硫醚与α-重氮羰基化合物, 在[RuCl₂(p-cymene)]₂催化下, 经由金属卡宾发生硫叶立德[2,3]-σ重排反应(Doyle-Kirmse反应). 在Ru(II)作用下, α-重氮羰基化合物与烯丙基硫醚的反应以较好收率生成相应的[2,3]-σ重排产物高烯丙基硫醚. 同样条件下与炔丙基硫醚的反应则生成[2,3]-σ重排产物联烯和呋喃衍生物, 后者是联烯进一步在Ru(II)作用下重排的产物.     

Gold-catalyzed transannular [4+3] cycloaddition reactions

In the presence of a catalytic amount of Au(I) and Ag(I) salts, the 14-membered furanophane II with an allene function located across the ring undergoes both a transannular [4+3] and [4+2] cycloaddition. Secondary rearrangement products containing a tricyclic ring system were isolated when the catalyst was PtCl₂.