Intramolecular 1,5-Hydride Shift in Products of Stevens 3,2-Rearrangement of Ammonium Salts Containing 3-Phenyl-2-propynyl Group

In products of Stevens 3,2-rearrangement of ammonium salts containing alongside alkoxycarbon- ylmethyl also 3-phenyl-2-propynyl group an intramolecular 1,5-hydride shift is observed resulting in immonium salts which transform into aminoesters of enamine structure. The hydrolysis of the latter provides the lower aliphatic aldehydes and the corresponding aminoesters. An acid treatment of the reaction mixture affords a mixture of hydrogenated and nonhydrogenated esters of α-ketoacids originating from the mixture of 1,3-diene aminoesters. At treating with concn. HCl of the obtained mixture the nonhydrogeneted ketoester undergoes cyclization into 4-methyl-3-phenyl-2-buten-1,4-olide.     

Formation of furan derivatives in the course of the Stevens rearrangement of ammonium salts containing 4-allyloxy(phenoxy)-2-butynyl group

Ammonium salts containing phenacyl group in combination with 4-allyloxy(phehoxy)-2-butynyl group, when treated with a suspension of potassium hydroxide in benzene, undergo the 3,2-Stevens rearrangement with the formation of allenic amino ketones which under the reaction conditions give the furan derivatives.     

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.     

Synthesis of Pyridazinone Derivatives

The reaction of methyl esters of 3-methyl-2-oxo- and 2-oxo-3-phenyl-3-pentenoic acids with hydrazine hydrate and phenylhydrazine was used to synthesize new pyridazinone derivatives. These products are formed through intermediate hydrazides with subsequent cyclization. 4-Hydroxy-3-oxotetrahydropyridazines are mainly formed using equimolar amounts of the starting reagents, while the corresponding hydrazones of 3,4-dioxohexahydropyridazines are formed in the case of a two-fold excess of hydrazine hydrate or phenylhydrazine. Evidence was obtained indicating the existence of a keto–enol tautomerism for 4-hydroxy-3-oxopyridazines.     

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.     

Cyclodimerization of 3,2-Stevens rearrangement products of 1,9-bisammonium salts containing a 5-oxanonane-2,7-diyne-1,9-diyl group

1,9-Bisdimethylammonium salts containing a 5-oxanonane-2,7-diyne-1,9-diyl along with alkoxycarbonylalkyl group, undergo double 3,2-Stevens rearrangement under the action of corresponding sodium alcoholates to form allene diamino esters whose prototropic isomerization under the action of dilute HCl gives rise to diketo diesters. The latter undergo 1,4-alcohol elimination under the reaction conditions and yield diene keto esters that cyclodimerize into cyclohexene derivatives. The bisammonium salt with a cyanomethyl group rearranges to form an allene dinitrile, which isomerizes into a diene compound.     

Synthesis of Allyl 2-Dialkylamino-4-pentenoates and Their Analogs via Stevens Rearrangement

Stevens rearrangement of ammonium salts containing an allyloxycarbonylmethyl group in benzene in the presence of sodium phenoxide yields allyl 2-dialkylamino-4-pentenoates. The rearrangement in the presence of sodium methoxide is accompanied by transesterification to afford methyl 2-dialkylamino-4-pentenoates.     

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.     

Stevens rearrangement of unsaturated ammonium salts. Synthesis of substituted furans

Ammonium salts bearing but-2-ynyl and phenacyl or 2-(naphth-2-yl)-2-oxoethyl moieties at the nitrogen atom underwent Stevens rearrangement to form substituted furan-3-amines. Quaternization of the latter afforded appropriate iodomethylates.