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New Thiocarbonyl Ylides Derived from 3,3-Dichloro-2,2,4,4-tetramethylcyclobutanethione; Generation and Reactions

100%

Woźnicka M. , Rutkowska M. , Mlostoń G. , Majchrzak A. , Heimgartner H.

2006

tom Vol. 80, nr 10

1683-1693

Trapping of thiocarbonyl ylides with NH-azoles; A novel route to N-substituted azoles

88%

Mlostoń G. , Gendek T. , Heimgartner H.

1998

tom Vol. 72, nr 1

66-72

Thermal decomposition of 2,5-dihydro-1,3,4-thiadiazoles (1) in the presence of imidazole, pyrazole, 3-phenylpyrazole, and 1,2,4-triazole, respectively, yielded S,N-acetals of type 4. Interception of initially formed thiocarbonyl ylide 2 by the NH-azole is proposed as the reaction mechanism. Treatment of the S,N-acetals 4 with Raney-Ni gave N-substituted azole 6.

A novel type of ring closure of amino-substituted thiocarbonyl ylides

88%

Romański J. , Mlostoń G. , Linden A. , Heimgartner H.

1999

tom vol. 73 nr 3

475-485

The reaction of 4,4-dimethyl-1,3-thiazole-5(4H)-thiones 7a-c with dimethyl 2-diazo-3-(phenyloamino)butanoate (2), prepared from dimethyl fumarate and phenyl azide, in toluene at 800C yielded mixtures of dimethyl 2-(4,5-dihydro-4,4-dimethyl-1,3-thiazol-5-ylidene)-3-(N-phenylamino)butanedioates of type 11 and four diastereoisometric 4,4-dimethyl-9-phenyl-1,6-dithia-3,9-diazaspiro[4,4]non-2-ene-7,8-dicarboxylates of type 12. The formation of the products of type 12 is rationalized by a novel cyclization of intermediate thiocarbonyl ylides 9. The structures of cis-12a, cis-12c, and trans-12c were established by X-ray crystallography.

Chemoselectivity of the [2+3]-Cycloaddition of Thiocarbonyl Ylides with 5-Benzylidene-3-phenylrhodanine

88%

Seyfried M. , Linden A. , Mlostoń G. , Heimgartner H.

2006

tom Vol. 80, nr 8

1363-1376

Reactions of three different thiocarbonyl S-methylides, generated from thiobenzophenone (2), 2,2,4,4-tetramethyl-3-thioxocyclobutanone (3), and adamantanethione (8), respectively, and diazomethane, with 5-benzylidene-3-phenylrhodanine (12) were carried out. The aromatic thiocarbonyl ylide 1a adds chemoselectively to the C,C-double bond, but the spirocyclic 1,3-dithiolane 18, i.e. the [2+3]-cycloadduct with the C=S group of 12,was also formed as a minor product. In the cases of the aliphatic thiocarbonyl ylides 6 and 20, the [2+3]-cycloaddition occurred at the exocyclic C,C-double bond exclusively to give the spirocyclic tetrahydrothiophene derivatives 23 and 21, respectively. Asmooth acid-catalyzed decomposition of 18 yielded the 2-diphenylmethylidene derivative 19. The formation of product 24, which was obtained in the reaction of the sterically congested ylide 6 with 12, is explained by a 1,4-H-shift in an intermediate zwitterionic adduct. The structures of the tetrahydrothiophenes 17, 21 and 23, as well as that of 24, were established by X-ray crystallography.

Reactions of ethyl diazoacetate with thioketones

75%

Kagi M. , Mlostoń G. , Heimgartner H.

1998

tom Vol. 72, nr 4

678-687

The reaction of ethyl diazoacetate (10) with 9H-fluorene-9-thione (2a), thiobenzophenone (2b), and adamantanethione (2c), respectively, in THF yielded 1,3-dithiolane carboxylates (Scheme 2). Whereas in the first two cases the reaction proceeded at room temperature, heating to 60 degree C was necessary when the less reactive 2c was used. The additions with 2a and 2c occured in a regioselective way, yielding 1,3-dithiolane-2-carboxylate 11a and 1,3-dithiolane-4-carboxylate 12c, respectively, with opposite regiochemistry. On the other hand, a mixture of the two regioisomeric cycloadducts 11b and 12b was formed in the case of 2b. The analogous reaction of 10 with the sterically crowded thione 13 gave thiirane 14 as the sole product, and with the corresponding dithione 16, a mixture of the cis- and trans-dithiiranes 17 and 18 was formed (Scheme 3). Desulfurization with tris(dimethylamino)phosphine yielded the alpha, beta -unsaturated esters 15 and 19/20, respectively. The alpha, beta-insaturated ester 22 was the only product in the reaction of 10 with 9H-xanthene-9-thione (21), which had to be carried out at 60 degree C.