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3 Polish Journal of Chemistry

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Addition of Diazomethane to Phosphonodithioformates and Reactions of Phosphonylated Thiocarbonyl S-Methylides

Urbaniak K., Mlostoń G., Gulea M., Masson S., Heimgartner H.

Polish Journal of Chemistry

2005

Vol. 79 / nr 9

1483-1494

The reaction of phosphonodithioformates 14 with diazomethane at -60 graduate C yielded 2,5-dihydro-1,3,4-thiadiazoles 15 as unstable intermediates. Their structure was evidenced by the base-catalyzed elimination of methylsulfane leading to 1,3,4-thiadiazole- 2-phosphonates. At ca. -35 graduate C, thermal decomposition of 15 by N2-elimination led to reactive thiocarbonyl S-methylides 17. In the absence of trapping reagents, these 1,3-dipoles undergo a head-to-head dimerization leading to 1,4-dithianes 18. An intermediate zwitterionic dimer 19 was detected by 31P NMR spectroscopy. The initially formed thiocarbonyl S-methylide 17 as well as an open-chain zwitterionic dimer 20 was intercepted by methanol. Stable interception products were also obtained with S- and N-nucleophiles.

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

Mlostoń G., Gendek T., Heimgartner H.

Polish Journal of Chemistry

1998

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.

Reactions of ethyl diazoacetate with thioketones

Kagi M., Mlostoń G., Heimgartner H.

Polish Journal of Chemistry

1998

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.