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Reactions of 9H-Fluorene-9-thione with (Trimethylsilyl)diazomethane

Mlostoń G., Urbaniak K., Linden A., Heimgartner H.

Polish Journal of Chemistry

2007

Vol. 81, nr 11

1849-1860

he [3+2]-cycloaddition of (trimethylsilyl)diazomethane (7) with 9H-fluorene-9-thione (1) at –60°C yields the spirocyclic 2,5-dihydro-5-trimethylsilyl-1,3,4-thiadiazole 10, which eliminates nitrogen at room temperature to give the 1,4-dithiane derivative 13 by dimerization of the intermediate fluorenethione (trimethylsilyl)methanide (11). This thiocarbonyl ylide can be trapped by 1 to give the 2-trimethylsilyl-1,3-dithiolane 14 via [3+2]-cycloaddition. Further more, the 1,3-di pole 11 under goes successfully [3+2]- cycloadditions with the C=S group of the phosphonyldithioformate 15 as well as with the C=C dipolarophiles maleic an hydride (18a) and N-(cyclohexyl)maleimide (18b). The structures of 13 and 14 have been established by X-ray crystallography.

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.