The S-(l-beazoyl-Z-bir-methylthfo)vinyl-piperfdfnodithiocarbamates 2a-d are prepand by dithiocarboxylation of phenacyl-pfperfdin~thiocarbawates la-d under phase transfer conditions fellewed by wtbylatloe. In-#IF and sodfun hydride the reaction of la--7+ proceeds by cyclocondensatfon givlng the corresponding subst uted 1,3-dithfole-2-thiones 5a-d after alkylatlon. The crystal structure of the title compound has been determined by X-ray analysis. The molecules exhibit strons deviation from planarity for~thca-oxoketene dlthloacetal molity by a twist of the carbonyl group out of the plane of the ethylene. The plperidfno-dlthlocarbamate fragment is characte ized by close planarlty and a short W-C bond length (1.3270) R).fndicatfng substantial contrlbutfon of twftterfonlc piprrldinlum resonance,fonns to the overall structure. The molecule s ular S . ..C contact distance at 3.090(3) 1 cus a short intramolecand thlocarbonyl group. between its carbonyl Reactions of doubly activated methylene groups with carbon dlsulflde and alkyl halides in the presence of a strong base (e.g. sodium hydride) are known for a long tiara.' Recently we have described the dlthlocarboxylatfon with a-heterocarbanlons of dlthfocarbonate type, but this reactlon proceeds by heterocyclizatlon to 1,3-dlth101e-2-thlones.2 et a1.3 Following the paper of Lawesson concemlng the reaction with CS2 under phase transfer conditions (PTC) we have used the phenacyl-piperldlno-dlthiocarbamates la_d wlth the result that their a-dlthlomcthylene derfvatlves are now easily avallable. In thls paper we are able to report in detail that the obtalned product of the dithiocarboxylation of 1 Is depending on the speclal reaction conditions. So we have found a new convenient synthetic procedure leading to the novel compounds 2. 3 and 3. which may be considered as ethylene derfvatlves with three thlo substftuents. Compounds 2. 1 and 3 were isolated only under PTC whereas In the presence of sodium hydrlde the substltuted 1,3-dithlole-2-thiones 5 were obtalned. Thls fact suggests a possible mcchanisn based on the Influence of the reaction nvadium on the rate of cycllratlon of the pan-enedlthlolate as an intermediate. Our expectations have been found to be In full ag=nt with the experimental results. Yhen cmnd & (R -H) was treated with an excess of carbon disulfide at 20 -25 "C In a two-phase system consisting of chloroform / 10% aqueous potassium hydroxlde solutlon in the presence of an l quimolar amount of trlethylbenzyl armnonfum chloride (TEBA chloride). 3 (R -H) was forncd In 57% yield after alkylation with methyl iodide (
Table 1). 'H-m6 (Cocl)) bfPF4 ?'cd*"' '"? z! H