2001 sulfuration, sulfonation, S-alkylation

sulfuration, sulfonation, S-alkylationO 0245

34 - 069Regioselective Thionation of Bicyclic Piperazinediones. — Witha view to prepare enantiomerically pure piperazine derivatives, the lactamcarbonyl groups of derivatives (I) are transformed into thiolactam moieties bytreatment with excess Lawesson reagent. The following LiAlH4 reduction ofpiperazinedithione (IIb) gives the desired target piperazine derivative (VI),whereas the reduction of derivatives (IIa) and (IIIa) by H2/Raney-Ni affordsbicyclic products (IV) and (V) with unaffected 1,3-oxazolidine rings. Inaddition, by use of a reduced amount of Lawesson reagent the sulfuration takesplace regioselectively to give product (IIIa) predominantly. — (SOUKARA,STELLA; WUENSCH, BERNHARD; Tetrahedron 57 (2001) 20, 4359-4363;Inst. Pharm. Chem., Albert-Ludwigs-Univ., D-79104 Freiburg/Br., Germany;EN)

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