The reaction of piperazine with 2-butyne-1,4-ditosylate in a 1:1 ratio yields the cyclic trimer 7 and the cyclic tetramer 8. 1 H NMR investigations on 7 and 8 reveal a dynamic process with ∆G ‡ = 13 kcal/mol. This process is attributed to an inver- Eur.725 sion of the piperazine rings. Single crystals of 7·CH 3 OH, 7·2 CF 3 COOH·H 2 O and 8 have been isolated and investigated by X-ray diffraction. In the first two cases methanol, or water and CF 3 CO 2 − , were included in the interior of the ring. Scheme 1. Reaction of 1 with 2 Scheme 2. Preparation of 7 and 8

The advantages of the palladium-catalyzed allylation described here are the excellent stereoselectivity (spn addition with inversion of the allylic stereocenter for 2-cyclohexenyl substrates and (Z)-unfi addition for acyclic 1,3-disubstituted allylic substrates) and the applicability to a range of allylic substrates" '] readily prepared from allylic alcohols and a,/l-unsaturated aldehydes, as well as the ease with which the reaction can be performed.[3] Prcp;ii-;ition of /rms-and cir-carveols (100 and 98% purity. respectively) will 'Flruhri/rofi Lrrt. 1993, 34. 7619-1622. <~/wu. 1975. 40. 1932-1941 be reported elsewhere. E. Breitrnaier. Strtiiiiire Eliri~jrlrtfon br N M R in Urgiinic Chfniisrr),. Wiley.A rr-allylpalladinm(i1) specie5 such as CIS-8 and cis-9 may also be responsible for the allylation of [*] Prof. [**I This work was supported by the Fonds der Chemischen Industrie. the Deutsche Forschungsgemeinschaft (SFB 247). and the BASF Aktiengesellschaft (Ludwigshafen). J. R. thanks the Studienstiftung des Deutschen Volkes for a Ph.D. grant. We thank Dr. M. Rentzea and Mrs. C. Berndt for FAB' spectrometric measurements. Aiigen Chnir. In/. Ed. EngI. 1995. 34. No. 7 VCH Verlugsgesei/schyfl mbH, 0.69451 Wcrinhein?, 1995 0570-0833/95/0707-078Y 3 iO.OO+ .25/0

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The reaction of piperazine with 2‐butyne‐1,4‐ditosylate in a 1:1 ratio yields the cyclic trimer 7 and the cyclic tetramer 8. 1H NMR investigations on 7 and 8 reveal a dynamic process with ΔG‡ = 13 kcal/mol. This process is attributed to an inversion of the piperazine rings. Single crystals of 7·CH3OH, 7·2 CF3COOH·H2O and 8 have been isolated and investigated by X‐ray diffraction. In the first two cases methanol, or water and CF3CO2−, were included in the interior of the ring.

The addition of two equivalents of hydrochloric acid to N,N′‐diisopropyl‐1,8‐diazacyclotetradeca‐3,5,10,12‐tetrayne (13) afforded a tricyclic scaffold in which a central dichloro‐substituted cyclooctatetraene ring is annelated by two N‐isopropyl‐2,5‐dihydropyrrole rings (14). Three other minor products were congeners of 14 in which one (15, 16) or both (17) of the 2,5‐dihydropyrrole rings are oxidized. In 16 the chlorine atoms adopt different positions.The assignment of the structures of 14–17 is based on the result of an X‐ray investigation on single crystals of 16 and NMR studies. The structural assignments of 14 and 15 were corroborated by labeling experiments with DCl. The regiochemistry in the addition of the second equivalent of hydrochloric acid to 13 was illuminated by DFT calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)