The two indole alkaloids desacetylakuammiliiie (2) and 10-methoxy-desacetylakusmmiline (4) were shown to occure in the upper parts of the small periwinkel Vinca minor L. The structure of the hitherto unknown 10-methoxy-desacetylakuammiline was established on the bases of chemical, spectroscopic and 0.r.d. evidencc.Aus dem in Mitteleuropa heimischen Immergrun -Vinca minor L. (Familie Apocynaceen) -wurden bisher ca. 40 Indolalkaloide isoliert, vgl. [2] [3]. Bezuglich ihrer Ringskelette gehoren diese Basen verschiedenen Typen an (vgl. /4j).In Fortsetzung unserer Arbeit uber die Alkaloide aus I/. minor haben wir die Fraktion aC,o [5] naher untersucht und dabei zwei bisher in dieser Pflanze noch nicht gefundene Alkaloide nachgewiesen. Da eine praparative Trennung der beiden Alkaloide selbst nicht gelang, wurde das Gemisch acetyliert ; die erhaltenen O-Acetylderivate liessen sich nun gut voneinander trennen.
211 Experimental Part. -The mass spcctruni of discretaminc WLS deterrnincd with a CEC 21-110 B m a s spectrometcr (70 CV ionizing encrgy, 180v soiirce tcmperaturc, direct saniplc insertion). 'The authors wish t o thank l>r. J. Schmutz, Ftirschungsinstitut Dr. A . Wander AG, Bern, Switzcrland, for the gencrous gift of thc remainder of his cliscrctaminc satnplc. (18. XI. 74)Summauy. The reduction products voacaiiginol (3) arid coriopharynginol (4), obtaincd from thc indolc alkaloids voacanginc (1) and ctmopharynginc (2) rc!qx:ctivcly, gave, by the trcatmcnt of theit tosylatcs 5 und 6 with tricthylaminct, two fragmrnt:itioti pr'oducts, voaenamine (7) (70-80%) and conoenatnine (8) (2545%) respectively (Schemr. I). The structures of 7 and 8 were derived from spcctroscoyic evidence and some chcrtiical translormations.Conopharynginol tosylatc (6) gave with tcrtiary basc, Ix:sides 8, thc quatcrnary aziridinium salt 12 (58%) (Scheme 3). This salt could undcrgo nuclcopliilic attack, giving compounds of thc A-series with a C-homo-conopharynginc: skelcton (tluc to attack at c(l8) and conqwuntls ot thc B-scries with a spiro-centre (due to attack at cnrlun(5)) (.S'cheme 3). ' LXe structures of theso compounds were elucidatcd using D-incorporation uxperimcnts, 'Hand fiC-NMH. and mass spcctra. On hcating to 230°, acetylated spiroalcohol 22 was ctmvertcd, probably via the ion pair 23, into the basc 16. which on catalytic rcduction gave 13, a mambcr of thc A-series.Thc reactions mentioned above constitute interesting skelctal isomerisations of the conopharyngine skeleton.
Die Indolalkaloide Voacangin(1) und Conopharyngin (2) (vgl. 121) lassen sich leicht mit Lithiumalurniniurnhydrid in Voacanginvl (3) [3J bzw. Conopharynginol (4) und anschliessend in die entsprechendcn Tosylatc 5 bzw. 6 141 uberfilhren. Die kri-153. Mitt, s. [l].
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