J. Trojánek

Intramolecular [4+2] cycloaddition of an indolenine☆☆☆

Abstract Attempted transformation of readily accessible 18-methylenevincadifformine (I) to indolenine VI in acidic medium afforded unexpectedly the intramolecular [4+2] cycloadduct VIII in almost quantitative yield

Absolute configuration of (−)-strempeliopine☆

Abstract The (−)-strempeliopine was assigned the absolute configuration depicted in I on the basis of its stereospecific synthesis from (+)-18-methylenevincadifformine (II).

Stereospecific total synthesis of (±)-strempeliopine☆

Abstract The 18-methylene-1,2-dehydroaspidospermidine (III) was stereospecifically transformed into the schizozygane alkaloid strempeliopine (II) in 16,6 % overall yield.

Structure elucidation of roemeridine by X-ray crystallography

Abstract The structure of roemeridine, the major alkaloid from Roemeria hybrida was established by X-ray crystallography. Structure-significant features of the 1H and 13C NMR spectral mass spectral fragmentations are reported.

Synthesis of canthine/erythrinane alkaloid analogs

The pentacyclic lactams9,11, and14 were prepared using a thermal condensation of tryptamine with symmetrical oxodiesters3 and4 as the key step. The formation of the ring E in the tetracyclic compounds5,6,8,10,12, and13 is strongly dependent on the ring size.ZusammenfassungDie pentacyclischen Verbindungen9,11 und14 wurden durch thermische Kondensation von Tryptamin mit symmetrischen Oxodiestern3 und4 als wichtigster Reaktionsstufe dargestellt. Die Bildung des Ringes E in den tetracyclischen Verbindungen5,6,8,10,12 und13 ist stark von der Ringgröße abhängig.