Premature birth is a major cause of neonatal mortality and morbidity and is the cause of at least 75 percent of neonatal deaths. Preterm birth causes complications in over 10 percent of pregnancies and places infants at an increased risk for lifelong disabilities such as deafness, blindness, cerebral palsy, learning disability, and development delay. Tocolytic agents have been used to treat premature labor and extend the duration of pregnancy labor by inhibiting labor and reducing contractions of the uterus. Most of the tocolytic agents that have been identified to date have a peptide structure and therefore have the problem of oral bioavailability. Aspargamine-a is an alkaloid that was identified to possess potent anti-oxytocin activity. The total synthesis of this natural product and others with similar structure is hampered because of lack of synthetic methodologies to construct their daunting structures. The development of new methodology necessary to synthesize these compounds will allow us to investigate new class of non-peptide tocolytic agents with advantages over known peptide oxytocin inhibitors. Asparagamine-a, together with several Stemona alkaloids, has a complex structure that includes a cage-type pentacyclic skeleton fused to a methyl tetronate through a double bond (gamma-ylidenetetronate ). Several methodologies to prepare the highly substituted gamma-ylidenetetronate will be investigated based on highly reactive dianion and dianion~equivalent species. A tandem triple ring formation of a disubstituted tropinone will be explored to prepare the pentacyclic cage-type skeleton.
The specific aims for this application are: a) to asses the efficacy of highly reactive dianion species in the construction of the planar bicyclic gamma-ylidene tetronate, b)to access the efficacy of silyl enol ethers in the construction of the planar bicyclic gamma-ylidene tetronate, and c) to investigate a tandem ring closure to synthesize the cage-type azapentacyclic core of the natural products via formation of a substituted tropinone. These studies will lay the foundation for the total synthesis of natural products with potential value as a new class of non-peptide tocolytic agents.
| Barragan, Efrain; Olivo, Horacio F; Romero-Ortega, Moises et al. (2005) Stereoselective addition of the titanium enolate of N-acetyl (4S)-isopropyl-1,3-thiazolidine-2-thione to five-membered N-acyl iminium ions. J Org Chem 70:4214-7 |
| Velazquez, Francisco; Olivo, Horacio F (2002) Synthesis of bicyclic gamma-ylidenetetronates. Org Lett 4:3175-8 |
