Total Synthesis of Tosyl-Samroiyotmycin A and Its Biological Profiling.

A total synthesis of the enantiopure syn,syn-tosyl-samroiyotmycin A, a C2-symmetric 20-membered antimalarial macrodiolide with syn,syn-configuration of the 8,24-dihydroxy-9,25-dimethyl units and it's enantiopure anti,anti-derivative is described. The synthesis was accomplished utilizing a linear approach in 7 steps and 3 % overall yield via a sequence of diastereoselective methylation of SuperQuat oxazolidinone auxiliary, cross metathesis and Yamaguchi macrolactonization of fully functionalized seco-acids. By a similar approach we gained access to several samroiyotmycin analogues and precursors. Antimalarial activity was tested on multi-resistant (K1) and sensitive (Nf54) P. falciparum strains providing insight into structure activity relationships. Both tosyl-oxazol unit as well as the syn-configuration of the two contiguous stereogenic centers turned out to be beneficial for antiplasmodial activity. For instance, syn,syn-tosyl-samroiyotmycin A showed 3.4 times higher activities than the "tosyl-free" natural product.

Phase-selective low molecular weight organogelators derived from allylated d-mannose.

In the last decades, synthesis and design of low molecular weight organogelators has gained increasing attention due to their versatile use in, for example, cosmetics, biomedicine and oil spill remediation. In this work, three potential gelators have been prepared from allylated d-mannose. Both the gelators and the corresponding gels formed were thoroughly characterized by crystallography, FTIR spectroscopy, SEM, rheometry and NMR spectroscopy, in solution and in solid state. The results showed that two of the compounds phase-selectively form gels with hydrocarbon solvents. The most promising gelator compound is alkene terminated, with the unsaturated end functionality not critical for gel formation, tentatively providing the possibility for customizing the gelation properties by further chemical modification. Alternatively, the alkene group could possibly be utilized as a linker for future coupling to carrier materials or surfaces to further increase the mechanical strength of the gel.