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The cytotoxic, cyclic heptadepsipeptide, natural product callipeltin B was synthesized on a solid-phase support in 15% overall yield. Comparison of the 1H NMR spectra of three synthetic isomers with those of callipeltin B confirmed the configurational reassignment of its threonine residues as d-allothreonine and the assignment of the configuration of its beta-methoxytyrosine residue as (2R,3R).

Hydrogenation Hydrogenation O 0220 Catalytic Olefin Hydrogenation Using N-Heterocyclic Carbene-Phosphine Complexes of Iridium. -Novel complexes having a combination of phosphine and N-heterocyclic carbene ligands are found to be highly reactive towards the homogeneous catalytic hydrogenation of simple olefins, including hindered substrates. -(VAZQUEZ-SERRANO, L. D.; OWENS, B. T.; BURIAK*, J. M.; Chem.