Determination of the Relative and Absolute Configuration of the Dimethylmyristoyl Side Chain of Pneumocandin B<sub>0</sub> by Asymmetric Synthesis
作者:William R. Leonard,、Kevin M. Belyk、Dean R. Bender、David A. Conlon、David L. Hughes、Paul J. Reider
DOI:10.1021/ol0261940
日期:2002.11.1
[reaction: see text] The relative and absoluteconfiguration of the pneumocandin B(0) sidechain has been established as (10R,12S)-dimethylmyristoyl by the stereocontrolled synthesis of both antipodes of the sidechain acid and their comparison to a sample derived from the natural product.
The total synthesis of dysoxylactam A, a novel 17‐membered macrolactam with potent multi‐drug‐resistant reversing activities, has been achieved, starting from 4‐pentene‐1‐al in a longest linear sequence of 17 steps and 9.5% overall yield. The key transformations consist of iterative aldol and ring‐closing metathesis reactions for the construction of the stereochemically enriched polypropionate scaffold
Both enantiomers of callosobruchusic acid were synthesized, confirming its proposed plane structure as (E)-3, 7-dimethyl-2-octene-1, 8-dioic acid. Both of them were biologically active as the copulation release pheromone of Callosobruchus chinensis L.
The absoluteconfiguration of rakicidin C was predicted by comparison of optical rotation data and absoluteconfiguration of APD-cyclic depsipeptides and further determined by total synthesis. The absoluteconfiguration of five chiral centers was determined as 2R, 15R, 16R, 17S, and 19S. Our efficient route involves 19 longest linear steps with an overall yield of 1.49%.
The first totalsynthesis of carmabin A and dragomabin was achieved at 52.3 mg and 43.8 mg scale, respectively. The synthesis led to determination of the configuration of carmabin A and reassignment of the configuration of dragomabin at the stereogenic centre on the alkyne-bearing fragment.