Stereoselective synthesis of (−)-decarestrictine G

The stereochemistry of decarestrictine G was revised to be 5R,6R,9R from theoretical and synthetic studies. The presumable stereoisomer was estimated by comparison of the 1H NMR chemical shifts of the natural product with the calculated values based on density functional theory. With this finding, a synthetic study was performed, and the spectroscopic data for the synthetic (5R,6R,9R)-isomer was fully identical to those of the natural product. The synthesis of (5R,6R,9R)-(−)-decarestrictine G was achieved in 16.5% overall yield in six steps from methyl 3-oxohex-5-enoate via a ring-closing metathesis and a face-selective dihydroxylation of a ten-membered lactone system as the key steps.

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