Pyranonaphthoquinone Antibiotics. 3. Synthesis of (+)-9-Deoxygriseusin B and Absolute Configuration Revision of Griseusins A and B

Article abstract of DOI:10.1021/jo00145a023

The synthesis of (+)-9-deoxygriseusin B (3), a close analogue of the natural product, has been achieved.Coupling of the bromonaphthalene derivative 12 with the chiral carbohydrate precursor 11 followed by oxidation gave the allyl ketone 14.Intramolecular ketalization of the bromohydrin intermediate 15 derived from 14 afforded the bromo spiro ketal 16.Treatment of 16 with NaCN and hydrolysis of the cyano group gave the spiro ketal acid 19, which was converted into the final product 3.On the basis of the CD spectrum of 3, which was found to be essentially antipodal to those of griseusins A and B, it was proposed that the original assignment of absolute configuration of the natural products should be revised.