Intramolecular coupling reaction promoted by SmI2 in a synthetic approach of forskolin

Article abstract of DOI:10.1016/0040-4039(94)80114-2

From available hydroxy-aldehyde 6, propargylic derivative 8 was prepared and treated with Bu₃SnH to give in 95% yield the biocyclic vinyl stannone 10. After 10 was converted into the diol 15, this latter was oxidized with the Dess-Martin reagents into the dialdehyde 4. Compound 4 was then submitted to a pinacolic coupling reaction leading to the bicylic cis-diol 3 in a stereospecific manner.