Lewis acid-mediated stereoselective spiroannelation: A facile access to aphidicolane and stemodane B/C/D ring systems

Article abstract of DOI:10.1248/cpb.43.1017

A novel and stereoselective spiroannelation reaction was developed. Treatment of the suitably functionalized cyclohexene derivative (3) with trimethylsilyl trifluoromethanesulfonate (TMSOTf) afforded the spiro[5.5]undecanes 4A and 5S exclusively. Changing the solvent from CH₂Cl₂ to CH₃CN or THF increased the stereoselectivity, predominant formation of 4A in CH₃CN and 5S in THF was observed. The spirocyclic compounds 4A and 5S were transformed into the tricyclo[6.3.1.0^1,6]dodecane derivatives (19A and 27S) corresponding to the B/C/D rings of aphidicolanes (1) and stemodanes (2).

Full text of DOI:10.1248/cpb.43.1017

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