Enantioselective Total Synthesis of Isoedunol and β-Araneosene Featuring Unconventional Strategy and Methodology

A new synthetic strategy for the enantioselective synthesis of members of the dolabellane family of marine natural products has been demonstrated for the specific examples β-araneosene and isoedunol (1 and 2, respectively) by the pathway outlined in Scheme 1. Key steps include (1) diastereoselective alkylation of Seebach's chiral lactate acetal (6) by the iodide derived from 5; (2) Kulinkovich ethylenation of ester 9 to form the cyclopropanol 10; (3) ring expansion of 10 to form 11; (4) pinacol cyclization of keto aldehyde 12 to form 13a; (5) rearrangement of 13b to 14; (6) propenylation of 14 to 2; and (7) reductive π-transposition to form 1.