Toward an integrated route to the vernonia allenes and related sesquiterpenoids

• Da Xu,
• Michael A. Drahl and
• Lawrence J. Williams

Beilstein J. Org. Chem. 2011, 7, 937–943, doi:10.3762/bjoc.7.104

• . Fragmentation of a suitable decalin derivative gave the simplified germacrane scaffold. Computational analysis of this and related substrates provides insight into the stereoelectronic requirements of C–C fragmentation. The overall strategy to access these and other sesquiterpenes and the key steps in the

• present sequence are also discussed. Keywords: C–C fragmentation; endocyclic allene; natural product; total synthesis; Introduction Well over 150 allene-containing natural products are known [1][2][3][4][5]. Among these, intriguing complex structures were assigned by Bohlmann and co-workers to isolates

• products, since not all targets in the group of compounds of interest share identical oxidation states or patterns. Recently, we reported the synthesis of 9- and 10-membered cyclopolyenes [28][38], including a new stereospecific allene synthesis via C–C fragmentation. This transformation appears well