Ruggeri RB,
McClure KF,
Heathcock CH.
* University of California, Berkeley, USA
Daphniphyllum Alkaloids. Part 5. Total Synthesis of (±)-Daphnilactone A: A Novel Fragmentation Reaction.
J. Am. Chem. Soc. 1989;
111: 1530-1531
Key words
(±)-daphnilactone A - aza-Cope rearrangement - Reformatsky reaction - daphniphyllum alkaloids - Swern oxidation - Jones oxidation - hetero-Diels–Alder reaction - Prins cyclization
Significance
In 1989, Heathcock and co-workers reported the first total synthesis of (±)-daphnilactone A through a key fragmentation reaction. The natural product is unique among the daphniphyllium alkaloids, because it features 23 carbons, thereof one not derived from squalene.
Comment
Reformatsky reaction and alkylation of bromoester B yielded C. Hetero-Diels–Alder reaction followed by Prins cyclization rapidly forged aminoether E. The key fragmentation reaction after reduction of E gave rise to single product H. This reaction could proceed either via intermediate F followed by aza-Cope rearrangement to less strained iminium G or by direct C–C cleavage to G.
