Novel Reaction Pathways for 2-Pyridone [4+4] Photoadducts
作者:Peiling Chen、Yanping Chen、Patrick J. Carroll、Scott McN. Sieburth
DOI:10.1021/ol061266z
日期:2006.7.1
Transannular ring closure of a pyridone-furan [4+4] photoadduct has been evaluated in a model system. A combination of nitrogen substitution and an isopropyl group gave full control of the four new stereogenic centers. Chlorination transformed the 1,5-cyclooctadiene to a [4.2.0] ring system instead of to the expected [3.3.0] ring system. Changing an alkene to an enone suppressed this pathway and led to a new rearrangement, converting the 5-8-5 ring system to a 6-7-5 system.
Neuritogenic natural products: The tricyclic diterpene cyrneine A featuring a hexatrienal unit was prepared synthetically for the first time by a Heck reaction, a carbene ring expansion, and a reductive carbonylation. The structure of the natural product was assigned by X‐ray crystal analysis of a synthetic sample.