Studies on inducers of nerve growth factor: synthesis of the cyathin core.

[formula: see text] Compounds that induce the synthesis of nerve growth factor (NGF) are of interest as alternatives to the administration of the native peptide. We have initiated a program to study the NGF synthesis stimulating activity of the erinacine and scabronine diterpenes. Herein, we report an approach to the core cyathin system by sequential application of an oxidative coupling and [4 + 3] cycloaddition.