A General Approach to Cyathin Diterpenes. Total Synthesis of Allocyathin B<sub>3</sub>

2000-06-17T00:00:00Z (GMT) by Dale E. Ward Yuanzhu Gai Qi Qiao
The synthesis of allocyathin B<sub>3</sub> from an advanced intermediate possessing the ring system and relative stereochemistry but lacking the isopropyl and hydroxymethyl groups is reported. The isopropyl group was introduced by radical cyclization of a methyl propargyl acetal of an α-bromo ketone, and the hydroxymethyl group was generated by Pd-catalyzed carbonylation of a vinyl triflate. The route provides functionalized intermediates that could allow access to more complex members of the cyathin family of diterpenes.