ALPHA-ALKYLATION AND STEREOCHEMISTRY OF CIS-DECAHYDROQUINOLINES AND TRANS-DECAHYDROQUINOLINES MEDIATED BY THE FORMAMIDINE AND BOC ACTIVATING GROUPS - SYNTHESIS OF PUMILIOTOXIN-C

cis- and trans-decahydroquinolines, as their t-Boc and formamidine derivatives, have been metalated and alkylated. The former gives mainly axial alkylation whereas the latter gives equatorial alkylation in the trans series. For the cis series, the t-Boc derivative gives essentially pure equatorial alkylation as does the formamidine derivative. Several electron-transfer processes occur simultaneously with the ionic alkylation, and this can be altered by use of pentynylcopper or HMPA. Furthermore, cuprates, when employed, gave good yields of alkylation product via radical pathways, but the stereochemistry suffered. A synthesis of the poison dart frog secretion, pumiliotoxin C, has been accomplished using these alkylation techniques.