Total Synthesis of Decahydroquinoline Poison Frog Alkaloids ent- cis -195A and cis -211A.

The total synthesis of two decahydroquinoline poison frog alkaloids ent- cis - 195A and cis - 211A were achieved in 16 steps (38% overall yield) and 19 steps (31% overall yield), respectively, starting from known compound 1 . Both alkaloids were synthesized from the common key intermediate 11 in a divergent fashion, and the absolute stereochemistry of natural cis - 211A was determined to be 2 R , 4a R , 5 R , 6 S , and 8a S . Interestingly, the absolute configuration of the parent decahydroquinoline nuclei of cis - 211A was the mirror image of that of cis - 195A , although both alkaloids were isolated from the same poison frog species, Oophaga ( Dendrobates ) pumilio , from Panama.