Synthetic Studies on Echinulin and Related Natural Products. II. : A Total Synthesis of Echinulin

Abstract

Total synthesis of optically active echinulin (14) was achieved. N, N-Bis (3, 3-dimethylallyl) aniline (4) was converted into 2, 4-bis (3, 3-dimethylallyl) aniline (6) in one step (23% yield) by the acid-catalyzed amino-Claisen rearrangement. The aniline (6) was transformed into 2-(1, 1-dimethylallyl)-5, 7-bis (3, 3-dimethylallyl) gramine (11) in 5 steps (15% overall yield). The gramine (11) was condensed with diketopiperazine (12) synthesized from L-alanine, to afford the ester (13). Optically active echinulin (14) was obtained from 13 in two-steps. The overall yield of echinulin (14) from 11 was 21%.