Two New Insecticidal Amides and a New Alcoholic Amide from Piper nigrum L inn.

Three new amides, pipgulzarine ( 1 ), pipzorine ( 2 ), and piptahsine ( 3 ), have been isolated from the dried seeds of Piper nigrum L inn. along with nine known constituents: (2 E ,4 E ,8 Z )‐ N ‐(isobutyl)eicosatrienamide, pellitorine, pipercide, piperine, stigmastanol, stigmasterol, decurrenal, stigmasterol 3‐ O ‐ β ‐ D ‐glucopyranoside, and 5,10(15)‐cadinen‐4‐ol. The structures of the new constituents have been established as (2 E ,11 E )‐12‐(benzo[1,3]dioxol‐5‐yl)‐ N ‐(2‐methylpropyl)dodeca‐2,11‐dienamide ( 1 ), (2 E ,12 Z )‐ N ‐(4‐methylpentyl)octadeca‐2,12‐dienamide ( 2 ), and (2 E ,4 S )‐4‐hydroxy‐ N ‐(2‐methylpropyl)hex‐2‐enamide ( 3 ). The structures of 1 – 3 were derived by spectral studies and chemical reactions, and by comparison of spectral data in the case of known constituents. Compounds 1 and 2 , and most of the already known compounds, exhibited toxicity against fourth instar larvae of Aedes aegypti Liston. The isolated (Z ) double bond in 2 was assigned on the basis of its EI‐MS fragmentation pattern and its reaction with OsO 4 . The ( S ) configuration at C(4) of 3 was determined by Horeau 's method. This is the first report of the isolation of a 4‐methylpentylamide from P. nigrum , while shorter branched amides have been reported from this genus [1].