Structure and absolute configuration of a secolignan from Peperomia blanda

Abstract A secolignan, (−)-2-methyl-3-[bis(3′,4′-methylenedioxy-5′-methoxyphenyl) methyl]butyrolactone ( 1 ), with a rare cis configuration was isolated from the aerial parts of Peperomia blanda (Piperaceae). The structure of this compound was elucidated by a combination of spectroscopic methods, including ultraviolet, infrared, 1D- and 2D- nuclear magnetic resonance as well as high resolution mass spectrometry data. The absolute configuration of (−)- 1 was determined as (2 R ,3 S ) by the comparison of experimental electronic circular dichroism (ECD) spectroscopy and time-dependent density functional theory (TDDFT) calculations.