The photochemical behaviour of 5,6-Dehydrokawain (1) was investigated. An aceton solution of 1 was placed into a Petri-dish and allowed to evaporate. After a four weeks irradiation with a 100 W light bulb from a distance of 30 cm  the main component was isolated. Its structure and configuration is elucidated as r-1,c-2-di[6-(4-methoxy-2- pyronyl) ] - t- 3 ,t -4-diphenyIcyclobutane (2) by means of spectroscopic methods and correlation with β-truxinic acid after degradative reaction.
Zeitschrift für Naturforschung B is an international scientific journal which publishes original papers, microreviews, and letters from all areas of inorganic chemistry, solid state chemistry, coordination chemistry, molecular chemistry, and organic chemistry.