Abetract -Two pungent 2&azepines, chalciporone (1) and norchalciporyl propionate (2), were ieolated from ethyl acetate extracts of fruit-bodies of the fungus Chalcinorue piDeratut3, together with the related but nonpungent 3H-azepinea iaochalciporone (3) and dehydroiaochalciporone (4r.
Fruit-bodies of the nPfefferrahrlingn Chalciporus niperatue (Bull. ex Fr.) Bat. (Baeidiomycetes) are distinguished from other boletee by their peppery taste as well as by lemon-yellow coloured stem bases. We have inveetigated the chemical background for both of these characteristics, and i'; this paper we report on the isolation and structural elucidation of the pungent principles. Pungent tasting extracta were prepared from both frozen and fresh fruit-bodies, and the extracts were subjected to column and preparative thin layer chromatography (tic). Large amounts of the common fungal steroid ergoeterol were excluded from the extracts by Al 0 chromatography, and the major component of the remaininga, chalclporone (l), $ohld be isolated by eilica gel chromatography. 1 ie a very pungent com-1076 0. STEXNER et al.
pound: a few sg applied on the tongue is sufficient to cause an intense burning sensation. In addition, small amounts of norchalciporyl propionate (2), which is approximately as pungent as 1, various amounts of the nonpungent isochalciporone (31, and small amounta of the nonpungent dehydroisochalclporone (4) were isolated. Chalciporone (1) spontaneously isomerlses to ieochalciporone (3), for example during prolonged NMR experiments in CDCl solution at room temperature. Further derivatives were prepared by KBH reduct 4 on of 1 which yielded the alcohol 5, and by hydrogenation of isochalc f porone (3) to form the perhydro derivative 6 (eee Scheme 1). 1078 0. STEXNEX Pt id.
Table 2. 13C NMR data of chalclporone 1 and isochalciporone 3 (100.2 HAz, in CDC13, with THS as internal standard). 1 3 Carbon 6 (ppm) mult. J (Hz) 6 (PPK) mult. J (Hz)