Chem. Pharm. Bull. 54(2) 185—187 (2006)

which showed bluish coloration by spraying modified Ehrlich’s reagent, were isolated along with valiecolin from Emericella purpurea SAMSON & MOUCHACCA IFO 30849 that was isolated from Egyptian desert soil. Recently, new 1,4di-(4-hydroxyphenyl)-2,3-dicyano-1,3-butadiene derivatives, designated epurpurins A to C, were also isolated. Three new compounds with reddish coloration by spraying modified Ehrlich’s reagent, designated emindoles PA (1), PB (2) and PC (3), were isolated from the above fungus. The structure determination of 1, 2 and 3 are reported in this paper. The molecular formulae of 1 and 3 were confirmed as C33H47NO2 by high resolution electron-impact ionization (EI) mass spectrometry. A positive coloration with modified Ehrlich’s reagent (reddish purple) and the fragment ion at m/z 130 [(C9H8N) ] in the EI mass spectra suggested the presence of an indole moiety in 1 and 3. The H-NMR spectra of 1 and 3 (Table 1) were similar to that of emindole DB (4), which had been isolated from E. desertrum SAMSON & MOUCHACCA, except for the appearance of the H-NMR signals assigned as 1,1-dimethyl-2-propenyl residue [d 6.12 (1H, dd), 5.13 (1H, dd), 5.15 (1H, dd), and 1.53 (6H, s) for 1 and 3] and that of the vinylic proton [d 5.53 (br d) for 1 and 3] instead of those of the exo-methylene (d 4.18, 4.51) in 4. The presence of four aromatic protons [d 7.50 (br d), 7.04 (td), 7.10 (td), and 7.26 (br d) in 1 and d 7.50 (br d), 7.04 (br t), 7.11 (ddd), and 7.26 (br d) in 3], the lack of the proton at C-2 in the indole moiety [d 6.89 in 4], and the strong fragment ion of m/z 198 [(C14H16N) ] in EI mass spectra in 1 and 3 showed the presence of an (2-(1,1-dimethyl-2propenyl)indol-3-yl)methyl group. In a preliminary report, we reported the structure of emindole PA (1) as 1 as shown in Chart 1, from the analysis of the H–H and H–C shift correlation (COSY) spectra and the H–C long-range shift correlation (COLOC) spectrum. The H-detected heteronuclear multiple-quantum coherence via direct coupling (HMQC) and heteronuclear multiple bond connectivity by 2D multiple-quantum NMR (HMBC) (Fig. 1) spectra of emindole PA have been carefully analysed. One of two methyl groups observed at d 1.53, which was assigned as the olefinic methyl group in structure 1 in the preliminary report, was not correlated to the olefinic carbon at d 113.9 (C-15), whereas these two methyl protons were correlated with C-2 (d 139.4) of the indole moiety and with C-29 (d 146.5) of the 1,1-dimethyl-2-propenyl residue in the HMBC spectrum. Two methyl groups at d 1.04 and 1.34 were correlated with each of the carbons (d 25.5, 23.3) in the HMBC spectrum, indicating that two methyl groups were connected to one carbon at d 39.8 (C-9). From the above results and further analysis of the HMBC spectrum of 1, the planar structure of emindole PA should consequently be revised as 1 shown in Chart 1. The planar structure of emindole PC (3) was also determined as the same as emindole PA (1), from the detailed analyses of the HMQC and HMBC spectra. The stereochemistry of 1 was determined from the difference H–H nuclear Overhauser enhancement (NOE) spectrum (Fig. 2). When one of the methyl protons at C-9 observed at d 1.04 was irradiated, 4.6 and 5.2% of the NOE of the proton signal at 10-H [d 1.65 (br t)] and one of the methylene protons at C-8 [d 3.06 (dd)], respectively, along with 10.9 and 1.7% of the NOE of 15-H [d 5.53 (br d)] and 4-H [d 7.50 (br d)], respectively, whereas 7.7 and 5.2% of the NOE of 13-H [d 1.90 (br d)] and another proton of the methylene at C-8 [d 2.64 (dd)], respectively, were observed along with February 2006 Chem. Pharm. Bull. 54(2) 185—187 (2006) 185