Pergamon 0031-9422(94)00800-0 Phytochemistry, Vol. 38, No. 6, pp. 1437 1439, 1995 Copyright © 1995 Elsevier Science Lid Printed in Great Britain. All rights reserved 0031 9422/95 $9.50 + 0.00 LONGIPINANE DERIVATIVES FROM STEVIA VISCIDA LUISA U. ROMAN, GERARDO MORAN, JUAN D. HERNANDEZ, CARLOS M. CERDA-GARdA-ROJAS* and PEDRO JOSEPH-NATHAN* Instituto de Investigaciones Quimico-Biol6gicas, Universidad Michoacana de San Nicolfis de Hidalgo, Morelia, Mich., 58240 M6xico; *Departamento de Quimica del Centro de Investigaci6n y de Estudios Avanzados, Instituto Polit6cnico Nacional, Apartado 14-740, D.F. 07000, M6xico (Received 31 August 1994) Key Word Index--Stevia viscida; Eupatorieae; Compositae; roots; sesquiterpenes; longipinane. Abstract--Two new longipinane derivatives were isolated from the roots of Stevia viscida. The structures were deduced as longipinan-9ct,15-diangeloyloxy-1-one and longipinan-9~t-angeloyloxy-15-tigloyloxy-1-one on the basis of spectral evidence. INTRODUCTION Studies of nearly 50 Stevia species have shown that longipinene derivatives are frequent in the genus El, 21. In continuation of our search for longipinene derivatives from Stevia 13 61 we studied the chemical constituents of the roots of S. viscida HBK. Chromatography of the hexane extracts yielded the new longipinane derivatives longipinan-9~, 15-diangeloyloxy- 1-one (1) and longipinan-9~-angeloyloxy- 15-tigloyloxy- 1-one (2). Compound 1, isolated as an oil, showed [~']D -- 26° and IR absorptions at 1700 and 1640 cm 1 (unsaturated ester groups). The 1H NMR spectrum (Table 1) showed typical signals for a longipinane skeleton [3, 7] and for two angelate groups [8]. A triplet at 65.07 (J = 3.4 Hz) is assigned to H-9, as in related esters [7], while an AB system at 63.92 and 3.81 (JAB = 11 Hz), owing to a methylene group bearing an ester, is assigned to methyl- ene-15. The or-orientation of this group is evident after comparison of the 1H NMR spectral data of I with those of the C-15 functionalized esters 3 and 4, isolated from S. potrerensis [9] and S. elatior [10],t respectively. The stereochemistry of the methyl group at C-3 and of the angelate group at C-9 follows from the lac NMR chem- ical shifts of C-3 (627. l) and of C- 10 (646.5), respectively (Table 2), which are similar to those of triacetate 5 [7] (C- 3, 626.8; C-10, c~45.0) and different at C-3 for the epimeric triacetate 6 [11] (C-3, 632.4). Compound 2 showed [~]o - 33° and IR absorptions at 1607 and 1650cm -1. Most of the 1H and laCNMR signals were very similar to those of diangelate 1 (Tables 1 and 2). The vinylic signals at 66.85 (1H) and 6.10 (IH) together with the methyl group signals between 62.00 and tThe position of the ester group in 4 was revised. See reference [3]. 1.80 indicate the presence of one tiglate and one angelate ester group in 2. The positional assignment of both esters can be done when the chemical shifts of the signals owing to the protons geminal to the oxygen atoms (H-9, H-15 and H-15') are compared with those of diangelate 1. While the signal for H-9 had a very similar chemical shift in both substances, the signals for H-15 and H-15' experienced an evident change (Table 1). Therefore, the angelate group was located at C-9 and the tiglate group at Table 1. tHNMR spectral data of 1 and 2 (200 MHz, CDCI 3, coupling constants in Hz in parentheses) H l 2 2ct 2.55 dd (8.4, 19.9) 2.55 dd (8.3, 18.4) 2/~ 2.10 dd (6.0, 18.5) 2.12 dd(5.7, 18.5) 3 2.35 m 2.35 m 4 2.18 d(5.5) 2.18 d(5.5) 5 2.00 s 1.98 s 7 1.85 m 1.83 m 7' 1.30 m 1.29 m 9 5.07 t (3.4) 5.08 t (3.1) 11 3.03 d (5.4) 3.07 d (5.5) Me-12 1.09 d (6.7) 1.09 d (6.5} Me-13 0.88 s 0.88 s Me- 14 1.02 s 1.00 s 15 3.92 d (11.0) 3.87 s 15' 3.81 d (11.0) 3.87s OAng (C-9) OAng (C-9) 3 6.10 qq (7.5, 1.5) 6.10 qq (7.5, 1.5) Me-4 2.00 dq (7.5, 1.5) 2.00 dq (7.5, 1.5) Me-5 1.90 quin (1.5) 1.90 quin (1.5) OAng (C-15) OTigl (C-15) 3 6.10 qq (7.5, 1.5) 6.85 qq (7.5, 1.5) Me-4 2.00 dq (7.5, 1.5) 1.81 dq (7.5, 1.5) Me-5 1.90 quin (1.5) 1.83 quin (1.5) 1437