(S)-3,7-Dimethyl-5-octene-1,7-diol and Related Oxygenated Monoterpenoids from Petals of Rosa damascena Mill

Article abstract of DOI:10.1021/jf970987x

The methanolic extract obtained from rose flowers was subjected to XAD-2 adsorption chromatography. Prefractionation of the methanolic eluate using multilayer coil countercurrent chromatography (MLCCC) yielded five subfractions. From the least polar subfraction V, a major amount of the key odorants of rose oil, that is, isomeric rose oxides 1a/b, was liberated upon heat treatment at pH 2.5. Further Chromatographic workup of fraction V led, for the first time, to the identification of the genuine rose oxide precursor (S)-3,7-dimethyl-5-octene-1,7-diol (2). In addition to diol 2, the following monoterpene diols have been identified: 3,7-dimethyl-7-octene-1,6-diol (3), 2,6-dimethyl-1,7-octadiene-3,6-diol (4), (2E,5E)-3,7-dimethyl-2,5-octadiene-1,7-diol (5), (2E)-3,7-dimethyl-2,7-octadiene-1,6-diol (6), (2Z,5E)-3,7-dimethyl-2,5-octadiene-1,7-diol (7), (2Z)-3,7-dimethyl-2,7-octadiene-1,6-diol (8), (Z)-2,6-dimethyl-2-octene-1,8-diol (9), (E)-2,6-dimethyl-2-octene-1,8-diol (10), (Z)-2,6-dimethyl-2,7-octadiene-1,6-diol (11), (E)-2,6-dimethyl-2,7-octadiene-1,6-diol (12), (2E,6E)-2,6-dimethyl-2,6-octadiene-1,8-diol (13), (2E,6Z)-2,6-dimethyl-2,6-octadiene-1,8-diol (14), 2,6-dimethyloctane-1,8-diol (15), 2,6-dimethyl-7-octene-1,6-diol (16), (E)-3,7-dimethyl-2-octene-1,8-diol (17), (Z)-3,7-dimethyl-2-octene-1,8-diol (18), 3,7-dimethyloctane-1,7-diol (19), 2,6-dimethyl-7-octene-2,6-diol (20), 3,7-dimethyl-6-octene-1,3-diol (21) and (2E)-3,7-dimethyl-2,6-octadiene-1,4-diol (22).

Full text of DOI:10.1021/jf970987x

1966
J. Agric. Food Chem. 1998, 46, 1966−1970
(S)-3,7-Dim eth yl-5-octen e-1,7-d iol a n d Rela ted Oxygen a ted
Mon oter p en oid s fr om P eta ls of Rosa d a m a scen a Mill.
Holger Knapp,† Markus Straubinger,† Selenia Fornari,† Noriaki Oka,‡ Naoharu Watanabe,‡ and
Peter Winterhalter*,†,§
Institut fu¨r Pharmazie und Lebensmittelchemie, Universita¨t Erlangen-Nu¨rnberg,
Schuhstrasse 19, 91052 Erlangen, Germany, and Department of Applied Biological Chemistry,
Faculty of Agriculture, Shizuoka University, 836 Ohya, Shizuoka 422, J apan
The methanolic extract obtained from rose flowers was subjected to XAD-2 adsorption chromatog-
raphy. Prefractionation of the methanolic eluate using multilayer coil countercurrent chromatog-
raphy (MLCCC) yielded five subfractions. From the least polar subfraction V, a major amount of
the key odorants of rose oil, that is, isomeric rose oxides 1a /b, was liberated upon heat treatment
at pH 2.5. Further chromatographic workup of fraction V led, for the first time, to the identification
of the genuine rose oxide precursor (S)-3,7-dimethyl-5-octene-1,7-diol (2). In addition to diol 2, the
following monoterpene diols have been identified: 3,7-dimethyl-7-octene-1,6-diol (3), 2,6-dimethyl-
1,7-octadiene-3,6-diol (4), (2E,5E)-3,7-dimethyl-2,5-octadiene-1,7-diol (5), (2E)-3,7-dimethyl-2,7-
octadiene-1,6-diol (6), (2Z,5E)-3,7-dimethyl-2,5-octadiene-1,7-diol (7), (2Z)-3,7-dimethyl-2,7-octadiene-
1,6-diol (8), (Z)-2,6-dimethyl-2-octene-1,8-diol (9), (E)-2,6-dimethyl-2-octene-1,8-diol (10), (Z)-2,6-
dimethyl-2,7-octadiene-1,6-diol (11), (E)-2,6-dimethyl-2,7-octadiene-1,6-diol (12), (2E,6E)-2,6-dimethyl-
2,6-octadiene-1,8-diol (13), (2E,6Z)-2,6-dimethyl-2,6-octadiene-1,8-diol (14), 2,6-dimethyloctane-1,8-
diol (15), 2,6-dimethyl-7-octene-1,6-diol (16), (E)-3,7-dimethyl-2-octene-1,8-diol (17), (Z)-3,7-dimethyl-
2-octene-1,8-diol (18), 3,7-dimethyloctane-1,7-diol (19), 2,6-dimethyl-7-octene-2,6-diol (20), 3,7-
dimethyl-6-octene-1,3-diol (21) and (2E)-3,7-dimethyl-2,6-octadiene-1,4-diol (22).
Keyw or d s: (S)-3,7-Dimethyl-5-octene-1,7-diol; monoterpene diols; rose oxides; aroma precursors;
multilayer coil countercurrent chromatography; rose petals; Rosa damascena Mill.
INTRODUCTION
EXPERIMENTAL PROCEDURES
P la n t Ma ter ia l. Rose flowers (Rosa damascena Mill.) were
harvested at their full bloom stage in the Shizuoka prefecture,
J apan.
The C13-norisoprenoid ketone, â-damascenone, and
the isomeric monoterpene ethers, rose oxides 1a /b, are
major aroma contributors of Bulgarian rose oil (Ohloff
and Demole, 1987, and references cited therein). Recent
results of Surburg et al. (1993) have indicated the
presence of labile precursors for both of the above-
mentioned key aroma compounds in rose petals. By
using a gentle isolation technique, that is, vacuum
headspace concentration, the authors reported that
neither â-damascenone nor the isomeric rose oxides 1a /b
could be detected in the aroma isolate of rose flowers.
Consequently, both aroma compounds appear to be
rearrangement products that are formed during the
steam distillation process from extremely labile progeni-
tors. Whereas in a most recent study (Straubinger et
al., 1997a) an immediate precursor of â-damascenone
has been isolated from rose flowers, the formation of
isomeric rose oxides 1a /b remained obscure.
Extr a ction of Rose F low er s a n d P r ep a r a tion of a n
XAD-2 Extr a ct. Rose flowers (10 kg) were homogenized in
ice-cooled 80% aqueous MeOH. After filtration, the organic
solvent was concentrated in vacuo. Freeze-drying of the
aqueous residue yielded 206 g of a crude extract. This extract
was subjected to XAD-2 column chromatography (700 × 55
mm i.d., 1 kg XAD) in portions of 26 g (Gu¨nata et al., 1985).
The column was rinsed with water. Subsequent elution of the
retained material with MeOH and concentration under re-
duced pressure yielded ≈40 g of an aroma precursor concen-
trate.
Mu ltilayer Coil Cou n ter cu r r en t Ch r om atogr aph y (ML-
CCC) Sep a r a tion . For the initial fractionation of the residue,
MLCCC (Ito, 1986) was used (multilayer coil separator-
extractor, P. C. Inc., Potomac, MD; equipped with an 85 m ×
2.6 mm i.d. PTFE tubing; solvent system of CHCl3/MeOH/H2O
7:13:8; injection volume of 2.5 g of extract dissolved in 5 mL
of aqueous phase). To facilitate the screening of aroma
precursors, sequential MLCCC fractions were pooled into five
groups, that is, combined MLCCC fractions I-V.
Isola tion of P olyols 2, 12, 13, a n d 21. A screening of
fractions I-V for rose oxide generating progenitors was carried
out by acid hydrolysis (SDE, pH 2.5, 1 h). The generated
compounds from these hydrolyses were then determined by
GC/MS. The diethyl ether extract of fraction V was further
separated by MLCCC (n-BuOH/MeOH/H2O 10:1:10), and the
major compounds were finally purified by flash chromatogra-
phy and normal phase HPLC using hexane/MTBE gradients
(Straubinger et al., 1997b).
In this paper, we report the isolation and structural
elucidation of the labile monoterpene diol 2, which was
found to be the major genuine precursor for isomeric
rose oxides 1a /b in rose flowers.
* Author to whom correspondence should be addressed (e-
mail P.Winterhalter@tu-bs.de; fax ++49-531-391-7230).
† Universita¨t Erlangen-Nu¨rnberg.
‡ Shizuoka University.
§ Present address: TU Braunschweig, Schleinitzstrasse 20,
38106 Braunschweig, Germany.
S0021-8561(97)00987-4 CCC: $15.00 © 1998 American Chemical Society
Published on Web 04/09/1998

Oxygenated Terpenoids from Rose Petals
J. Agric. Food Chem., Vol. 46, No. 5, 1998 1967
Sp ectr a l Da ta for Isola ted Mon oter p en e Diols 2, 12,
13, a n d 21. 2: 1H NMR (360 MHz, CDCl3) δ 0.89 (3H, d, J )
6.5 Hz, Me-C3), 1.30 (6H, s, 2Me-C7), 1.35 (1H, m, H2a), 1.59
(1H, m, H2b), 1.67 (1H, m, H3), 1.91 (1H, m, H4a), 2.01 (1H,
m, H4b), 3.60 (1H, ddd, J ) 12.0, 7.0, 2.0 Hz, H1a), 3.67 (1H,
ddd, J ) 12.0, 7.0, 3.0 Hz, H1b), 5.56 (1H, ddd, J ) 15.0, 5.5,
1.0 Hz, H5), 5.61 (1H, d, J ) 15.0 Hz, H6); 13C NMR (91 MHz,
CDCl3) δ 19.5 (Me-C3), 29.6 (2Me-C7), 29.7 (C3), 38.9 (C2),
39.5 (C4), 60.5 (C1), 70.5 (C7), 125.1 (C5), 139.4 (C6).
12: 1H NMR (250 MHz, CDCl3) δ 1.30 (3H, s, Me-C6), 1.59
(2H, m, H25), 1.65 (3H, d, J ) 1.0 Hz, Me-C2), 2.08 (2H, m,
H24), 3.98 (2H, s, H21), 5.07 (1H, dd, J ) 11.0, 1.5 Hz, H8a),
5.22 (1H, dd, J ) 17.5, 1.5 Hz, H8b), 5.41 (1H, tq, J ) 7.0, 1.0
Hz, H3), 5.91 (1H, dd, J ) 17.5, 11.0 Hz, H7); 13C NMR (63
MHz, CDCl3) δ 13.6 (Me-C2), 22.3 (C4), 27.8 (Me-C6), 41.7 (C5),
68.7 (C1), 73.3 (C6), 111.8 (C8), 125.8 (C3), 135.9 (C2), 144.8
(C7).
λmax 203, 225, 271 nm; IR (NaCl) ν (cm-1) 3375 (OH), 3087,
2973, 2949, 1651, 1449, 1412, 1372, 1151, 1115, 1058, 997, 920
(-CHdCH2), 900 (>CdCH2); 1H NMR (250 MHz, CDCl3) δ
1.28 (3H, s, Me-C6), 1.61 (4H, m, H24, H25), 1.71 (3H, d, J )
1.0 Hz, Me-C2), 4.03 (1H, tdd, J ) 5.0, 1.0, 1.0 Hz, H3), 4.82
(1H, dd, J ) 1.5, 1.0, Hz, H1a), 4.94 (1H, ddq, J ) 1.5, 1.0, 1.0
Hz, H1b), 5.04 (1H, dd, J ) 11.0, 1.5 Hz, H8a), 5.21 (1H, dd, J
) 18.0, 1.5 Hz, H8b), 5.88 (1H, dd, J ) 18.0, 11.0 Hz, H7); 13
C
NMR (63 MHz, CDCl3) δ 17.7/17.8 (Me-C2), 27.8/28.2 (Me-C6),
29.1/29.3 (C4), 37.6/38.2 (C5), 72.9 (C6), 75.5/76.0 (C3), 110.8
(C1), 111.7/111.9 (C8), 144.8/145.0 (C7), 147.3/147.5 (C2).
(2E,5E)-3,7-Dimethyl-2,5-octadiene-1,7-diol (5) and (6RS)-
(E)-3,7-Dimethyl-2,7-octadiene-1,6-diol (6) from Geraniol. 5:
Ri (DB-Wax) 2345; Ri (DB-5) 1388; UV (MeOH) λmax 204, 237
nm; IR (NaCl) ν (cm-1) 3357 (OH), 2973, 2928, 1665 (CdC),
1440, 1378, 1233, 1150, 1094, 1045, 974 (CdC trans), 846
1
(>CdCH-); H NMR (360 MHz, CDCl3) δ 1.31 (6H, s, 2Me-
13: Ri (DB-Wax) 2635; Ri (DB-5) 1522; UV (MeOH) λmax 209
nm; IR (NaCl) ν (cm-1) 3336 (OH), 2965, 2919, 2861, 1669
(CdC), 1442, 1384, 1236, 1065, 1007, 843 (>CdCH-); 1H NMR
(250 MHz, CDCl3) δ 1.64 (3H, d, J ) 1.0 Hz, Me-C2), 1.66 (3H,
d, J ) 1.0 Hz, Me-C6), 2.02-2.23 (4H, m, H24, H25), 2.88 (2H,
br s, OH), 3.95 (2H, s, H21), 4.11 (2H, d, J ) 7.0 Hz, H28), 5.37
(1H, tq, J ) 7.0, 1.0 Hz, H3), 5.38 (1H, tq, J ) 7.0, 1.0 Hz,
H7); 13C NMR (63 MHz, CDCl3) δ 13.6 (Me-C2), 16.0 (Me-C6),
25.4 (C4), 38.9 (C5), 58.9 (C8), 68.3 (C1), 123.8 (C7), 125.0 (C3),
134.9 (C2), 138.3 (C6).
C7), 1.65 (3H, d, J ) 1.0 Hz, Me-C3), 2.71 (2H, d, J ) 6.0 Hz,
H24), 4.14 (2H, d, J ) 7.0 Hz, H21), 5.41 (1H, tq, J ) 7.0, 1.0
Hz, H2), 5.58 (1H, dt, J ) 16.0, 6.0 Hz, H5), 5.65 (1H, d, J )
16.0 Hz, H6); 13C NMR (63 MHz, CDCl3) δ 16.3 (Me-C3), 29.6
(2Me-C7), 42.0 (C4), 59.1 (C1), 70.6 (C7), 124.2 (C2), 124.2 (C5),
137.4 (C3), 139.9 (C6). 6: Ri (DB-Wax) 2472; Ri (DB-5) 1437;
UV (MeOH) λmax 208 nm; IR (NaCl) ν (cm-1) 3341 (OH), 3074,
2971, 2941, 1668 and 1651 (CdC), 1444, 1381, 1308, 1239,
1181, 1100, 1062, 1002, 899 (>CdCH2), 756; 1H NMR (360
MHz, CDCl3) δ 1.58 (2H, m, H25), 1.59 (3H, d, J ) 1.0 Hz,
Me-C3), 1.65 (3H, d, J ) 1.0 Hz, Me-C7), 1.98 (2H, m, H24),
3.95 (1H, td, J ) 6.5, 1.0 Hz, H6), 4.04 (2H, d, J ) 7.0 Hz,
H21), 4.76 (1H, dd, J ) 1.5, 1.0 Hz, H8a), 4.86 (1H, dq, J )
1.5, 1.0 Hz, H8b), 5.34 (1H, tq, J ) 7.0, 1.0 Hz, H2); 13C NMR
(63 MHz, CDCl3) δ 16.0 (Me-C3), 17.4 (Me-C7), 32.6 (C5), 35.3
(C4), 58.8 (C1), 75.0 (C6), 110.8 (C8), 123.6 (C2), 138.5 (C3),
147.2 (C7).
(2Z,5E)-3,7-Dimethyl-2,5-octadiene-1,7-diol (7) and (6RS)-
(Z)-3,7-Dimethyl-2,7-octadiene-1,6-diol (8) from Nerol. 7: Ri
(DB-Wax) 2287; Ri (DB-5) 1355; UV (MeOH) λmax 207, 236 nm;
IR (NaCl) ν (cm-1) 3357 (OH), 2971, 2929, 1665 (CdC), 1441,
1376, 1234, 1151, 1090, 1050, 972 (CdC trans), 895; 1H NMR
(250 MHz, CDCl3) δ 1.31 (6H, s, 2Me-C7), 1.73 (3H, dt, J )
1.0, 1.0 Hz, Me-C3), 2.79 (2H, d, J ) 6.0 Hz, H24), 4.14 (2H,
dd, J ) 7.0, 1.0 Hz, H21), 5.49 (1H, tq, J ) 7.0, 1.0 Hz, H2),
5.55 (1H, dt, J ) 15.0, 6.0 Hz, H5), 5.66 (1H, d, J ) 15.0 Hz,
H6); 13C NMR (63 MHz, CDCl3) δ 23.5 (Me-C3), 29.8 (2Me-
C7), 34.8 (C4), 59.1 (C1), 70.6 (C7), 124.2 (C2/6), 124.9 (C2/6),
138.3 (C3), 139.3 (C5). 8: Ri (DB-Wax) 2423; Ri (DB-5) 1415;
UV (MeOH) λmax 203 nm; IR (NaCl) ν (cm-1) 3349 (OH), 2969,
2937, 2872, 1652 (CdC), 1445, 1377, 1322, 1150, 1100, 1053,
997, 900 (>CdCH2), 837 (>CdCH-); 1H NMR (360 MHz,
CDCl3) δ 1.58 (1H, dddd, J ) 12.5, 9.0, 8.0, 5.0 Hz, H5a), 1.66
(1H, dddd, J ) 12.5, 8.5, 8.0, 4.0 Hz, H5b), 1.69 (3H, s, Me-
C7), 1.70 (3H, d, J ) 1.0 Hz, Me-C3), 2.02 (1H, ddd, J ) 13.5,
8.0, 5.0 Hz, H4a), 2.34 (1H, ddd, J ) 13.5, 8.5, 8.0 Hz, H4b),
3.94 (1H, ddd, J ) 9.0, 4.0, 1.0 Hz, H6), 3.98 (1H, dd, J )
12.5, 7.0 Hz, H1a), 4.14 (1H, dd, J ) 12.5, 7.0 Hz, H1b), 4.79
(1H, dd, J ) 1.5, 1.0 Hz, H8a), 4.91 (1H, d, J ) 1.5 Hz, H8b),
5.49 (1H, ddq, J ) 7.0, 7.0, 1.0 Hz, H2); 13C NMR (63 MHz,
CDCl3) δ 17.9 (Me-C7), 22.9 (Me-C3), 27.4 (C4), 32.7 (C5), 58.1
(C1), 73.9 (C6), 110.5 (C8), 124.6 (C2), 140.0 (C3), 147.5 (C7).
(ii) Preparation of (3RS)-(Z)-2,6-Dimethyl-2-octene-1,8-diol
(9) from Isopulegol (Waddell and Ross, 1987): Ri (DB-Wax)
2382; Ri (DB-5) 1482; UV (MeOH) λmax 202 nm; IR (NaCl) ν
(cm-1) 3333 (OH), 2951, 2924, 1455, 1052, 846 (>CdCH-); 1H
NMR (360 MHz, CDCl3) δ 0.85 (3H, d, J ) 6.5 Hz, Me-C6),
1.25-1.70 (5H, m, H25, H6, H27), 1.74 (3H, d, J ) 1.0 Hz, Me-
C2), 2.09 (2H, m, H24), 3.43 (1H, ddd, J ) 10.0, 6.5, 3.0 Hz,
H8a), 3.48 (1H, ddd, J ) 10.0, 6.0, 3.5 Hz, H8b), 4.10 (2H, d, J
) 1.0 Hz, H21), 5.21 (1H, ttq, J ) 7.0, 1.0, 1.0 Hz, H3); 13C
NMR (91 MHz, CDCl3) δ 19.6 (Me-C6), 21.2 (Me-C2), 24.8 (C4),
28.3 (C6), 37.0 (C5), 38.9 (C7), 60.4 (C8), 60.9 (C1), 128.3 (C3),
134.2 (C2).
21: 1H NMR (360 MHz, CDCl3) δ 1.26 (3H, s, Me-C3), 1.56
(2H, m, H24), 1.63 (3H, d, J ) 1.0 Hz, Me-C7), 1.67 (1H, ddd,
J ) 14.5, 6.5, 4.5 Hz, H2a), 1.69 (3H, d, J ) 1.0 Hz, Me-C7),
1.81 (1H, ddd, J ) 14.5, 7.5, 4.5 Hz, H2b), 2.06 (2H, m, H25),
3.86 (1H, ddd, J ) 11.0, 6.5, 4.5 Hz, H1a), 3.92 (1H, ddd, J )
11.0, 7.5, 4.5 Hz, H1b), 5.15 (1H, tqq, J ) 7.0, 1.0, 1.0 Hz, H6);
13C NMR (91 MHz, CDCl3) δ 17.7 (Me-C7), 22.7 (C5), 25.7 (Me-
C7), 26.7 (Me-C3), 41.7 (C2), 42.4 (C4), 59.9 (C1), 74.0 (C3),
124.1 (C6), 132.1 (C7).
GC/MS Id en tifica tion of Min or Con stitu en ts. The diols
3-11 and 14-20 were identified by GC/MS analyses through
comparison with authentic reference compounds (Winterhalter
et al., 1998). Compounds 2-12 and 14-21 were prepared
according to published procedures. Diol 22 was donated, and
diol 13 was commercially obtained (Aldrich, Steinheim, Ger-
many).
P r ep a r a tion of Refer en ce Com p ou n d s. (i) Photooxida-
tion (Tietze and Eicher, 1981). A solution of 0.5 g of the
monoterpene alcohol and 70 mg of Rose Bengal in MeOH (25
mL) was irradiated with an UV lamp at 25 °C in an oxygen
atmosphere (10 h). Na2SO3 reduction (25 °C, 1 h), filtration,
evaporation of the solvent in vacuo and flash chromatographic
purification yielded the diols 2-8.
(3S)-(E)-3,7-Dimethyl-5-octene-1,7-diol (2) and (3S,6RS)-3,7-
Dimethyl-7-octene-1,6-diol (3) from (S)-(-)-Citronellol. 2: Ri
(DB-Wax) 2220; Ri (DB-5) 1346; UV (MeOH) λmax 203 nm; IR
(NaCl) ν (cm-1) 3358 (OH), 2969, 2927, 1459, 1377, 1232, 1152,
1058, 972 (CdC, trans); 1H NMR (360 MHz, CDCl3) δ 0.89 (3H,
d, J ) 6.5 Hz, Me-C3), 1.30 (6H, s, 2Me-C7), 1.35 (1H, m, H2a),
1.59 (1H, m, H2b), 1.67 (1H, m, H3), 1.91 (1H, m, H4a), 2.01
(1H, m, H4b), 2.60 (1H, br s, OH), 2.87 (1H, br s, OH), 3.60
(1H, ddd, J ) 12.0, 7.0, 2.0 Hz, H1a), 3.67 (1H, ddd, J ) 12.0,
7.0, 3.0 Hz, H1b), 5.56 (1H, ddd, J ) 15.0, 5.5, 1.0 Hz, H5),
5.61 (1H, d, J ) 15.0 Hz, H6); 13C NMR (91 MHz, CDCl3) δ
19.5 (Me-C3), 29.6 (2Me-C7), 29.7 (C3), 38.9 (C2), 39.5 (C4),
60.5 (C1), 70.5 (C7), 125.1 (C5), 139.4 (C6). 3: Ri (DB-Wax)
2369; Ri (DB-5) 1414; UV (MeOH) λmax 203 nm; IR (NaCl) ν
(cm-1) 3355 (OH), 2934, 2871, 1650 (CdC), 1451, 1377, 1108,
1059, 898 (>CdCH2); 1H NMR (360 MHz, CDCl3) δ 0.91 (3H,
d, J ) 6.0 Hz, Me-C3), 1.24-1.63 (7H, m, H22, H3, H24, H25),
1.72 (3H, s, Me-C7), 3.64 (1H, ddd, J ) 11.0, 7.5, 2.5 Hz, H1a),
3.71 (1H, ddd, J ) 11.0, 7.0, 2.5 Hz, H1b), 4.03 (1H, t, J ) 6.5
Hz, H6), 4.82 (1H, d, J ) 1.0 Hz, H8a), 4.92 (1H, d, J ) 1.0
Hz, H8b); 13C NMR (63 MHz, CDCl3) δ 17.4/17.5 (Me-C7), 19.6
(Me-C3), 29.3/29.5 (C3), 32.2 (C5), 32.6/32.7 (C4), 39.8 (C2),
61.0 (C1), 76.0/76.3 (C6), 110.9/111.1 (C8), 147.5/147.6 (C7).
(3RS,6RS)-2,6-Dimethyl-1,7-octadiene-3,6-diol (4) from
(()-Linalool: Ri (DB-Wax) 2135; Ri (DB-5) 1277; UV (MeOH)
(iii) ω-Hydroxylation. Synthesis of diols 10-12 and 14 was
accomplished by SeO2 oxidation of the monoterpene alcohols,
followed by LiAlH4 reduction of the resulting aldehyde and
liquid chromatographic purification (Behr et al., 1978).

1968 J. Agric. Food Chem., Vol. 46, No. 5, 1998
Knapp et al.
(6RS)-(E)-2,6-Dimethyl-2-octene-1,8-diol
(10)
from
665; 1H NMR (360 MHz, CDCl3) δ 0.85 (3H, d, J ) 6.5 Hz,
Me-C7), 1.26-1.58 (5H, m, H25, H26, H7), 1.60 (3H, s, Me-
C3), 1.92-2.10 (2H, m, H24), 3.36 (1H, dd, J ) 10.5, 6.5 Hz,
H8a), 3.43 (1H, dd, J ) 10.5, 6.5 Hz, H8b), 4.08 (2H, d, J ) 7.0
Hz, H21), 5.35 (1H, t, J ) 7.0 Hz, H2); 13C NMR (63 MHz,
CDCl3) δ 16.1 (Me-C3), 16.5 (Me-C7), 24.9 (C5), 32.6 (C6), 35.6
(C7), 39.7 (C4), 59.4 (C1), 68.3 (C8), 123.4 (C2), 139.9 (C3).
(()-Citronellol: Ri (DB-Wax) 2550; Ri (DB-5) 1496; UV (MeOH)
λmax 203 nm; IR (NaCl) ν (cm-1) 3408 (OH), 2959, 2924, 1644
(CdC), 1455, 1377, 1057, 1011, 835 (>CdCH-); 1H NMR (250
MHz, CDCl3) δ 0.92 (3H, d, J ) 6.5 Hz, Me-C6), 1.18-1.70
(5H, m, H25, H6, H27), 1.67 (3H, br s, Me-C2), 2.06 (2H, m,
H24), 3.68 (1H, ddd, J ) 10.5, 6.5, 3.0 Hz, H8a), 3.69 (1H, ddd,
J ) 10.5, 6.0, 3.5 Hz, H8b), 4.00 (2H, s, H21), 5.40 (1H, tq, J )
7.0, 1.0 Hz, H3); 13C NMR (63 MHz, CDCl3) δ 13.6 (Me-C2),
19.5 (Me-C6), 25.0 (C4), 29.1 (C6), 36.7 (C5), 39.8 (C7), 61.1
(C8), 69.0 (C1), 126.4 (C3), 134.6 (C2).
(7RS)-(2Z)-3,7-Dimethyl-2-octene-1,8-diol (18) from (2E,6Z)-
2,6-Dimethyl-8-hydroxyocta-2,6-dienal: Ri (DB-Wax) 2515; Ri
(DB-5) 1492; UV (MeOH) λmax 203 nm; IR (NaCl) ν (cm-1) 3347
(OH), 2952, 2929, 2872, 1668 (CdC), 1462, 1379, 1216, 1030,
1
(6RS)-(Z)-2,6-Dimethyl-2,7-octadiene-1,6-diol (11) and (6RS)-
(E)-2,6-Dimethyl-2,7-octadiene-1,6-diol (12) from (()-Linalyl
Acetate. 11: Ri (DB-Wax) 2254; Ri (DB-5) 1346; UV (MeOH)
757, 665; H NMR (360 MHz, CDCl3) δ 0.84 (3H, d, J ) 6.5
Hz, Me-C7), 1.26-1.58 (5H, m, H25, H26, H7), 1.67 (3H, d, J
) 1.0 Hz, Me-C3), 1.92-2.10 (2H, m, H24), 3.36 (1H, dd, J )
10.5, 6.5 Hz, H8a), 3.43 (1H, dd, J ) 10.5, 6.5 Hz, H8b), 4.08
λ
max 205 nm; IR (NaCl) ν (cm-1) 3357, 3087, 2969, 2925, 1718,
1160, 999 and 918 (-CHdCH2), 816 (>CdCH-); 1H NMR (360
MHz, CDCl3) δ 1.29 (3H, s, Me-C6), 1.59 (2H, m, H25), 1.79
(3H, d, J ) 1.0 Hz, Me-C2), 2.12 (2H, m, H24), 4.12 (2H, d, J
) 1.0 Hz, H21), 5.07 (1H, dd, J ) 11.0, 1.5 Hz, H8a), 5.22 (1H,
dd, J ) 17.0, 1.5 Hz, H8b), 5.31 (1H, ttq, J ) 7.5, 1.0, 1.0 Hz,
H3), 5.91 (1H, dd, J ) 17.0, 11.0 Hz, H7); 13C NMR (91 MHz,
CDCl3) δ 21.4 (Me-C2), 22.4 (C4), 28.1 (Me-C6), 42.1 (C5), 61.6
(C1), 73.5 (C6), 111.9 (C8), 128.5 (C3), 134.6 (C2), 144.9 (C7).
12: Ri (DB-Wax) 2324; Ri (DB-5) 1362; UV (MeOH) λmax 203,
222 nm; IR (NaCl) ν (cm-1) 3357 (OH), 3087, 2972, 2925, 1641
(CdC), 1454, 1412, 1371, 1159, 1114, 1079, 1065, 1001 and
921 (-CHdCH2), 851, 808 (>CdCH-); 1H NMR (360 MHz,
CDCl3) δ 1.30 (3H, s, Me-C6), 1.59 (2H, m, H25), 1.65 (3H, d,
J ) 1.0 Hz, Me-C2), 2.08 (2H, m, H24), 3.98 (2H, s, H21), 5.07
(1H, dd, J ) 11.0, 1.5 Hz, H8a), 5.22 (1H, dd, J ) 17.5, 1.5 Hz,
H8b), 5.41 (1H, tq, J ) 7.0, 1.0 Hz, H3), 5.91 (1H, dd, J ) 17.5,
11.0 Hz, H7); 13C NMR (63 MHz, CDCl3) δ 13.6 (Me-C2), 22.3
(C4), 27.8 (Me-C6), 41.7 (C5), 68.7 (C1), 73.3 (C6), 111.8 (C8),
125.8 (C3), 135.0 (C2), 144.8 (C7).
(2H, d, J ) 7.0 Hz, H21), 5.35 (1H, tq, J ) 7.0, 1.0 Hz, H2); 13
C
NMR (63 MHz, CDCl3) δ 16.5 (Me-C7), 23.4 (Me-C3), 25.2 (C5),
31.8 (C4), 32.6 (C6), 35.4 (C7), 59.0 (C1), 68.3 (C8), 124.3 (C2),
140.1 (C3).
(v) Diols 19-21 Prepared by Epoxidation (MCPB) and
Subsequent LiAlH4 Reduction according to the Method of
Williams et al. (1980). (3RS)-3,7-Dimethyloctane-1,7-diol (19)
from (()-Citronellol: Ri (DB-Wax) 2215; Ri (DB-5) 1364; UV
(MeOH) λmax 204 nm; IR (NaCl) ν (cm-1) 3357 (OH), 2965, 2935
(C-H), 1644, 1464, 1379, 1218, 1157, 1058, 937, 910, 759; 1H
NMR (250 MHz, CDCl3) δ 0.89 (3H, d, J ) 6.5 Hz, Me-C3),
1.20 (6H, s, 2 Me-C7), 1.25-1.68 (9H, m, H22, H3, H24, H25,
H26), 3.62 (1H, ddd, J ) 11.0, 7.0, 6.5 Hz, H1a), 3.68 (1H, ddd,
J ) 11.0, 7.5, 6.0 Hz, H1b); 13C NMR (63 MHz, CDCl3) δ 19.5
(Me-C3), 21.4 (C5), 28.9 (C3), 29.1 (Me-C7), 29.2 (Me-C7), 37.4
(C4), 39.5 (C2), 43.8 (C6), 60.5 (C1), 70.9 (C7).
(6RS)-2,6-Dimethyl-7-octene-2,6-diol (20) from (()-Linalyl
Acetate: Ri (DB-Wax) 1988; Ri (DB-5) 1233; UV (MeOH) λmax
208 nm; IR (NaCl) ν (cm-1) 3399 (OH), 3087, 2969, 2911, 1643
(2E,6Z)-2,6-Dimethyl-2,6-octadiene-1,8-diol (14) from Nerol:
Ri (DB-Wax) 2597; Ri (DB-5) 1503; UV (MeOH) λmax 203 nm;
IR (NaCl) ν (cm-1) 3904 (OH), 2965, 2918, 1668, 1445, 1377,
1053 (C-O prim.), 1006, 839 (>CdCH-); 1H NMR (360 MHz,
CDCl3) δ 1.64 (3H, d, J ) 1.0 Hz, Me-C2), 1.75 (3H, d, J ) 1.0
Hz, Me-C6), 2.15 (4H, m, H24, H25), 3.97 (2H, s, H21), 4.06
(2H, d, J ) 7.5 Hz, H28), 5.40 (1H, m, H3), 5.42 (1H, tq, J )
7.5, 1.0 Hz, H7); 13C NMR (63 MHz, CDCl3) δ 13.7 (Me-C2),
23.2 (Me-C6), 25.2 (C4), 31.3 (C5), 58.8 (C8), 68.4 (C1), 124.8
(C2), 124.9 (C6), 135.6 (C7), 138.3 (C3).
(iv) Preparation of Diols 15-18 Using Baker’s Yeast Reduc-
tion of SeO2 Oxidation Products according to the Method of
Gramatica et al. (1985). Preparation of (2RS,6RS)-2,6-Di-
methyloctane-1,8-diol (15) from (RS)-2,6-Dimethyl-2-octenal:
Ri (DB-Wax) 2455; Ri (DB-5) 1468; UV (MeOH) λmax 203 nm;
IR (NaCl) ν (cm-1) 3336 (OH), 2952, 2926, 1462, 1378, 1122,
1054, 906, 847; 1H NMR (250 MHz, CDCl3) δ 0.90 (3H, d, J )
6.5 Hz, Me-C6), 0.92 (3H, d, J ) 6.5 Hz, Me-C2), 1.03-1.70
(10H, m, H2, H23, H24, H25, H6, H27), 3.41 (1H, dd, J ) 10.5,
6.0 Hz, H1a), 3.51 (1H, dd, J ) 10.5, 6.0 Hz, H1b), 3.64 (1H,
ddd, J ) 10.5, 6.5, 6.5 Hz, H8a), 3.70 (1H, ddd, J ) 10.5, 7.0,
7.0 Hz, H8b); 13C NMR (63 MHz, CDCl3) δ 16.5/16.6 (Me-C2),
19.6/19.7 (Me-C6), 24.2 (C4), 29.3/29.4 (C6), 33.2/33.3 (C3),
35.7/35.7 (C2), 37.2/37.3 (C5), 39.8/39.9 (C7), 61.1 (C8), 68.3
(C1).
1
(CdC), 1468, 1371, 1163, 997 and 920 (-CHdCH2), 756; H
NMR (250 MHz, CDCl3) δ 1.20 (6H, s, 2Me-C2), 1.28 (3H, s,
Me-C6), 1.47 (6H, m, H23, H24, H25), 5.03 (1H, dd, J ) 11.0,
1.5 Hz, H8a), 5.20 (1H, dd, J ) 17.5, 1.5 Hz, H8b), 5.91 (1H,
dd, J ) 17.5, 11.0 Hz, H7); 13C NMR (63 MHz, CDCl3) δ 18.5
(C4), 27.6 (Me-C6), 29.1 (Me-C2), 29.1 (Me-C2), 42.6 (C5), 44.0
(C3), 70.9 (C2), 73.1 (C6), 111.5 (C8), 145.1 (C7).
(3RS)-3,7-Dimethyl-6-octene-1,3-diol (21) from Geraniol: Ri
(DB-Wax) 2264; Ri (DB-5) 1393; UV (MeOH) λmax 205 nm; IR
(NaCl) ν (cm-1) 3357, 2968, 2926, 1644 (CdC), 1453, 1376,
1
1162, 1119, 1060, 1029, 934, 835 (>CdCH-); H NMR (360
MHz, CDCl3) δ 1.26 (3H, s, Me-C3), 1.56 (2H, m, H24), 1.63
(3H, br s, Me-C7), 1.67 (1H, ddd, J ) 14.5, 6.5, 4.5 Hz, H2a),
1.69 (3H, d, J ) 1.0 Hz, Me-C7), 1.81 (1H, ddd, J ) 14.5, 7.5,
4.5 Hz, H2b), 2.06 (2H, m, H25), 3.86 (1H, ddd, J ) 11.0, 6.5,
4.5 Hz, H1a), 3.92 (1H, ddd, J ) 11.0, 7.5, 4.5 Hz, H1b), 5.15
(1H, tqq, J ) 7.0, 1.0, 1.0 Hz, H6); 13C NMR (63 MHz, CDCl3)
δ 17.6 (Me-C7), 22.7 (C5), 25.6 (Me-C7), 26.6 (Me-C3), 41.5
(C2), 42.3 (C4), 59.7 (C1), 73.8 (C3), 124.2 (C6), 131.9 (C7).
Mu ltid im en sion a l Ga s Ch r om a togr a p h y (MDGC). For
MDGC two Carlo Erba GC 8000 coupled via an MCSS column
switching device and a heated transfer line (200 °C) were
applied. Split/splitless injector (splitless mode, 210 °C) and
flame ionization detectors (FID) on each oven (240 °C) were
used. The pressures for the detector gases were 0.5 bar of
hydrogen and 1.5 bar of air. Hydrogen was used as carrier
gas at a pressure of 1.5 bar for column 1 and 0.8 bar for column
2. Preseparation was achieved in oven 1 on an Innowax-20M
fused silica capillary column (38 m × 0.25 mm i.d.; film
thickness ) 0.5 µm). The temperature was programmed from
50 °C (5 min isotherm) to 235 °C at 4 °C/min. An MCSS
column switching device in oven 1 was used to perform effluent
cuts onto the chiral column in oven 2 [6-(tert-butyldimethyl-
silyl)-2,3-dimethyl-â-cyclodextrin in SE 54; 30 m × 0.25 mm
i.d., film thickness ) 0.25 µm]. The temperature in oven 2
was 70 °C for 20 min; it was then increased to 130 °C at 2
°C/min and from 130 °C the rate was 10 °C/min up to 210 °C.
One effluent cut from 18.6 to 19.9 min was carried out to
transfer the cis- and trans-rose oxides 1a /b onto the chiral
column.
(2RS,6RS)-2,6-Dimethyl-7-octene-1,6-diol (16) from (RS)-6-
Acetoxy-2,6-dimethylocta-2,7-dienal: Ri (DB-Wax) 2227; Ri (DB-
5) 1346; UV (MeOH) λmax 204 nm; IR (NaCl) ν (cm-1) 3360
(OH), 3086, 2934, 1463, 1411, 1371, 1154, 1038, 996 and 919
1
(-CHdCH2); H NMR (360 MHz, CDCl3) δ 0.91 (3H, d, J )
7.0 Hz, Me-C2), 1.10-1.66 (7H, m, H2, H23, H24, H25), 1.28
(3H, s, Me-C6), 3.42 (1H, dd, J ) 10.5, 6.0 Hz, H1a), 3.49 (1H,
dd, J ) 10.5, 6.0 Hz, H1b), 5.04 (1H, dd, J ) 11.0, 1.0 Hz, H8a),
5.20 (1H, dd, J ) 18.0, 1.0 Hz, H8b), 5.91 (1H, dd, J ) 11.0,
18.0 Hz, H7); 13C NMR (63 MHz, CDCl3) δ 16.6 (Me-C2), 21.2
(C4), 27.7/27.8 (Me-C6), 33.5 (C3), 35.7 (C2), 42.5 (C5), 68.2
(C1), 73.2 (C6), 111.6 (C8), 145.1/145.2 (C7).
(7RS)-(2E)-3,7-Dimethyl-2-octene-1,8-diol (17) from (2E,6E)-
2,6-Dimethyl-8-hydroxyocta-2,6-dienal: Ri (DB-Wax) 2555; Ri
(DB-5) 1518; UV (MeOH) λmax 203 nm; IR (NaCl) ν 3347 (OH),
2952, 2929, 2872, 1668 (CdC), 1462, 1379, 1216, 1030, 757,

Oxygenated Terpenoids from Rose Petals
J. Agric. Food Chem., Vol. 46, No. 5, 1998 1969
F igu r e 1. Protocol for the isolation and separation of aroma
precursors from rose flowers.
F igu r e 2. Acid-catalyzed conversion of (S)-3,7-dimethyl-5-
octene-1,7-diol (2) into isomeric rose oxides 1a /b.
Ca p illa r y Ga s Ch r om a t ogr a p h y/Ma ss Sp ect r om et r y
(GC/MS). GC/MS was performed with a Hewlett-Packard
GCD system equipped with a PTV injector (KAS system,
Gerstel, Mu¨lheim, Germany). The system was equipped with
a J &W fused silica DB-5 capillary column (30 m × 0.25 mm
i.d., film thickness ) 0.25 µm). The temperature program was
from 60 °C (2 min isothermal) to 300 °C at 5 °C/min. The flow
rate of the carrier gas was 1.0 mL/min He. Other conditions
were as follows: temperature of ion source, 180 °C; electron
energy, 70 eV. The linear retention index (Ri) is based on a
series of n-hydrocarbons.
F igu r e 3. Structures of monoterpene diols 2-22 identified
in a polar extract of rose flowers.
Nu clea r Ma gn etic Reson a n ce (NMR). 1H and 13C NMR
spectral data were recorded on Fourier transform Bruker AM
360 and AC 250 spectrometers with TMS as internal reference
standard.
hydroxylated monoterpenoids, so-called “polyols”. In an
effort to further separate the diethyl ether extract, an
additional MLCCC fractionation with n-BuOH/MeOH/
H2O (10:1:10) as solvent system was carried out. Due
to the complexity of the Et2O isolate (≈50 different
compounds), further workup by flash chromatography
and purification by HPLC were necessary. In this way,
four oxygenated monoterpenes (2, 12, 13, and 21) could
be isolated, and their structures were elucidated by
NMR spectroscopy. Importantly, the isolated com-
pounds included 3,7-dimethyl-5-octene-1,7-diol (2), the
known synthetic precursor of isomeric rose oxides 1a /b
(Ohloff et al., 1961). The configuration at the stereo-
genic center C-3 of rose oxide precursor 2, which has
for the first time been isolated from a natural source,
was determined by acid-catalyzed conversion of diol 2
into isomeric rose oxides 1a /b. Since chiral MDGC
analysis [Innowax-20M/6-(tert-butyldimethylsilyl)-2,3-
dimethyl-â-cyclodextrin] revealed 2S,4R and 2R,4R
RESULTS AND DISCUSSION
An aroma precursor isolate has been obtained from
rose flowers by MeOH extraction and subsequent XAD-2
adsorption chromatography (see Figure 1). Elution with
methanol yielded 40 g of a precursor concentrate, which
was prefractionated by MLCCC. Sequential fractions
from the MLCCC separation were pooled into five
groups. Aliquots of these grouped fractions I-V were
then subjected to SDE (pH 2.5). Upon SDE, the major
portion of rose oxide (80% of total) was observed from
the least polar fraction V; the remaining 20% were
produced upon heating of MLCCC fraction III. Extrac-
tion of fraction V with diethyl ether and subsequent GC/
MS analysis revealed that this fraction contains poly-

1970 J. Agric. Food Chem., Vol. 46, No. 5, 1998
Knapp et al.
Ohloff, G.; Klein, E.; Schenck, G. O. Syntheses of rose oxides
and further hydropyrane derivatives via photohydroperox-
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Ohloff, G.; Giersch, W.; Schulte-Elte, K. H.; Enggist, P.;
Demole, E. Synthesis of (R)- and (S)-4-methyl-6-2′-methyl-
prop-1′-enyl-5,6-dihydro-2H-pyran (nerol oxide) and natural
occurrence of its racemate. Helv. Chim. Acta 1980, 63,
1582-1597.
configurations for cyclic ethers 1a /b, the configuration
of precursor diol 2 was assigned as S (Figure 2).
In addition to isolated diols 2, 12, 13, and 21, 17
structurally related compounds could be identified by
GC/MS analyses and comparison of the mass spectral
data with those of authentic references (see Figure 3).
With regard to the odor contribution of these diols, the
precursor role of diol 7 must also be stressed. Under
acidic conditions cyclization gives rise to isomeric nerol
oxides, which are known odoriferous constituents of rose
essential oil (Ohloff and Demole, 1987).
P r ecu r sor F u n ction of Mon oter p en e Diols. Poly-
hydroxylated terpenoids (polyols) together with the well-
known terpene glycoconjugates (Winterhalter and
Skouroumounis, 1997) have been found to be involved
in the generation of volatile compounds. The specific
role of polyols in the acid-catalyzed production of vola-
tiles in fruits and wine has been the subject of several
reviews (Rapp et al., 1984; Williams et al., 1985; Strauss
et al., 1986). With regard to rose polyols, only the
identification of diols 3 and 21 has so far been reported
(Ohloff et al., 1980, 1985). The remaining 19 diols are
to the best of our knowledge reported in rose flowers
for the first time. It is furthermore noteworthy that the
structures of five additional diols remain to be eluci-
dated. In view of the reactivity of terpene diols and the
well-recognized aroma properties of the volatiles formed,
their contribution to rose odor has obviously been
underestimated. Concerning the formation of rose
oxides in rose essential oil, it can be concluded that a
major portion of isomeric ethers 1a /b is chemically
formed from the acid labile progenitor 2 during the
steam distillation process. The isolation and structure
elucidation of the additional precursor of cyclic ethers
1a /b from MLCCC fraction III is the subject of ongoing
research.
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Straubinger, M.; J ezussek, M.; Waibel, R.; Winterhalter, P.
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Surburg, H.; Guentert, M.; Harder, H. Volatile compounds
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ACKNOWLEDGMENT
We thank Dr. R. Waibel and Mrs. M. Unzeitig for
recording the NMR spectra. We are indebted to Dr. H.-
G. Schmarr, Technical University of Mu¨nchen-Weihen-
stephan, for MDGC analyses.
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Received for review November 18, 1997. Revised manuscript
received February 16, 1998. Accepted February 19, 1998.
J F970987X