Syntheses, structures, and sensory characteristics of the perfume ingredient majantol and its analogs sila-majantol and germa-majantol: A study on C/Si/Ge bioisosterism

Article abstract of DOI:10.1021/om010816o

The perfume ingredient majantol [2,2-dimethyl-3-(3-methylphenyl)propan-1-ol (la)] and its silicon- and germanium-containing analogs sila-majantol [(hydroxymethyl)dimethyl(3-methylbenzyl)silane (1b)] and germa-majantol [(hydroxymethyl)dimethyl(3-methylbenzyl)-germane (1c)], respectively, were synthesized from i-PrC(O)Ph (four steps, → la), Me₂Si(CH ₂Cl)Cl (three steps, → 1b), or Cl₃GeCH₂Cl (four steps, → 1c). The structures of the C/Si/Ge analogs 1a/1b/1c were determined by crystal structure analyses and computational studies [RI-MP2 calculations (TZVP level)]. The odor of majantol (1a) was found to be strong fresh-floral, aqueous-aldehydic, and characteristic of lily-of-the-valley flowers, whereas that of sila-majantol (1b) was considerably less intense than that of la. It lacked the aqueous-aldehydic freshness, but possessed nevertheless the characteristic lily-of-the-valley odor, but it was more terpineol-like. The odor of germa-majantol (1c) was very weak and not characteristic; the majantol impression could be recognized only as a shade.

Full text of DOI:10.1021/om010816o

Organometallics 2002, 21, 113-120
113
Syn th eses, Str u ctu r es, a n d Sen sor y Ch a r a cter istics of
th e P er fu m e In gr ed ien t Ma ja n tol a n d Its An a logs
Sila -m a ja n tol a n d Ger m a -m a ja n tol: A Stu d y on C/Si/Ge
Bioisoster ism §
Reinhold Tacke,*,† Thomas Schmid,† Christian Burschka,† Martin Penka,† and
Horst Surburg‡
Institut fu¨r Anorganische Chemie, Universita¨t Wu¨rzburg, Am Hubland,
D-97074 Wu¨rzburg, Germany, and Haarmann & Reimer GmbH, Mu¨hlenfeldstraâe 1,
D-37601 Holzminden, Germany
Received September 10, 2001
The perfume ingredient majantol [2,2-dimethyl-3-(3-methylphenyl)propan-1-ol (1a )] and
its silicon- and germanium-containing analogs sila-majantol [(hydroxymethyl)dimethyl(3-
methylbenzyl)silane (1b)] and germa-majantol [(hydroxymethyl)dimethyl(3-methylbenzyl)-
germane (1c)], respectively, were synthesized from i-PrC(O)Ph (four steps, f 1a ),
Me2Si(CH2Cl)Cl (three steps, f 1b), or Cl3GeCH2Cl (four steps, f 1c). The structures of
the C/Si/Ge analogs 1a /1b/1c were determined by crystal structure analyses and computa-
tional studies [RI-MP2 calculations (TZVP level)]. The odor of majantol (1a ) was found to
be strong fresh-floral, aqueous-aldehydic, and characteristic of lily-of-the-valley flowers,
whereas that of sila-majantol (1b) was considerably less intense than that of 1a . It lacked
the aqueous-aldehydic freshness, but possessed nevertheless the characteristic lily-of-the-
valley odor, but it was more terpineol-like. The odor of germa-majantol (1c) was very weak
and not characteristic; the majantol impression could be recognized only as a shade.
In tr od u ction
material majantol (1a ), a commercial synthetic product5
with a muguet-type fragrance.6 We report here the syn-
theses of majantol (1a ), sila-majantol (1b), and germa-
majantol (1c) and their sensory characterization. The
Since the first report on sila-analogs of organic
perfume ingredients,1 a series of papers dealing with
silicon-2 and germanium-based2b,c,i,k fragrance materials
have been published. In context with our systematic
studies on C/Si/Ge bioisosterism (for a recent review,
see ref 3; for recent papers, see ref 4), we are investigat-
ing the effects of C/Si exchange (sila-substitution) and
C/Ge exchange (germa-substitution) in organic perfume
ingredients. As part of this project, we have studied the
effects of sila- and germa-substitution of the fragrance
§ Dedicated to Professor Edmund Lukevics on the occasion of his
65th birthday.
* To whom correspondence should be addressed.
† Universita¨t Wu¨rzburg.
‡ Haarmann & Reimer GmbH.
(1) Wrobel, D.; Tacke, R.; Wannagat, U.; Harder, U. Chem. Ber.
1982, 115, 1694-1704.
structures of these C/Si/Ge analogs were determined by
X-ray diffraction and computational methods. Prelimi-
nary results of these studies have been reported else-
where.7
(2) (a) Wrobel, D.; Wannagat, U. Liebigs Ann. Chem. 1982, 734-
738. (b) Wrobel, D.; Wannagat, U.; Harder, U. Monatsh. Chem. 1982,
113, 381-388. (c) Wrobel, D.; Wannagat, U. J . Organomet. Chem. 1982,
225, 203-210. (d) Wrobel, D.; Wannagat, U. Liebigs Ann. Chem. 1983,
211-219. (e) Mu¨nstedt, R.; Wannagat, U. Liebigs Ann. Chem. 1985,
944-949. (f) Wannagat, U.; Mu¨nstedt, R.; Harder, U. Liebigs Ann.
Chem. 1985, 950-958. (g) Mu¨nstedt, R.; Wannagat, U. Monatsh. Chem.
1985, 116, 693-700. (h) Wannagat, U.; Damrath, V.; Schliephake, A.;
Harder, U. Monatsh. Chem. 1987, 118, 779-788. (i) Tacke, R.;
Wiesenberger, F. Z. Naturforsch., B 1991, 46, 275-279. (j) Tang, S.;
Li, Y.; Cao, Y.; Wang, X. Chin. J . Chem. 1991, 9, 68-75; Chem. Abstr.
1991, 115, 29450a. (k) Wannagat, U.; Damrath, V.; Huch, V.; Veith,
M.; Harder, U. J . Organomet. Chem. 1993, 443, 153-165. (l) Tang, S.;
Xue, J .; Wu, J .; Cao, Y.; Zhi, J .; Wang, X. Chem. Res. Cin. Univ. 1993,
9, 121-126; Chem. Abstr. 1994, 121, 108909j. (m) Wannagat, U.;
Damrath, V.; Harder, U. Monatsh. Chem. 1994, 125, 1159-1169. (n)
Obara, R.; Olejniczak, T.; Wawrzen´czyk, C. J . Soc. Cosmet. Chem. 1995,
46, 321-328. (o) Obara, R.; Wawrzen´czyk, C. J . Cosmet. Sci. 1998,
49, 299-308. (p) Cao, Y.; Liu, Z. Yingyong Huaxue 1999, 16, 77-79;
Chem. Abstr. 2000, 132, 180622e. (q) Liu, Z.; Cao, Y. Gaodeng Xuexiao
Huaxue Xuebao 2000, 21, 1515-1519; Chem. Abstr. 2001, 134, 42184d.
(3) Tacke, R.; Heinrich, T.; Kornek, T.; Merget, M.; Wagner, S. A.;
Gross, J .; Keim, C.; Lambrecht, G.; Mutschler, E.; Beckers, T.; Bernd,
M.; Reissmann, T. Phosphorus, Sulfur Silicon 1999, 150/151, 69-87.
(4) (a) Tacke, R.; Reichel, D.; J ones, P. G.; Hou, X.; Waelbroeck, M.;
Gross, J .; Mutschler, E.; Lambrecht, G. J . Organomet. Chem. 1996,
521, 305-323. (b) Tacke, R.; Kosub, U.; Wagner, S. A.; Bertermann,
R.; Schwarz, S.; Merget, S.; Gu¨nther, K. Organometallics 1998, 17,
1687-1699. (c) Tacke, R.; Merget, M.; Bertermann, R.; Bernd, M.;
Beckers, T.; Reissmann, T. Organometallics 2000, 19, 3486-3497. (d)
Merget, M.; Gu¨nther, K.; Bernd, M.; Gu¨nther, E.; Tacke, R. J .
Organomet. Chem. 2001, 628, 183-194. (e) Tacke, R.; Kornek, T.;
Heinrich, T.; Burschka, C.; Penka, M.; Pu¨lm, M.; Keim, C.; Mutschler,
E.; Lambrecht, G. J . Organomet. Chem. 2001, 640, 140-165.
(5) Hafner, W.; Gebauer, H.; Regiert, M.; Ritter, P. Consortium fu¨r
elektrochemische Industrie GmbH, DE 3531585 A1, March 3 1987;
Chem. Abstr. 1987, 106, 156034g. Majantol is a registered trademark
of Haarmann & Reimer GmbH, Holzminden, Germany.
(6) For muguet materials, see: Rossiter, K. J . In Flavours and
Fragrances; Swift, K. A. D., Ed.; Royal Society of Chemistry: Cam-
bridge, UK, 1997; pp 21-35, and literature cited therein.
(7) Schmid, T.; Burschka, C.; Hofmann, M.; Penka, M.; Surburg, H.;
Tacke, R. 33rd Organosilicon Symposium; Saginaw, 2000, Abstract PB-
17.
10.1021/om010816o CCC: $22.00 © 2002 American Chemical Society
Publication on Web 12/05/2001

114 Organometallics, Vol. 21, No. 1, 2002
Tacke et al.
Resu lts a n d Discu ssion
dimethylsilane (6). Treatment of 6 with 3-methylbenzyl-
magnesium chloride in diethyl ether gave (chloromethyl)-
dimethyl(3-methylbenzyl)silane (7) (yield 65%), which
on reaction with sodium acetate in dimethylformamide
afforded (acetoxymethyl)dimethyl(3-methylbenzyl)silane
(8) (yield 69%). Treatment of 8 with lithium aluminum
hydride in diethyl ether, followed by hydrolysis, finally
gave (hydroxymethyl)dimethyl(3-methylbenzyl)silane
(sila-majantol, 1b) (yield 91%).
Syn th eses. Majantol (1a ) was prepared by a four-
step synthesis, starting from 2-methyl-1-phenylpro-
panone (2) (Scheme 1). Except for the last step [prepa-
ration of 1a (yield 89%) by treatment of 2,2-dimethyl-
3-(3-methylphenyl)propanoic acid with lithium aluminum
hydride in diethyl ether, followed by hydrolysis], all
reaction steps (2 f 3 f 4 f 5) were performed
according to ref 8.
Germa-majantol (1c) was prepared by a four-step
synthesis, starting from trichloro(chloromethyl)germane
(9) (Scheme 3). Treatment of 9 with 3-methylbenzyl-
Sch em e 1
Sch em e 3
Sila-majantol (1b) was prepared by a three-step syn-
thesis (Scheme 2), starting from chloro(chloromethyl)-
Sch em e 2
magnesium chloride in diethyl ether gave dichloro-
(chloromethyl)(3-methylbenzyl)germane (10) (yield 39%),
which on reaction with methyllithium in diethyl ether
afforded (chloromethyl)dimethyl(3-methylbenzyl)ger-
mane (11) (yield 90%). Treatment of 11 with sodium
acetate in dimethylformamide gave (acetoxymethyl)-
dimethyl(3-methylbenzyl)germane (12) (yield 87%). Sub-
sequent reduction with lithium aluminum hydride in
diethyl ether, followed by hydrolysis, finally yielded
(hydroxymethyl)dimethyl(3-methylbenzyl)germane (ger-
ma-majantol, 1c) (yield 86%).
Compounds 1a , 1b, 1c, 7, 8, and 10-12 were isolated
as colorless liquids. Their identities were established by
elemental analyses (C, H) and solution NMR studies
(1H, 13C, 29Si). In addition, the C/Si/Ge analogs 1a /1b/
1c were structurally characterized by single-crystal
X-ray diffraction studies.
Cr ysta l Str u ctu r e An a lyses. Compounds 1a , 1b,
and 1c were studied by single-crystal X-ray diffraction.
The silane 1b and the germane 1c crystallize in the
(8) Haller, A.; Bauer, E. Ann. Chim. 1918, 9, 21-27.

Sila-majantol and Germa-majantol
Organometallics, Vol. 21, No. 1, 2002 115
F igu r e 1. Molecular structure of 1a in the crystal (prob-
ability level of displacement ellipsoids 50%), showing the
atomic numbering scheme. Subsequent difference Fourier
maps showed the position of the oxygen-linked hydrogen
atom to be disordered between two positions. Both of
these positions revealed reasonable distances for poten-
tial O-H‚‚‚O hydrogen bonds [O1-H1 0.81(4), H1‚‚‚O1
1.91(4), O1‚‚‚O1 2.71(4) Å, O1-H1‚‚‚O1 169(4)°; O1-H1
0.78(4), H1‚‚‚O1 1.97(4), O1‚‚‚O1 2.73(4) Å, O1-H1‚‚‚O1
161(4)°],10 each resulting in an infinite (OH)x chain along
[0 0 1].
F igu r e 3. Molecular structures of the conformers 1c-R
(above) and 1c-â (below) in the crystal of 1c (probability
level of displacement ellipsoids 50%), showing the atomic
numbering scheme. The conformers form intermolecular
O-H‚‚‚O hydrogen bonds in the crystal [O1-H1 0.77(5),
H1‚‚‚O2 2.02(5), O1‚‚‚O2 2.755(4) Å, O1-H1‚‚‚O2 159(5)°;
O2-H2 0.90(5), H2‚‚‚O1 1.88(5), O2‚‚‚O1 2.766(3) Å, O2-
H2‚‚‚O1 170(5)°],10 resulting in an infinite (OH)x chain
along [0 0 1].
group C2/c,9 with a single molecule in the asymmetric
unit. The structures of 1a , 1b-R/1b-â, and 1c-R/1c-â in
the crystal are depicted in Figures 1-3. The crystal data
and the experimental parameters used for the crystal
structure analyses are summarized in Table 1. Selected
interatomic distances and angles are listed in Tables 2
and 3.
As can be seen from Figure 4 and Tables 2 and 3, the
respective Si/Ge-analogous conformers 1b-R (1b-â) and
1c-R (1c-â) are almost isostructural, and the structures
of the R-conformers are very similar to that of the
conformer found in the crystal of 1a . Thus, the struc-
tural chemistry of the C/Si/Ge analogs is characterized
by distinct similarities. This finding is supported by the
results obtained in the computational studies (see
below).
F igu r e 2. Molecular structures of the conformers 1b-R
(above) and 1b-â (below) in the crystal of 1b (probability
level of displacement ellipsoids 50%), showing the atomic
numbering scheme. These conformers form intermolecular
O-H‚‚‚O hydrogen bonds in the crystal [O1-H1 0.84(3),
H1‚‚‚O2 1.91(3), O1‚‚‚O2 2.7223(18) Å, O1-H1‚‚‚O2 160(3)°;
O2-H2 0.81(3), H2‚‚‚O1 1.92(3), O2‚‚‚O1 2.7345(18) Å, O2-
H2‚‚‚O1 176(2)°],10 resulting in an infinite (OH)x chain
along [0 0 1].
(9) The space group Cc is also consistent with the observed condi-
tions limiting possible reflections. With the space group C2/c, a
structural model could be easily obtained by direct methods and least
squares refinement. Subsequent difference Fourier maps showed the
position of the oxygen-linked hydrogen atom to be disordered between
two positions. Both of these positions revealed reasonable distances
for potential O-H‚‚‚O hydrogen bonds, each resulting in an infinite
(OH)x chain along [0 0 1]. This particular type of disorder for the OH
hydrogen atoms could not be completely resolved in the space group
Cc.
(10) In the case of 1a , the hydrogen-bonding system was analyzed
by using the program SHELXL-97: Sheldrick, G. M. SHELXL-97;
University of Go¨ttingen: Germany, 1997. In the case of 1b and 1c,
the hydrogen-bonding systems were analyzed by using the program
PLATON: Spek, A. L. PLATON; University of Utrecht: The Nether-
lands, 1998.
space group P21/c, with two molecules (conformers 1b-
R/1b-â and 1c-R/1c-â, respectively) in the asymmetric
unit. The crystal structures of these two compounds are
isotypic. The carbon analog 1a crystallizes in the space

116 Organometallics, Vol. 21, No. 1, 2002
Tacke et al.
Ta ble 1. Cr ysta l Da ta a n d Exp er im en ta l
P a r a m eter s for th e Cr ysta l Str u ctu r e An a lyses of
1a , 1b, a n d 1c
Ta ble 3. Selected In ter a tom ic Dista n ces (Å) a n d
An gles (d eg) for 1b-â a n d 1c-â
1b-â
Si2
1c-â
Ge2
1a
12H18
1b
1c
El
empirical
formula
formula mass,
g mol-1
collection T, K
λ(Mo KR), Å
cryst syst
space group
(no.)
C
O
C11H18OSi
C11H18GeO
El-C22
El-C23
El-C24
El-C25
1.8738(18)
1.854(2)
1.8567(19)
1.8842(18)
1.956(4)
1.933(4)
1.939(4)
1.961(4)
178.26
173(2)
0.71073
monoclinic
C2/c (15)
194.34
238.84
173(2)
0.71073
monoclinic
P21/c (14)
263(2)
0.71073
monoclinic
P21/c (14)
C22-El-C23
C22-El-C24
C22-El-C25
C23-El-C24
C23-El-C25
C24-El-C25
El-C25-C26
El-C22-O2
110.00(10)
110.87(10)
103.68(7)
110.60(9)
111.55(8)
109.95(9)
114.28(10)
113.41(11)
110.4(2)
110.5(2)
103.95(18)
111.14(18)
111.80(18)
108.83(18)
114.3(2)
a, Å
b, Å
c, Å
25.127(5)
9.784(2)
8.9928(18)
104.11(3)
2144.1(7)
8
9.7441(19)
27.492(6)
8.9331(18)
92.46(3)
2390.9(8)
8
9.774(2)
27.597(6)
9.0082(18)
91.26(3)
2429.3(8)
8
114.5(2)
â, deg
V, Å3
Z
D(calcd),
1.104
1.080
1.306
g cm-3
µ, mm-1
F(000)
0.068
784
0.161
848
2.486
992
cryst dimens,
mm
0.5 × 0.4 × 0.4 0.5 × 0.5 × 0.4 0.5 × 0.5 × 0.4
2θ range, deg
4.48-52.74
4.18-52.76
4.76-49.42
index ranges
-31 e h e 31, -12 e h e 11, -11 e h e 7,
-12 e k e 12, -27 e k e 34, -32 e k e 32,
-11 e l e 11
-11 e l e 11
13824
-10 e l e 10
11159
no. of collected 10881
reflns
no. of ind reflns 2181
4848
4115
Rint
no. of reflns
used
0.0513
2181
0.0504
4848
0.0782
4115
no. of params
128
1.079
247
0.973
248
0.938
Sa
F igu r e 4. Backbones of the conformers 1a , 1b-R, and 1c-R
(left) and the conformers 1b-â and 1c-â (right) in the
crystals of 1a , 1b, and 1c.
weight params 0.0698/0.6751 0.0742/0.0000 0.0573/0.0000
a/bb
R1c [I > 2σ(I)]
0.0440
0.0394
0.1142
0.0387
0.1004
wR2d(all data) 0.1262
conformational flexibility of the C/Si/Ge analogs 1a /1b/
1c. The conformations of the calculated minima14 of 1a ,
1b-R, and 1c-R (starting geometries derived from the
respective experimentally established conformations in
the crystal) are shown in Figure 5; the calculated
interatomic distances and angles are listed in Table 4.
As can be seen from Tables 2-4, the calculated struc-
tures are in good agreement with those established
experimentally.
The electrostatic potentials and the electron densities
of the C/Si/Ge analogs 1a /1b/1c were calculated with
the program GAUSSIAN 9815 (B3LYP16/TZVP level) by
using the respective minimum conformations 1a , 1b-R,
max./min.
residual
+0.279/-0.174 +0.234/-0.260 +0.506/-0.544
electron
density, e Å-3
S ) {∑[w(Fo - Fc2)2]/(n - p)}0.5; n ) no. of reflections; p )
a
2
no. of parameters. bw-1 ) σ2(Fo2) + (aP)2 + bP, with P ) [max
(Fo2, 0) + 2Fc2]/3. R1 ) ∑||Fo| - |Fc||/∑|Fo|. dwR2 ) {∑[w(Fo
-
c
2
Fc2)2]/∑[w(Fo2)2]}0.5
.
Ta ble 2. Selected In ter a tom ic Dista n ces (Å) a n d
An gles (d eg) for 1a , 1b-r, a n d 1c-r
1a
1b-R
Si1
1c-R
Ge1
El
C1
El-C2
El-C3
El-C4
El-C5
1.5225(17)
1.5272(17)
1.5266(17)
1.5475(17)
1.8823(17)
1.865(2)
1.8614(19)
1.8792(19)
1.951(3)
1.944(4)
1.940(4)
1.956(4)
(13) Program system TURBOMOLE: Ahlrichs, R.; Ba¨r, M.; Ha¨ser,
M.; Horn, H.; Ko¨mel, C. Chem. Phys. Lett. 1989, 162, 165-169.
(14) Calculated energies (C1 symmetry) [RI-MP2
energies (Hartree)]: 1a , -541.5862513; 1b-R, -792.6252565; 1c-R,
-2579.1622626.
+ E(vib0)
C2-El-C3
C2-El-C4
C2-El-C5
C3-El-C4
C3-El-C5
C4-El-C5
El-C5-C6
El-C2-O1
109.88(10)
107.18(10)
111.46(10)
108.91(10)
108.47(10)
110.91(10)
115.80(10)
113.39(11)
109.09(9)
106.99(8)
109.53(8)
111.25(11)
109.06(10)
110.87(8)
114.36(11)
111.06(10)
109.57(18)
107.16(16)
108.86(16)
111.1(2)
108.99(18)
111.08(18)
113.7(2)
(15) Frisch, M. J .; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J . R.; Zakrzewski, V. G.; Montgomery, J . A.,
J r.; Stratmann, R. E.; Burant, J . C.; Dapprich, S.; Millam, J . M.;
Daniels, A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J .;
Barone, V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo,
C.; Clifford, S.; Ochterski, J .; Petersson, G. A.; Ayala, P. Y.; Cui, Q.;
Morokuma, K.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;
Foresman, J . B.; Cioslowski, J .; Ortiz, J . V.; Baboul, A. G.; Stefanov,
B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts, R.;
Martin, R. L.; Fox, D. J .; Keith, T.; Al-Laham, M. A.; Peng, C. Y.;
Nanayakkara, A.; Gonzalez, C.; Challacombe, M.; Gill, P. M. W.;
J ohnson, B. G.; Chen, W.; Wong, M. W.; Andres, J . L.; Head-Gordon,
M.; Replogle, E. S.; Pople, J . A. Gaussian 98, revision A.7; Gaussian,
Inc.: Pittsburgh, PA, 1998.
111.0(2)
Com p u ta tion a l Stu d ies. RI-MP211 studies (TZVP12
level) with the program TURBOMOLE13 revealed a high
(11) (a) Weigend, F.; Ha¨ser, M. Theor. Chem. Acc. 1997, 97, 331-
340. (b) Weigend, F.; Ha¨ser, M.; Patzelt, H.; Ahlrichs, R. Chem. Phys.
Lett. 1998, 294, 143-152.
(12) Scha¨fer, A.; Huber, C.; Ahlrichs, R. J . Chem. Phys. 1994, 100,
5829-5835.
(16) (a) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785-
789. (b) Miehlich, B.; Savin, A.; Stoll, H.; Preuss, H. Chem. Phys. Lett.
1989, 157, 200-206. (c) Becke, A. D. J . Chem. Phys. 1993, 98, 5648-
5652.

Sila-majantol and Germa-majantol
Organometallics, Vol. 21, No. 1, 2002 117
F igu r e 5. Calculated structures of the conformers 1a ,
1b-R, and 1c-R.
Ta ble 4. Ca lcu la ted In ter a tom ic Dista n ces (Å) a n d
An gles (d eg) for 1a , 1b-r, a n d 1c-r
1a
C1
1b-R
1c-R
El
Si1
Ge1
El-C2
El-C3
El-C4
El-C5
1.521
1.528
1.526
1.545
1.903
1.885
1.887
1.901
1.968
1.954
1.955
1.971
C2-El-C3
C2-El-C4
C2-El-C5
C3-El-C4
C3-El-C5
C4-El-C5
El-C5-C6
El-C2-O1
109.8
107.7
110.5
109.7
108.5
110.8
114.3
109.1
109.6
108.2
106.6
111.4
110.7
110.1
110.4
107.2
109.2
109.0
105.8
111.7
111.2
109.8
109.4
106.5
F igu r e 6. Electrostatic potentials ((0.08 au) mapped on
the calculated isosurfaces of the electron density (0.02 au)
of the conformers 1a (min. -0.074 au), 1b-R (min. -0.078
au), and 1c-R (min. -0.077 au).
jantol (1a ): strong fresh-floral, aqueous-aldehydic, and
characteristic of lily-of-the-valley flowers. The odor of
sila-majantol (1b) was found to be considerably less
intense than that of 1a . It lacked the aqueous-aldehydic
freshness, but possessed nevertheless the characteristic
lily-of-the-valley odor, but it was more terpineol-like.
The odor of germa-majantol (1c), on the other hand, was
very weak and not characteristic; the majantol impres-
sion could be recognized only as a shade. Compared to
the parent compound 1a , the sensory intensities of the
sila-analog 1b and the germa-analog 1c were consider-
ably less pronounced.
and 1c-R obtained in the RI-MP2 studies. The electro-
static potentials ((0.08 au) mapped on the calculated
isosurfaces of the electron density (0.02 au) are depicted
in Figure 6. According to these studies, sila- and germa-
substitution of majantol does not affect the electrostatic
potential significantly.
Sen sor y Ch a r a cter iza tion . The sensory properties
of the C/Si/Ge analogs 1a /1b/1c were determined using
10% solutions of the respective compounds in diethyl
ether applied to a blotter. The odor of 1a turned out to
be identical with that of the industrial standard ma-

118 Organometallics, Vol. 21, No. 1, 2002
Tacke et al.
H-4, H-6, C6H4), 7.11-7.17 (m, 1 H, H-5, C6H4). 13C NMR
(CDCl3): δ 21.4 (CCH3), 24.0 (CCH3), 36.4 (CC4), 44.6 (CCH2C),
71.2 (CCH2O), 126.7 (C-4 or C-6, C6H4), 127.5 (C-4 or C-6,
C6H4), 127.7 (C-5, C6H4), 131.2 (C-2, C6H4), 137.3 (C-1 or C-3,
C6H4), 138.7 (C-1 or C-3, C6H4). Anal. Calcd for C12H18O: C,
80.85; H, 10.18. Found: C, 80.8; H, 10.0.
P r ep a r a tion of (Hyd r oxym eth yl)d im eth yl(3-m eth yl-
ben zyl)sila n e (Sila -m a ja n tol, 1b). A solution of 8 (3.07 g,
13.0 mmol) in diethyl ether (25 mL) was added dropwise at 0
°C over a period of 30 min to a stirred suspension of LAH (980
mg, 25.8 mmol) in diethyl ether (11 mL). The mixture was
stirred for 1 h at room temperature and then added to a
mixture of 2 M hydrochloric acid (70 mL) and diethyl ether
(30 mL) at 0 °C. The organic phase was separated and the
aqueous layer extracted with diethyl ether (20 mL). The
combined organic extracts were dried over anhydrous Na2SO4,
the solvent was removed under reduced pressure, and the
residue was purified by Kugelrohr distillation (oven temper-
ature 100 °C, 0.01 mbar) to give 1b in 91% yield as a colorless
liquid (2.29 g, 11.8 mmol). 1H NMR (CDCl3): δ 0.04 (s, 6 H,
SiCH3), 1.07 (s, 1 H, OH), 2.14 (s, 2 H, SiCH2C), 2.30 (s, 3 H,
CCH3), 3.38 (s, 2 H, SiCH2O), 6.83-6.91 (m, 3 H, H-2, H-4,
H-6, C6H4), 7.09-7.14 (m, 1 H, H-5, C6H4). 13C NMR (CDCl3):
δ -5.3 (SiCH3), 21.4 (CCH3), 23.5 (SiCH2C), 54.7 (SiCH2O),
124.9 (C-4 or C-6, C6H4), 125.0 (C-4 or C-6, C6H4), 128.2 (C-5,
C6H4), 128.8 (C-2, C6H4), 137.8 (C-1 or C-3, C6H4), 139.5 (C-1
or C-3, C6H4). 29Si NMR (CDCl3): δ -0.1. Anal. Calcd for
F igu r e 7. Gas chromatogram obtained with a mixture of
the C/Si/Ge analogs 1a /1b/1c (see Experimental Section).
Due to the different covalent radii of carbon, silicon,
and germanium, the majantol, sila-majantol, and germa-
majantol molecules differ somewhat in their size, but
the structural chemistry of these C/Si/Ge analogs is
characterized by strongly pronounced similarities. Their
electrostatic potentials are also very similar. Despite all
of these similarities, significant differences in their
sensory properties were observed. These differences may
be explained by the different volatilities of compounds
1a , 1b, and 1c (1a > 1b > 1c). These different vola-
tilities are clearly reflected by the gas chromatogram
shown in Figure 7.
C
11H18OSi: C, 67.98; H, 9.34. Found: C, 67.6; H, 9.3.
P r ep a r a tion of (Hyd r oxym eth yl)d im eth yl(3-m eth yl-
ben zyl)ger m a n e (Ger m a -m a ja n t ol, 1c). A solution of 12
(2.30 g, 8.19 mmol) in diethyl ether (20 mL) was added
dropwise at 0 °C over a period of 30 min to a stirred suspension
of LAH (750 mg, 19.8 mmol) in diethyl ether (30 mL). The
mixture was stirred for 3 h at room temperature and then
added to a mixture of 2 M hydrochloric acid (40 mL) and
diethyl ether (20 mL) at 0 °C. The organic phase was separated
and the aqueous layer extracted with diethyl ether (10 mL).
The combined organic extracts were dried over anhydrous
Na2SO4, the solvent was removed under reduced pressure, and
the residue purified by Kugelrohr distillation (oven tempera-
ture 110 °C, 0.01 mbar) to give 1c in 86% yield as a colorless
liquid (1.69 g, 7.07 mmol). 1H NMR (CDCl3): δ 0.14 (s, 6 H,
GeCH3), 1.10 (s, 1 H, OH), 2.26 (s, 2 H, GeCH2C), 2.28 (s, 3 H,
CCH3), 3.60 (s, 2 H, GeCH2O), 6.81-6.88 (m, 3 H, H-2, H-4,
H-6, C6H4), 7.07-7.12 (m, 1 H, H-5, C6H4). 13C NMR (CDCl3):
δ -5.6 (GeCH3), 21.4 (CCH3), 23.4 (GeCH2C), 55.9 (GeCH2O),
124.6 (C-4 or C-6, C6H4), 124.9 (C-4 or C-6, C6H4), 128.3 (C-5,
C6H4), 128.4 (C-2, C6H4), 137.9 (C-1 or C-3, C6H4), 140.7 (C-1
or C-3, C6H4). Anal. Calcd for C11H18GeO: C, 55.31; H, 7.60.
Found: C, 55.2; H, 7.4.
Exp er im en ta l Section
Gen er a l P r oced u r es. All reactions were carried out under
dry nitrogen. Dimethylformamide (DMF) and diethyl ether
were dried and purified according to standard procedures and
stored under nitrogen. 1H, 13C, and 29Si NMR spectra were
recorded at 22 °C on a Bruker DRX-300 NMR spectrometer
(1H, 300.1 MHz; 13C, 75.5 MHz; 29Si, 59.6 MHz) using CDCl3
as solvent. Chemical shifts (ppm) were determined relative to
internal CHCl3 (1H, δ 7.24), internal CDCl3 (13C, δ 77.0), and
external TMS (29Si, δ 0). Assignment of the 13C NMR data was
supported by DEPT 135 and 13C HMQC experiments. The GC
studies were performed with a ThermoQuest gas chromato-
graph MS-8060 (J &W Scientifics DB-5MS capillary column,
30 m, i.d. 0.32 mm; injector, split (1:10), 225 °C; detector,
ThermoQuest mass spectrometer TRIO 1000, EI MS, 70 eV;
carrier gas, helium; temperature program, 80 °C (2 min) with
3 °C/min).
2-Meth yl-1-p h en ylp r op a n on e (2). This compound was
commercially available (Aldrich).
P r ep a r a t ion of 2,2-Dim et h yl-3-(3-m et h ylp h en yl)-1-
p h en ylp r op a n on e (3). This compound was synthesized ac-
cording to ref 8.
P r ep a r a tion of 2,2-Dim eth yl-3-(3-m eth ylp h en yl)p r o-
p a n a m id e (4). This compound was synthesized according to
ref 8.
P r ep a r a tion of 2,2-Dim eth yl-3-(3-m eth ylp h en yl)p r o-
p a n oic a cid (5). This compound was synthesized according
to ref 8.
P r ep a r a tion of 2,2-Dim eth yl-3-(3-m eth ylp h en yl)p r o-
p a n -1-ol (Ma ja n tol, 1a ). A solution of 5 (3.38 g, 17.6 mmol)
in diethyl ether (34 mL) was added dropwise at 0 °C over a
period of 30 min to a stirred suspension of lithium aluminum
hydride (LAH) (1.33 g, 35.0 mmol) in diethyl ether (15 mL).
The mixture was stirred for 1 h at room temperature and then
added to a mixture of 2 M hydrochloric acid (90 mL) and
diethyl ether (40 mL) at 0 °C. The organic phase was separated
and the aqueous layer extracted with diethyl ether (30 mL).
The combined organic extracts were dried over anhydrous
Na2SO4, the solvent was removed under reduced pressure, and
the residue was purified by Kugelrohr distillation (oven
temperature 87 °C, 0.01 mbar) to give 1a in 89% yield as a
Ch lor o(ch lor om et h yl)d im et h ylsila n e (6). This com-
pound was commercially available (ABCR).
P r ep a r a tion of (Ch lor om eth yl)d im eth yl(3-m eth ylben -
zyl)sila n e (7). A solution of 3-methylbenzyl chloride (15.0 g,
107 mmol) in diethyl ether (35 mL) was added dropwise over
a period of 30 min at -10 °C to a stirred suspension of
magnesium turnings (3.10 g, 128 mmol) in diethyl ether (5
mL). The mixture was stirred for 1 h at -10 °C and then added
dropwise within 30 min at room temperature to a stirred
solution of 6 (15.3 g, 107 mmol) in diethyl ether (80 mL). After
1
colorless liquid (2.78 g, 15.6 mmol). H NMR (CDCl3): δ 0.87
(s, 6 H, CCH3), 1.46 (s, 1 H, OH), 2.31 (s, 3 H, CCH3), 2.52 (s,
2 H, CCH2C), 3.30 (s, 2 H, CCH2O) 6.93-7.01 (m, 3 H, H-2,

Sila-majantol and Germa-majantol
Organometallics, Vol. 21, No. 1, 2002 119
the mixture was stirred for 16 h, water (100 mL) was added.
The phases were separated, and the aqueous layer was
extracted with diethyl ether (2 × 30 mL). The combined
organic extracts were dried over anhydrous Na2SO4, the
solvent was removed under reduced pressure, and the residue
was distilled in vacuo (115 °C, 10 mbar) to give 7 in 65% yield
under reduced pressure and the residue distilled in vacuo (0.01
mbar, 79 °C) to give 11 in 90% yield as a colorless liquid (2.80
1
g, 10.9 mmol). H NMR (CDCl3): δ 0.21 (s, 6 H, SiCH3), 2.29
(s, 3 H, CCH3), 2.31 (s, 2 H, GeCH2C), 2.89 (s, 2 H, GeCH2Cl),
6.81-6.90 (m, 3 H, H-2, H-4, H-6, C6H4), 7.08-7.13 (m, 1 H,
H-5, C6H4). 13C NMR (CDCl3): δ -5.1 (GeCH3), 21.4 (CCH3),
23.3 (GeCH2C), 29.8 (GeCH2Cl), 124.7 (C-4 or C-6, C6H4), 125.1
(C-4 or C-6, C6H4), 128.3 (C-5, C6H4), 128.5 (C-2, C6H4), 137.9
(C-1 or C-3, C6H4), 139.7 (C-1 or C-3, C6H4). Anal. Calcd for
1
as a colorless liquid (14.9 g, 70.0 mmol). H NMR (CDCl3): δ
0.12 (s, 6 H, SiCH3), 2.20 (s, 2 H, SiCH2C), 2.32 (s, 3 H, CCH3),
2.76 (s, 2 H, SiCH2Cl), 6.84-6.94 (m, 3 H, H-2, H-4, H-6, C6H4),
7.11-7.16 (m, 1 H, H-5, C6H4). 13C NMR (CDCl3): δ -4.9
(SiCH3), 21.4 (CCH3), 23.4 (SiCH2C), 29.6 (SiCH2Cl), 125.11
(C-4 or C-6, C6H4), 125.13 (C-4 or C-6, C6H4), 128.2 (C-5, C6H4),
128.9 (C-2, C6H4), 137.9 (C-1 or C-3, C6H4), 138.8 (C-1 or C-3,
C6H4). 29Si NMR (CDCl3): δ 3.0. Anal. Calcd for C11H17ClSi:
C, 62.09; H, 8.05. Found: C, 62.3; H, 8.0.
P r ep a r a tion of (Acetoxym eth yl)d im eth yl(3-m eth yl-
ben zyl)sila n e (8). A mixture of sodium acetate (2.83 g, 34.5
mmol) and 7 (5.00 g, 23.5 mmol) in DMF (50 mL) was stirred
for 3 days at 80 °C. After the mixture was cooled to room
temperature, water (35 mL) and diethyl ether (40 mL) were
added. The phases were separated, and the organic layer was
washed with water (2 × 10 mL) and then dried over anhydrous
Na2SO4. The solvent was removed under reduced pressure and
the residue distilled in vacuo (0.01 mbar, 70 °C) to give 8 in
69% yield as a colorless liquid (3.86 g, 16.3 mmol). 1H NMR
(CDCl3): δ 0.04 (s, 6 H, SiCH3), 2.02 (s, 3 H, CCH3), 2.12 (s, 2
H, SiCH2C), 2.28 (s, 3 H, C(O)CH3) 3.74 (s, 2 H, SiCH2O), 6.78-
6.90 (m, 3 H, H-2, H-4, H-6, C6H4), 7.07-7.12 (m, 1 H, H-5,
C6H4). 13C NMR (CDCl3): δ -5.0 (SiCH3), 20.7 (C(O)CH3), 21.4
(CCH3), 23.7 (SiCH2C), 56.1 (SiCH2O), 125.0 (C-4 or C-6, C6H4),
125.1 (C-4 or C-6, C6H4), 128.2 (C-5, C6H4), 128.9 (C-2, C6H4),
137.8 (C-1 or C-3, C6H4), 138.8 (C-1 or C-3, C6H4), 171.8 (CdO).
29Si NMR (CDCl3): δ 0.3. Anal. Calcd for C13H20O2Si: C, 66.05;
H, 8.53. Found: C, 66.4; H, 8.5.
C
11H17ClGe: C, 51.35; H, 6.66. Found: C, 51.6; H, 6.8.
P r ep a r a tion of (Acetoxym eth yl)d im eth yl(3-m eth yl-
ben zyl)ger m a n e (12). A mixture of sodium acetate (1.66 g,
20.2 mmol) and 11 (2.60 g, 10.1 mmol) in DMF (13 mL) was
heated under reflux for 5 h. After the mixture was cooled to
room temperature, water (10 mL) and diethyl ether (20 mL)
were added. The phases were separated, and the organic layer
was extracted with water (2 × 5 mL) and then dried over
anhydrous Na2SO4. The solvent was removed under reduced
pressure and the residue distilled in vacuo (0.01 mbar, 98 °C)
to give 12 in 87% yield as a colorless liquid (2.48 g, 8.83 mmol).
1H NMR (CDCl3): δ 0.15 (s, 6 H, GeCH3), 2.01 (s, 3 H,
C(O)CH3), 2.26 (s, 2 H, GeCH2C), 2.28 (s, 3 H, CCH3), 2.89 (s,
2 H, GeCH2Cl), 6.78-6.88 (m, 3 H, H-2, H-4, H-6, C6H4), 7.06-
7.11 (m, 1 H, H-5, C6H4). 13C NMR (CDCl3): δ -5.0 (GeCH3),
20.7 (C(O)CH3), 21.4 (CCH3), 23.8 (GeCH2C), 57.5 (GeCH2O),
124.8 (C-4 or C-6, C6H4), 125.0 (C-4 or C-6, C6H4), 128.2 (C-5,
C6H4), 128.5 (C-2, C6H4), 137.8 (C-1 or C-3, C6H4), 140.0 (C-1
or C-3, C6H4), 171.7 (CdO). Anal. Calcd for C13H20GeO2: C,
55.58; H, 7.18. Found: C, 55.2; H, 6.8.
Sin gle-Cr ysta l X-r a y Diffr a ction Stu d ies. Suitable single
crystals of 1a , 1b, and 1c were obtained by crystallization from
solutions in n-pentane at -20 °C. The crystals were mounted
in inert oil (perfluoroalkyl ether, ABCR) on a glass fiber and
then transferred to the cold nitrogen gas stream of the
diffractometer [Stoe IPDS; graphite-monochromated Mo KR
radiation (λ ) 0.71073 Å)]. The data for 1a and 1b were
collected at 173 K and the data for 1c at 263 K. Initial models
for the refinement of the structures of 1a , 1b, and 1c were
obtained by direct methods.18,19 All non-hydrogen atoms were
refined anisotropically.20 Hydrogen atoms could be located from
the peak lists of subsequent difference Fourier maps and were
refined using a riding model and geometrical recalculation at
ideal positions. Only those hydrogen atoms linked to the
oxygen atoms were refined freely with their temperature
factors tied to 1.5 times of the corresponding oxygen atom
temperature factors.
Com p u ta tion a l Stu d ies. RI-MP211 geometry optimizations
(TZVP12 level) of the C/Si/Ge analogs 1a /1b/1c were performed
using the TURBOMOLE program system.13 The experimen-
tally established conformations 1a , 1b-R, and 1c-R in the
crystal served as starting geometries for these calculations.
Each critical point of the respective potential energy surface
was characterized as a local minimum by calculation of the
vibrational frequencies. The calculated energies14 of 1a , 1b-R,
and 1c-R include the MP2 energies and the zero-point vibra-
tional energies obtained by SCF calculations. The electrostatic
potentials and electron densities of 1a , 1b -R, and 1c-R
(conformations obtained in the RI-MP2 calculations) were
calculated with the program GAUSSIAN 9815 using the DFT
method (B3LYP16/TZVP level).
Sen sor y Ch a r a cter iza tion . To get highly pure samples
for the sensory characterization, the NMR-spectroscopically
pure compounds 1a , 1b, and 1c were additionally purified by
thin-layer chromatography on silica gel (PLC plates, 20 × 20
cm, silica gel 60 F254, 1 mm; Merck, 1.13895) using n-hexane/
diethyl ether [10:1 (v/v)] as solvent. To remove traces of silica,
P r ep a r a tion of Tr ich lor o(ch lor om eth yl)ger m a n e (9).
This compound was synthesized according to ref 17a (see also
ref 17b).
P r ep a r a tion of Dich lor o(ch lor om eth yl)(3-m eth ylben -
zyl)ger m a n e (10). A solution of 3-methylbenzyl chloride (4.31
g, 30.7 mmol) in diethyl ether (20 mL) was added dropwise
over a period of 30 min at -10 °C to a suspension of magne-
sium turnings (751 mg, 30.9 mmol) in diethyl ether (5 mL).
The mixture was stirred for 1 h at this temperature and then
added dropwise within 30 min at room temperature to a stirred
solution of 9 (7.00 g, 30.6 mmol) in diethyl ether (40 mL). After
the mixture was stirred for 16 h at room temperature and
heated under reflux for 1 h, n-pentane (50 mL) was added.
The resulting precipitate was filtered off and washed with
n-pentane (2 × 20 mL). The filtrate and wash solutions were
combined, the solvent was removed under reduced pressure,
and the residue was distilled in vacuo (0.01 mbar, 90 °C) to
give 10 in 39% yield as a colorless liquid (3.60 g, 12.1 mmol).
1H NMR (CDCl3): δ 2.34 (s, 3 H, CCH3), 3.17 (s, 2 H, GeCH2C),
3.38 (s, 2 H, GeCH2Cl), 7.03-7.07 (m, 3 H, H-2, H-4, H-6, C6H4),
7.18-7.21 (m, 1 H, H-5, C6H4). 13C NMR (CDCl3): δ 21.4 (CCH3),
31.0 (GeCH2C), 32.5 (GeCH2Cl), 126.0 (C-4 or C-6, C6H4), 127.7
(C-4 or C-6, C6H4), 128.9 (C-5, C6H4), 129.7 (C-2, C6H4), 132.0
(C-1 or C-3, C6H4), 138.7 (C-1 or C-3, C6H4). Anal. Calcd for
C9H11Cl3Ge: C, 36.26; H, 3.72. Found: C, 36.4; H, 3.8.
P r ep a r a tion of (Ch lor om eth yl)d im eth yl(3-m eth ylben -
zyl)ger m a n e (11). A 1.6 M solution of methyllithium in
diethyl ether (15 mL, 24.0 mmol of MeLi) was diluted with
diethyl ether (20 mL) and the resulting solution then added
dropwise over a period of 45 min at -10 °C to a solution of 10
(3.60 g, 12.1 mmol) in diethyl ether (60 mL). The mixture was
stirred for 1 h at -10 °C and then warmed to room temper-
ature and stirred for another 3 h. The solvent was removed
(18) Sheldrick, G. M. SHELXS-97; University of Go¨ttingen: Ger-
many, 1997.
(17) (a) Tacke, R.; Becker, B. J . Organomet. Chem. 1988, 354, 147-
153. (b) Seyferth, D.; Rochow, E. G. J . Am. Chem. Soc. 1955, 77, 907-
910.
(19) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467-473.
(20) Sheldrick, G. M. SHELXL-97; University of Go¨ttingen: Ger-
many, 1997.

120 Organometallics, Vol. 21, No. 1, 2002
Tacke et al.
the compounds were afterward gently distilled in vacuo
(Kugelrohr apparatus). As demonstrated by GC studies, the
purities of the samples used for the sensory characterization
were >99.5%. The sensory properties were determined using
10% solutions of the respective compounds in diethyl ether
applied to a blotter.
anisotropic displacement parameters, experimental details of
the X-ray diffraction studies, and bond lengths and angles for
1a , 1b, and 1c. This material is available free of charge via
the Internet at http://pubs.acs.org. In addition, crystallographic
data (excluding structure factors) for the structures reported
in this paper have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication
nos. CCDC-160855 (1a ), CCDC-160856 (1b), and CCDC-
160857 (1c). Copies of the data can be obtained free of charge
on application to CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK [fax: (+44) 1223/336033; e-mail: deposit@ccdc.cam.ac.uk].
Ack n ow led gm en t. Financial support of this work
by the Fonds der Chemischen Industrie is gratefully
acknowledged.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and equivalent isotropic displacement parameters,
OM010816O