PAPER
(1R)-3-endo-(p-Methoxybenzyl)isobornyl-Propionate
1395
19.3 (C8), 12.80 ( -CH3; isomer A*), 12.79 ( -CH3; isomer B*),
11.5 (C10), 7.7 (C5 ).
EIMS: m/z (%) = 386 (M+, 33), 344 (15), 273 (29), 272 (81), 257
(1R,2R,3S,4R)-3-[(4-Methoxyphenyl)methyl]-1,7,7-trimethylbi-
cyclo[2.2.1]hept-2-yl Esters of (R)-2-Methylhexanoic Acid (5b)
and (S)-2-Methylhexanoic Acid (6b)
IR: 2948, 1731, 1613, 1513, 1461, 1248, 1178, 1038, 837 cm–l.
(47), 256 (87), 161 (64), 160 (91), 135 (98), 134 (63), 121 (100).
1H NMR: = 7.05 (d, 2 H, J = 8.6 Hz, ArH), 6.77 (d, 2 H, J = 8.6
Hz, ArH), 4.49 (d, 1 H, J = 4.0 Hz, C2-H), 3.74 (s, 3 H, OCH3), 2.82
(dd, 1 H, J = 7.3, 13.6 Hz, C1 -HS; S ester), 2.81 (dd, 1 H, J = 7.3,
13.6 Hz, C1 -HS; R ester), 2.57 (dd, 1 H, J = 8.8, 13.6 Hz, C1 -HR),
2.3l (complex, 1 H, C3-H), 2.26 (sextet, 1 H, J = 7.2 Hz, C2 -H),
1.10–1.7 (complex, 7 H, C4-H, C5-H, C6-H, C3 -H), 1.03 (d, 3 H,
J = 7.0 Hz, -CH3; S ester), 1.004 (d, 3 H, J = 6.9 Hz, -CH3; R es-
ter), 1.00 (s, 3 H, C10-H), 0.87 (t, 3 H, J = 6.3 Hz, CH3), 0.83 (s, 3
H, C9-H), 0.76 (s, 3 H, C8-H).
13C NMR: = 175.9 (C=O), 157.7 (C4 ), 133.2 (Cl ), 129.5 (C2 ),
113.7 (C3 ), 85.4 (C2), 55.1 (OCH3), 49.9 (Cl), 49.3 (C4), 48.2
(C3), 47.7 (C7), 39.9 (C2 ), 35.9 (C6), 34.1 (C5), 33.3 (C3 ), 29.4
(C4 ), 22.6 (C5 ), 20.4 (C9), 20.2 (C1 ), 19.4 (C8), 17.l ( -CH3),
13.9 (C6 ), 11.6 (C10).
HRMS-EI: m/z calcd for C24H34O4: 386.2457; found: 386.2458
(Dev. 0.3 ppm).
HPLC purification of the less polar fraction from column chroma-
tography gave two fractions. The less polar material obtained by
HPLC was a colorless oil (0.10 g, 11%) and identified as 7a.
(1R,2R,3S,4R)-3-[(4-Methoxyphenyl)methyl]-1,7,7-trimethylbi-
cyclo[2.2.1]hept-2-yl 2-Ethyl-2-methylbutanoate (7a)
IR: 2952, 1723, 1614, 1513, 1460, 1300, 1248, 1150, 1039, 840,
702 cm–l.
1H NMR: = 7.04 (d, 2 H, J = 8.7 Hz, ArH), 6.79 (d, 2 H, J = 8.7
Hz, ArH), 4.46 (d, 1 H, J = 3.8 Hz, C2-H), 3.77 (s, 3 H, OCH3), 2.92
(dd, 1 H, J = 6.1, 13.7 Hz, C1 -HR), 2.57 (dd, 1 H, J = 10.0, 13.7 Hz,
C1 -HS), 2.37 (complex, 1 H, C3-H), 1.10–1.7 (complex, 9 H, C4-
H, C5-H, C6-H, C3 -H), 1.02 (s, 3 H, -CH3), 1.00 (s, 3 H, C10-
H), 0.83 (s, 3 H, C9-H), 0.80 (t, 3 H, J = 7.4 Hz, CH3), 0.78 (t, 3 H,
J = 7.4 Hz, CH3), 0.78 (s, 3 H, C8-H).
EIMS: m/z (%) = 386 (M+, 31), 256 (100), 161 (45), 160 (91), 159
(12), 134 (12), 122 (20), 121 (65), 85 (21).
HRMS-EI: m/z calcd for C25H38O3: 386.2821; found: 386.2824
(Dev. 0.9 ppm).
13C NMR: = 176.7 (C=O), 157.6 (C4 ), 133.3 (Cl ), 129.5 (C2 ),
113.7 (C3 ), 85.3 (C2), 55.1 (OCH3), 49.7 (Cl), 49.6 (C4), 47.6
(C3), 46.5 (C7), 35.6 (C6), 34.1 (C5), 31.5 (C2 ), 31.3 (C3 ), 20.5
(C-9), 20.1 (C-1, -CH3), 19.4 (C8), 11.8 (C10), 8.9 (C4 ).
The less polar material obtained by HPLC was a colorless oil (0.03
g, 4%) identified as 7b.
(1R,2R,3S,4R)-3-[(4-Methoxyphenyl)methyl]-1,7,7-trimethylbi-
cyclo[2.2.1]hept-2-yl 2-butyl-2-methyl Hexanoate (7b)
IR: 2949, 1725, 1614, 1512, 1465, 1249, 1205, 1178, 1151, 1040,
976, 838, 701 cm-l.
1H NMR: = 7.04 (d, 2 H, J = 8.5 Hz, ArH), 6.79 (d, 2 H, J = 8.5
Hz, ArH), 4.44 (d, 1 H, J = 3.7 Hz, C2-H), 3.77 (s, 3 H, OCH3), 2.96
(dd, 1 H, J = 5.5, 13.8 Hz, C1 -HS), 2.56 (dd, 1 H, J = 10.4, 13.7 Hz,
C1 -HR), 2.3l (complex, 1 H, C3-H), 1.10–1.70 (complex, 17 H, C4-
H, C5-H, C6-H, C3 -H, C4 -H, C5 -H), 1.05 (s, 3 H, CH3), 0.99
(s, 3 H, C10-H), 0.88 (t, 3 H, J = 6.9 Hz, CH3), 0.83 (s, 3 H, C9-H),
0.78 (s, 3 H, C8-H).
13C NMR: = 177.0 (C=O), 157.6 (C4 ), 133.4 (Cl ), 129.5 (C2 ),
113.6 (C3 ), 85.4 (C2), 55.2 (OCH3), 49.7(C4), 49.67 (C2 ), 47.6
(Cl), 47.4 (C3), 45.8 (C7), 39.3 (C3 ), 35.4 (C6), 34.1 (C5), 26.8
(C4 ), 23.3 (C5 ), 21.l ( -CH3), 20.5 (C9), 20.1 (C1 ), 19.4 (C8),
14.1 (C6 ), 11.8 (C10).
EIMS: m/z (%) = 386 (M+, 8), 272 (27), 262 (28), 256 (29), 231
(26), 160 (66), 149 (28),135 (21), 121 (42), 109 (62).
HRMS-EI: m/z calcd for C25H3803: 386.2821; found: 386.2828
(Dev. 1.9 ppm).
The more polar material obtained by HPLC was a colorless oil (0.55
g, 60%) and identified as a 71:29 mixture 5a and 6a.
(1R,2R,3S,4R)-3-[(4-Methoxyphenyl)methyl]-1,7,7-trimethylbi-
cyclo[2.2.1]hept-2-yl Esters of (R)-2-Methylbutanoic Acid (5a)
and (S)-2-Methylbutanoic Acid (6a)
IR: 2963, 1731, 1613, 1512, 1462, 1245, 1179, 1152, 1037, 835
cm–1.
1H NMR: = 7.06 (d, 2 H, J = 8.5 Hz, ArH), 6.78 (d, 2 H, J = 8.5
Hz, ArH), 4.49 (d, 1 H, J = 4.0 Hz, C2-H), 3.75 (s, 3 H, OCH3), 2.82
(dd, 1 H, J = 7.5, 13.7 Hz, C1 -HS; S ester), 2.81 (dd, 1 H, J = 7.5,
13.7 Hz, C1 -HS; R ester), 2.57 (dd, 1 H, J = 8.4, 13.6 Hz, C1 -HR),
2.37 (complex, 1 H, C3-H), 2.22 (sextet, 1 H, J = 7.0 Hz, C2 -H),
1.10–1.7 (complex, 7 H, C4-H, C5-H, C6-H, C3 -H), 1.03 (d, 3 H,
J = 6.9 Hz, -CH3 S ester), 1.00 (s, 3 H, C10-H), 0.834 (t, 3 H,
J = 7.5 Hz, CH3), 0.83 (s, 3 H, C9-H), 0.75 (s, 3 H, C8-H).
EIMS: m/z (%) = 442 (M+, 4), 256 (10), 210 (61), 168 (40), 105
(36), 91 (100).
HRMS-EI: m/z calcd for C29H46O3: 442.3447; found: 442.3458
(Dev. 2.6 ppm).
13C NMR: = 176.0 (C=O), 157.9 (C4 ), 133.4 (Cl ), 129.6 (C2 ),
113.7, (C3 ), 85.1 (C2), 55.0 (OCH3), 49.7 (Cl), 49.1 (C4), 48.0
(C7), 47.5 (C3), 41.3 (C2 ), 35.7 (C6), 33.9 (C5), 26.4 (C3 ), 20.2
(C9), 19.9 (C1 ), 19.2 (C8), 16.3 ( -CH3), 11,3 (C10, C4 ).
ElMS: m/z (%) = 358 (M+, 28), 257 (10), 256 (47), 252 (14), 167
(15), 161 (33), 160 (85) 123 (58), 121 (62), 69 (62), 57 (100).
Alkylation with Isopropyl Bromide; Isolation of Products 5c
and 6c
The alkylation of the ester 3 (1.24 g, 3.64 mmol) with isopropyl bro-
mide (4.482 g, 36.4 mmol) by the general procedure yielded one
monoalkylation product which was purified by HPLC to give a col-
orless oil (0.34 g, 25%) identified as a 70:30 mixture of 5c and 6c,
respectively.
HRMS-EI: m/z calcd for C25H34O3: 358.2508; found: 358.2513
(Dev. 1.5 ppm).
(1R,2R,3S,4R)-3-[(4-Methoxyphenyl)methyl]-1,7,7-trimethylbi-
cyclo[2.2.1]hept-2-yl Esters of (R)-2,3-Dimethylbutanoic Acid
(5c) and (S)-2,3-Dimethylbutanoic Acid (6c)
Alkylation with n-Butyl Bromide; Isolation of Products 5b, 6b,
and 7b
The alkylation of the ester 3 (0.555 g, 1.68 mmol) with 1-bromobu-
tane (2.301 g, 16.8 mmol) by the general procedure yielded two
alkylation products which were separated by HPLC.
IR: 2961, 1730, 1513, 1249, 1179, 1041, 838 cm–1.
1H NMR: = 7.05 (d, 2 H, J = 8.4 Hz, ArH), 6.77 (d, 2 H, J = 8.4
Hz, ArH), 4.50 (d,1 H, J = 3.9 Hz, C2-H), 3.74 (s, 3 H, OCH3), 2.83
(dd, 1 H, J = 7.3, 13.6 Hz, C1 -H), 2.57 (dd, 1 H, J = 8.8, 13.6 Hz,
C1 -H), 2.36 (complex, 1 H, C3-H), 2.08 (sextet, I H, J = 7.0 Hz,
C2 -H), 1.82 (octet, 1 H, J = 7.0 Hz, C3 -H), 1.10–1.7 (complex,
The more polar material was a colorless oil (0.42 g, 65%) identified
as a 71:29 mixture of 5b and 6b.
Synthesis 2002, No. 10, 1391–1397 ISSN 0039-7881 © Thieme Stuttgart · New York