distilled crotyl bromide (E:Z ratio 9:1) as electrophile (2S,4R)-
2-ferrocenyl-3-pivaloyl-4-(but-2-enyl)-4-methyl-1,3-oxazolidin-5-
one 7c was obtained as brown crystals (2.25 g, 71%) with 92%
de and an E:Z ratio of 9:1; recrystallisation from Et2O–hexane
gave pure (2S,4R)-2-ferrocenyl-3-pivaloyl-4-[(E)-but-2-enyl]-4-
methyl-1,3-oxazolidin-5-one 7c; mp 114–118 ЊC; [α]D21 Ϫ91.0 (c
0.16, CHCl3); νmax(FT IR, KBr disc)/cmϪ1 2975m (C᎐H), 1783s
using 2-(bromomethyl)naphthalene as a solution in THF, which
was prepared by dissolving the electrophile in DCM, adding
THF and removing the DCM in vacuo, (2S,4R)-2-ferrocenyl-3-
pivaloyl-4-methyl-4-(2-naphthylmethyl)-1,3-oxazolidin-5-one 7f
was obtained as pale orange crystals (3.89 g, 95%) with >98%
de; mp 155–158 ЊC; [α]D23 Ϫ49.6 (c 1.05, CHCl3); νmax(FT IR, KBr
disc)/cmϪ1 2979w (C᎐H), 1783s (OC᎐O), 1647m (NC᎐O),
᎐
᎐
(OC᎐O), 1641s (NC᎐O), 1350m and 1182m; δ (500 MHz;
1348m, 1248m and 1172m; δH(200 MHz; CDCl3) 0.79 [9H, s,
C(CH3)3], 2.10 (3H, s, NCCH3), 3.36 (1H, d, J 13.5, CHAHB),
4.02 (1H, d, J 13.5, CHAHB), 4.22–4.30 (4H, m, Cp), 4.27 (5H,
s, CpЈ), 6.02 (1H, s, OCHN) and 7.26–7.85 (7H, m, C10H7);
δC(50.3 MHz; CDCl3) 23.63 (NCCH3), 28.01 [C(CH3)3], 40.85
[C(CH3)3], 41.33 (CH2), 66.50 (NCCH3), 67.96, 68.67, 69.24
and 69.33 (9 × CH in Cp and CpЈ), 86.82 (OCHN), 89.03
(quaternary C in Cp), 125.93, 126.31, 127.80, 127.90, 128.16
and 129.06 (7 × naphthalene CH), 132.75, 133.48 and 133.80
᎐
᎐
H
CDCl ) 1.04 [9H, s, C(CH ) ], 1.64 (3H, d, J 6.5, CH᎐CHCH ),
᎐
3
3
3
3
1.89 (3H, s, NCCH3), 2.45 (1H, dd, J 6, 14, CHAHB), 3.27 (1H,
dd, J 9, 14, CHAHB), 4.20–4.31 (4H, m, Cp), 4.27 (5H, s, CpЈ),
5.16 (1H, ddd, J 6, 9, 15, CH CH᎐CHCH ), 5.52 (1H, dd, J 6.5,
᎐
2
3
15, CH CH᎐CHCH ) and 6.64 (1H, s, OCHN); δ (125.7 MHz;
᎐
2
3
C
CDCl3) 18.00 and 22.85 (2 × CH3), 28.68 [C(CH3)3], 38.51
(CH2), 41.11 [C(CH3)3], 64.96 (NCCH3), 67.39, 68.07, 69.04
and 69.07 (4 × CH in Cp), 69.21 (5 × CH in CpЈ), 86.43
(OCHN), 89.96 (quaternary C in Cp), 124.25 and 130.59
(CH᎐CH), 175.71 and 175.86 (2 × C᎐O); m/z (APCIϩ) 424
(3 × quaternary naphthalene C), 176.02 and 176.79 (2 × C᎐O);
᎐
m/z (CI, NH3) 510 [(M ϩ H)ϩ, 100%], 102 [(C4H9CO ϩ NH3)ϩ,
63] and 85 [(C4H9CO)ϩ, 61] (Found: C, 70.75; H, 6.49; N, 2.93.
Calc. for C30H31NO3Fe: C, 70.73; H, 6.13; N, 2.75%).
᎐
᎐
[(M ϩ H)ϩ, 100%], 294 [(M Ϫ C4H9CO Ϫ CO2)ϩ, 49] and 199
[(FcCH2)ϩ, 24] [Found: C, 64.84; H, 6.87; N, 3.07. Calc. for
C23H29NO3Feؒ0.2H2O: C, 64.71; H, 6.94; N, 3.28%; HRMS:
found: 424.158 646; required for (M ϩ H)ϩ: 424.157 508 (ppm
Ϫ2.7)].
(2S,4R)-2-Ferrocenyl-3-pivaloyl-4-[1-(tert-butoxycarbonyl)-
indol-3-ylmethyl]-4-methyl-1,3-oxazolidin-5-one 7g. Starting
with 1.01 g of the oxazolidinone 5 and following the general
alkylation procedure using 1-(tert-butoxycarbonyl)-3-(bromo-
methyl)indole13 as a solution in THF as electrophile (2S,4R)-
2-ferrocenyl-3-pivaloyl-4-[1-(tert-butoxycarbonyl)indol-3-yl-
methyl]-4-methyl-1,3-oxazolidin-5-one 7g was obtained as beige
crystals (1.34 g, 82%) with 96% de; mp 146–149 ЊC; [α]D23 Ϫ101.0
(c 0.43, CHCl3); νmax(FT IR, KBr disc)/cmϪ1 2972m (C᎐H),
1789s (OC᎐O), 1726s (carbamate C᎐O), 1636s (NC᎐O), 1374s,
(2S,4R)-2-Ferrocenyl-3-pivaloyl-4-methyl-4-(2-methylbenzyl)-
1,3-oxazolidin-5-one 7d. Starting with 2.09 g of the oxazol-
idinone 5 and following the general alkylation procedure using
α-bromo-o-xylene as electrophile (2S,4R)-2-ferrocenyl-3-
pivaloyl-4-methyl-4-(2-methylbenzyl)-1,3-oxazolidin-5-one
7d
was obtained as yellow crystals (2.38 g, 89%) with 96% de; mp
155–157 ЊC; [α]D23 Ϫ180.1 (c 1.10, CHCl3); νmax(FT IR, KBr disc)/
cmϪ1 2970m (C᎐H), 1790s (OC᎐O), 1627s (NC᎐O), 1336s and
᎐
᎐
᎐
1178m and 1170m; δH(500 MHz; CDCl3) 0.84 [9H, s,
COC(CH3)3], 1.66 [9H, s, CO2C(CH3)3], 2.10 (3H, s, NCCH3),
3.31 (1H, d, J 14.5, CHAHB), 4.02 (1H, d, J 14.5, CHAHB),
4.20–4.29 (4H, m, Cp), 4.26 (5H, s, CpЈ), 6.22 (1H, s, OCHN),
7.22–7.37 (3H, m, 3 × indole CH), 7.64 (1H, d, J 8, indole CH)
and 8.15 (1H, d, J 8, indole CH); δC(125.7 MHz; CDCl3)
23.44 (NCCH3), 28.07 and 28.19 [2 × C(CH3)3], 31.72 (CH2),
40.79 [COC(CH3)3], 65.35 (NCCH3), 67.75, 68.68, 68.84 and
68.96 (4 × CH in Cp), 69.27 (5 × CH in CpЈ), 83.60 [CO2C-
(CH3)3], 86.74 (OCHN), 89.31 (quaternary C in Cp), 114.87,
120.16, 122.71, 124.44 and 125.47 (5 × indole CH), 130.20,
135.25 and 149.42 (3 × quaternary indole C), 176.08 and
176.20 (2 × C᎐O); m/z (CI, NH ) 599 [(M ϩ H)ϩ, 27%], 130
᎐
᎐
1177s; δH(200 MHz; CDCl3) 0.72 [9H, s, C(CH3)3], 2.08 (3H, s,
NCCH3), 2.36 (3H, s, C6H4CH3), 3.28 (1H, d, J 14.5, CHAHB),
3.82 (1H, d, J 14.5, CHAHB), 4.21–4.32 (4H, m, Cp), 4.29 (5H,
s, CpЈ), 6.33 (1H, s, OCHN) and 7.02–7.13 (4H, m, C6H4CH3);
δC(50.3 MHz; CDCl3) 19.63 and 24.28 (2 × CH3), 27.86
[C(CH3)3], 37.55 (CH2), 40.85 [C(CH3)3], 65.16 (NCCH3),
67.78, 68.79 and 68.94 (4 × CH in Cp), 69.31 (5 × CH in CpЈ),
86.93 (OCHN), 89.58 (quaternary C in Cp), 125.88, 126.93,
128.53 and 131.22 (4 × CH in C6H4), 134.93 and 138.18 (2 ×
quaternary C in C H ), 176.64 and 176.71 (2 × C᎐O); m/z (CI,
᎐
6
4
NH3) 474 [(M ϩ H)ϩ, 100%] and 344 [(M Ϫ COC4H9 Ϫ CO2)ϩ,
26] (Found: C, 68.77; H, 6.80; N, 2.80. Calc. for C27H31NO3Fe:
C, 68.51; H, 6.60; N, 2.96%).
᎐
3
[(C9H7N ϩ H)ϩ, 100] and 102 [(C4H9CO ϩ NH3)ϩ, 47] (Found:
C, 65.94; H, 6.35; N, 4.47. Calc. for C33H38N2O5Fe: C, 66.22;
H, 6.40; N, 4.68%).
(2S,4R,E)-2-Ferrocenyl-3-pivaloyl-4-cinnamyl-4-methyl-1,3-
oxazolidin-5-one 7e. Starting with 2.76 g of the oxazolidinone 5
and following the general alkylation procedure using cinnamyl
bromide as electrophile (2S,4R,E)-2-ferrocenyl-3-pivaloyl-4-
cinnamyl-4-methyl-1,3-oxazolidin-5-one 7e was obtained as
orange–brown crystals (3.41 g, 94%) with >98% de; mp 152–
155 ЊC; [α]D23 Ϫ145.2 (c 0.27, CHCl3); νmax(FT IR, KBr disc)/cmϪ1
(2S,4R)-2-Ferrocenyl-3-pivaloyl-4-cyanomethyl-4-methyl-1,3-
oxazolidin-5-one 7h. Starting with 1.64 g of the oxazolidinone 5
and following the general alkylation procedure using bromo-
acetonitrile as electrophile (2S,4R)-2-ferrocenyl-3-pivaloyl-4-
cyanomethyl-4-methyl-1,3-oxazolidin-5-one 7h was obtained as
light brown crystals (1.56 g, 86%) with 92% de; mp 131–135 ЊC;
2962m and 2930m (C᎐H), 1783s (OC᎐O), 1632s (NC᎐O),
᎐
᎐
1340s, 1242s and 1177s; δH(200 MHz; CDCl3) 1.00 [9H, s,
C(CH3)3], 1.97 (3H, s, NCCH3), 2.70 (1H, ddd, J 1.5, 6, 14,
CHAHB), 3.53 (1H, dd, J 9, 14, CHAHB), 4.21–4.31 (4H, m, Cp),
[α]D21 Ϫ230.0 (c 0.24, CHCl3); νmax(FT IR, KBr disc)/cmϪ1 2990m
᎐
and 2940m (C᎐H), 2248w (C᎐N), 1792s (OC᎐O), 1639s
᎐
᎐
(NC᎐O), 1397m, 1343s and 1193s; δ (200 MHz; CDCl ) 1.13
᎐
H
3
4.28 (5H, s, CpЈ), 5.93 (1H, ddd, J 6, 9, 15, CH CH᎐CH-
[9H, s, C(CH3)3], 1.95 (3H, s, NCCH3), 2.90 (1H, d, J 16.5,
CHAHB), 3.84 (1H, d, J 16.5, CHAHB), 4.20–4.38 (4H, m, Cp),
4.28 (5H, s, CpЈ) and 6.89 (1H, s, OCHN); δC(125.7 MHz;
CDCl3) 22.30 (NCCH3), 25.66 (CH2), 28.48 [C(CH3)3], 41.39
[C(CH3)3], 62.12 (NCCH3), 67.69, 68.19, 68.82 and 69.51
᎐
2
Ph), 6.45 (1H, d, J 15, CH CH᎐CHPh), 6.64 (1H, s, OCHN)
᎐
2
and 7.21–7.35 (5H, m, C6H5); δC(50.3 MHz; CDCl3) 22.83
(NCCH3), 28.62 [C(CH3)3], 38.97 (CH2), 41.10 [C(CH3)3], 65.05
(NCCH3), 67.53, 67.71, 68.19 and 69.15 (4 × CH in Cp), 69.30
(5 × CH in CpЈ), 86.67 (OCHN), 89.81 (quaternary C in Cp),
123.08, 126.38, 127.74, 128.79 and 135.15 (5 × CH in C6H5),
(4 × CH in Cp), 69.31 (5 × CH in CpЈ), 87.55 (OCHN), 88.74
᎐
(quaternary C in Cp), 115.56 (C᎐N), 173.17 and 177.20
᎐
137.01 (quaternary C in C H ), 175.99 and 176.43 (2 × C᎐O);
(2 × C᎐O); m/z (EI) 408 [(M)ϩ, 20%], 279 [(M Ϫ C H -
᎐
᎐
6
5
4
9
m/z (CI, NH3) 486 [(M ϩ H)ϩ, 18%], 215 [(FcCHO ϩ H)ϩ, 48],
199 [(FcCH2)ϩ, 51], 102 [(C4H9CO ϩ NH3)ϩ, 100] and 85
[(C4H9CO)ϩ, 53] (Found: C, 69.48; H, 6.67; N, 2.72. Calc. for
C28H31NO3Fe: C, 69.29; H, 6.44; N, 2.89%).
CO Ϫ CO2)ϩ, 36], 121 [(C5H5Fe)ϩ, 42] and 57 [(C4H9)ϩ, 100]
(Found: C, 61.99; H, 5.62; N, 6.69. Calc. for C21H24N2O3Fe: C,
61.78; H, 5.92; N, 6.86%).
(2S,4R)-2-Ferrocenyl-3-pivaloyl-4-methyl-4-(2-naphthyl-
methyl)-1,3-oxazolidin-5-one 7f. Starting with 2.97 g of the
oxazolidinone 5 and following the general alkylation procedure
General hydrolysis procedure to form the free á-methyl-á-amino
acids 8a–h
A glass column was filled with distilled water, Amberlyst-15
J. Chem. Soc., Perkin Trans. 1, 1998
261