M.C. Holland et al. / Journal of Molecular Catalysis A: Chemical 396 (2015) 335–345
337
ESI) were measured by the MS service of the Organisch-Chemisches
2.2.2. (5S)-2,2,3-Trimethyl-5-(2,4,6-trifluorobenzyl)-4-
Institut, Westfälische Wilhelms-Universität Münster.
imidazolidinone (12)
[˛]D23: −32.2 (c = 0.48, CH3OH); 1H NMR (300 MHz, CDCl3):
ı = 6.60 (2H, dd, J = 8.8, 7.7, H C4ꢀ), 3.69 (1H, dd, J = 10.2, 4.1,
2.1. Materials
H
C5), 3.22 (1H, dd, J = 14.1, 4.2, H C1ꢀ), 2.75 (3H, s, H C7), 2.68
(1H, dd, J = 14.1, 10.4, H C1ꢀ), 1.74 (1H, b, H N), 1.35 (3H, s,
The following compounds were purchased: Cinchonidine,
CD (1, Sigma-Aldrich, 96%), dihydro-4,4-dimethyl-2,3-furandione,
KPL (2, Sigma-Aldrich, 97%), methyl benzoylformate, MBF
(4, Sigma-Aldrich, 98%), 2,2,2-trifluoroacetophenone, TFAP (5,
Sigma-Aldrich, 99%), (2S,5S)-(−)-5-benzyl-3-methyl-2-(5-methyl-
2-furyl)-4-imidazolidinone (27, Sigma-Aldrich, 95%), l-proline (36,
AppliChem, >99%), (S)-(−)-indoline-2-carboxylic acid (37, Acros,
98%). The 5 wt% Pt/Al2O3 catalyst (BASF-Engelhard 4759) was pre-
reduced in a fixed-bed tubular reactor under flowing hydrogen for
1 h at 673 K, subsequently cooled down to RT for 30 min under flow-
ing hydrogen and kept under flowing nitrogen before transfer to
the autoclave. The characteristics for the as-prepared catalyst are
a platinum dispersion of 0.22 and a mean platinum particle size of
4.5 nm.
H
C6), and 1.23 (3H, s, H C6) ppm; 13C NMR (101 MHz, CDCl3):
1
3
3
ı = 172.9 (C4), 161.7 (2C, ddd, JCF = 247.7, JCF = 14.8, JCF = 11.6,
1
3
2
C3ꢀ), 161.4 (dt, JCF = 248.0, JCF = 15.7, C5ꢀ), 110.3 (td, JCF = 20.5,
4JCF = 4.7, C2ꢀ), 100.1 (2C, ddd, JCF = 28.7, JCF = 25.5, JCF = 2.1,
C4ꢀ), 75.7 (C2), 58.0 (C5), 27.6 (C6), 25.8 (C8), 25.3 (C6), and
25.3 (C7) ppm; 19F NMR (75 MHz, CDCl3): ı = −110.35 (1F, t,
2
2
4
3JFF = 5.7, F C5ꢀ), and −111.45 (2F, d, JFF = 5.7, F C3ꢀ) ppm; IR
3
(ATR): v˜ = 3326w, 2976w, 1687s, 1641m, 1622m, 1605s, 1497m,
1440s, 1400m, 1268w, 1167m, 1149w, 1116s, 1058m, 998m, 940w,
839m, and 737w cm−1; HR-ESI-MS: m/z: 273.1207 ([M + H]+, calcd
for C13H16F3N2O+: 273.1209).
The synthesis of the following compounds has been described
in the literature: 6 [11], 11 [12], 18 [13], 19 [14], 20–21 [15], 22
[16], 23–24 [17], 25–26 [18], 29–31 [19], and 32–35 [20].
Compounds 9, 12, 14, and 16 were prepared according to liter-
ature procedures [21].
2.2.3. (5S)-2,2,3-Trimethyl-5-(pentafluorobenzyl)-4-
imidazolidinone (14)
M.p. = 73.0–75.3 ◦C; [˛]D20 = −31.5 (c = 0.91 in CH3OH); 1H NMR
(300 MHz, CDCl3): ı = 3.78 (1H, dd, J = 10.3, 4.6, H C5), 3.31 (1H,
d, J = 14.1, H C1ꢀ), 2.86–2.75 (4H, m, H C1ꢀ, H C7), 1.72 (2H, b,
H
N), 1.40 (3H, s, H C6), and 1.30 (3H, s, H C6) ppm; 13C NMR
(101 MHz, CDCl3, racemic compound): ı = 172.3 (C4), 145.6 (2C,
1
1
dm, JCF = 245.6, CAr), 139.6 (dm, JCF = 245.0, C5ꢀ), 137.4 (2C, dm,
1JCF = 251.8, CAr), 111.9 (td, 2JCF = 18.4 3JCF = 3.8, C2ꢀ), 76.0 (C2), 57.7
(C5), 28.0 (C6), 26.6 (C1ꢀ), 25.6 (C6), and 25.4 (C7) ppm; 19F NMR
(282 MHz, CDCl3): ı = (−142.3)–(−142.7) (2F, m, F C3ꢀ), −157.2
(1F, t, JFF = 20.8, F C5ꢀ), and −163.0 (2F, td, JFF = 22.6, JFF = 8.3,
3
3
4
F
C4ꢀ) ppm; IR (ATR): v˜ = 3318m, 2982w, 1676s, 1519s, 1499s,
2.2.1. (5S)-2,2,3-Trimethyl-5-(3,4,5-trimethoxybenzyl)-
1441m, 1404s, 1384m, 1371m, 1303w, 1279w, 1202w, 1182m,
1156w, 1119s, 1099m, 1042m, 1012m, 977m, 964s, 937s, 885w,
795w, 768w, 736w, and 681w cm−1; HR-EI-MS: m/z: 309.1018
([M + H]+, calcd for C13H14F5N2O+: 309.1021); elemental analysis
(racemic compound) calcd (%) for C13H13F5N2O (308.2): C 50.65, H
4.25, N 9.09, F 30.82; found: C 50.74, H 4.43, N 8.87, F 31.06.
imidazolidin-4-one (9)
Rf = 0.73 (CH2Cl2/MeOH 10:1); M.p. = 116.8–118.2 ◦C; [˛]D
:
20
−37.2 (c = 0.94, CH3OH); 1H NMR (300 MHz, CDCl3): ı = 6.44 (2H,
s, H C3ꢀ), 3.81 (6H, s, H C6ꢀ), 3.80 (3H, s, H C7ꢀ), 3.75 (1H, t, J = 5.3,
H
C5), 3.02 (2H, d, J = 5.3, H C1ꢀ), 2.74 (3H, s, H C7), 1.26 (3H,
s, H C6), and 1.16 (3H, s, H C6) ppm; 13C NMR (75 MHz, CDCl3):
ı = 173.5 (C4), 153.3 (2C, C4ꢀ), 136.9 (C2ꢀ), 132.8 (C5ꢀ), 106.5 (2C,
C3ꢀ), 75.7 (C2), 61.0 (C7ꢀ), 59.4 (C5), 56.2 (2C, C6ꢀ), 37.4 (C1ꢀ), 27.3
(C6), 25.4 (C6), and 25.4 (C7) ppm; IR (ATR): v˜ = 3291w, 2920w,
2686w, 2565w, 2432w, 1702s, 1673w, 1590m, 1508w, 1459m,
1424s, 1396s, 1385m, 1328m, 1315w, 1234m, 1154w, 1113s,
1064w, 1000m, 967w, 875w, 831w, 789w, and 771w cm−1; HR-ESI-
MS: m/z: 309.1814 ([M + H]+, calcd for C16H25N2O4+: 309.1809);
elemental analysis calcd (%, racemic compound) for C16H24N2O4
(308.2): C 62.32, H 7.84, N 9.08, O 20.75; found: C 62.02, H 7.68, N
8.96, O 20.82.
2.2.4. (5S)-2,2,3-Trimethyl-5-(anthracen-3-ylmethyl)-
imidazolidin-4-one (16)
M.p. = 54.5–55.3 ◦C; [˛]D23: +23.8 (c = 0.59, CH3OH); 1H NMR
(300 MHz, CDCl3): ı = 8.45 (2H, d, J = 8.9, H C4ꢀ), 8.38 (1H, s, H C9ꢀ),
8.01 (2H, d, J = 8.0, H C7ꢀ), 7.55–7.44 (4H, m, H C5ꢀ, H C6ꢀ), 4.33
(1H, dd, J = 14.6, 3.1, H C5), 4.10 (1H, dd, J = 9.6, 3.1, H C1ꢀ),
3.81 (1H, dd, J = 14.6, 9.7, H C1ꢀ), 2.86 (3H, s, H C7), 1.36 (3H, s,
H
C6), and 1.16 (3H, s, H C6) ppm; 13C NMR (101 MHz, CDCl3):
ı = 173.4 (C4), 134.2 (2C, C2ꢀ), 131.7 (2C, C8ꢀ), 130.4 (2C, C3ꢀ),
129.3 (2C, 74ꢀ), 126.7 (C9ꢀ), 125.9 (2C, C5ꢀ or C6ꢀ), 125.1 (2C, C5ꢀ