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4.3, 0.7 Hz), 1.22 ppm (d, 1H, J=7.5 Hz); 13C NMR (100 MHz, CDCl3,
other half): d=203.3, 172.74, 156.2, 121.8, 80.9, 43.1, 34.1,
14.6 ppm; 13C NMR (100 MHz, CDCl3, other half): d=203.1, 172.67,
156.2, 121.9, 81.6, 42.6, 33.2, 13.6 ppm ; IR (film): n˜ =3092, 2969,
2937, 2867, 2832, 2723, 1745, 1721, 1163, 1105, 1023, 910,
814 cmÀ1; HRMS (ESI+): m/z calcd for [C8H10O3Na]: 177.0528; found:
177.0524, D=2.3 ppm.
d=196.9, 172.1, 170.2, 155.2, 122.6, 79.0, 75.1, 32.4, 20.6 ppm; IR
(film): n˜ =3469, 3101, 2926, 2850, 1736, 1373, 1231, 1164,
1100 cmÀ1; HRMS (ESI+): m/z calcd for [C7H10O5Na]: 221.0426;
found: 221.0424, D=0.9 ppm.
(S)-1-((S)-2-Methyl-5-oxo-2,5-dihydrofuran-2-yl)-3-oxopropan-2-yl
acetate (36a) and (R)-1-((S)-2-methyl-5-oxo-2,5-dihydrofuran-2-
yl)-3-oxopropan-2-yl acetate (36b): Rf (Et2O)=0.13; 1H NMR
(400 MHz, CDCl3, other half): d=9.46 (s, 1H), 7.36 (d, 1H, J=
5.6 Hz), 5.99 (d, 1H, J=5.6 Hz), 4.98 (dd, 1H, J=9.0, 2.9 Hz), 2.52
(dd, 1H, J=15.4, 2.9 Hz), 2.13 (dd, 1H, J=15.4, 9.0 Hz), 2.12 (s, 3H),
(S)-2-(((S)-2-Methyl-5-oxo-2,5-dihydrofuran-2-yl)methyl)pentanal
(33a): Rf (Et2O/n-Pentane 2:1)=0.41; [a]D =À53.5 (c=2.8, CHCl3);
1H NMR (400 MHz, CDCl3): d=9.52 (dd, 1H, J=1.0, 0.8 Hz), 7.25 (d,
1H, J=5.6 Hz), 5.92 (d, 1H, J=5.6 Hz), 2.33 (dd, 1H, J=14.5,
9.3 Hz), 2.24–2.15 (m, 1H), 1.83 (dd, 1H, 14.5, 1.8 Hz), 1.65–1.55 (m,
1H), 1.48 (s, 3H), 1.45–1.34 (m, 1H), 1.33 (app. sext, 2H, J=7.3 Hz),
0.90 ppm (t, 3H, J=7.3 Hz); 13C NMR (100 MHz, CDCl3): d=203.6,
172.3, 160.6, 120.5, 88.1, 46.3, 35.5, 32.0, 25.2, 19.9, 14.1 ppm; IR
(film): n˜ =3085, 2960, 2933, 2874, 2719, 1752, 1722, 1191, 1115,
952, 820 cmÀ1; HRMS (ESI+): m/z calcd for [C11H16O3Na]: 219.0997;
found: 219.0998, D=0.5 ppm.
1
1.51 ppm (s, 3H); H NMR (400 MHz, CDCl3, other half): d=9.45 (s,
1H), 7.39 (d, 1H, J=5.6 Hz), 6.05 (d, 1H, J=5.6 Hz), 4.94 (dd, 1H,
J=8.0, 4.2 Hz), 2.35 (dd, 1H, J=15.4, 4.2 Hz), 2.28 (dd, 1H, J=15.4,
8.0 Hz), 2.15 (s, 3H), 1.50 ppm (s, 3H); 13C NMR (100 MHz, CDCl3,
other half): d=197.1, 171.7, 170.3, 159.6, 121.5, 86.2, 74.1, 36.6,
25.1, 20.6 ppm; 13C NMR (100 MHz, CDCl3, other half): d=197.1,
171.6, 169.9, 159.2, 120.5, 86.7, 75.1, 36.5, 24.7, 20.6 ppm; IR (film):
n˜ =3467, 2982, 2937, 2842, 1742, 1373, 1229, 1123, 956, 825 cmÀ1
;
HRMS (ESI+): m/z calcd for [C10H12O5Na]: 235.0582; found:
235.0584, D=0.9 ppm.
(R)-2-(((S)-2-Methyl-5-oxo-2,5-dihydrofuran-2-yl)methyl)pentanal
(33b): Rf (Et2O/n-Pentane 2:1)=0.30; [a]D = +49.4 (c=0.98, CHCl3);
1H NMR (400 MHz, CDCl3): d=9.55 (d, 1H, J=2.7 Hz), 7.33 (d, 1H,
J=5.6 Hz), 6.04 (d, 1H, J=5.6 Hz), 2.41 (dd, 1H, J=14.4, 8.7 Hz),
2.38–2.29 (m, 1H), 1.67 (dd, 1H, J=14.4, 3.0 Hz), 1.64–1.55 (m, 1H),
1.44 (s, 3H), 1.44–1.36 (m, 1H), 1.36–1.23 (m, 2H), 0.90 ppm (t, 3H,
J=7.2 Hz); 13C NMR (100 MHz, CDCl3): d=203.2, 171.9, 159.9, 121.3,
88.1, 47.3, 37.0, 32.2, 24.5, 20.0, 14.1 ppm; IR (film): n˜ =3085, 2960,
(S)-2-(Benzyloxy)-3-((S)-2-methyl-5-oxo-2,5-dihydrofuran-2-yl)-
propanal (37a) and (R)-2-(benzyloxy)-3-((S)-2-methyl-5-oxo-2,5-
dihydrofuran-2-yl)propanal (37b): Major diastereomer: Rf (1:1
EtOAc/hexanes)=0.53; [a]D = +44.7 (c=0.7, CH2Cl2); 1H NMR
(400 MHz, CDCl3): d=9.61 (d, 1H, J=1.1 Hz), 7.41 (d, 1H, J=
5.6 Hz), 7.40–7.28 (m, 5H), 5.90 (d, 1H, J=5.6 Hz), 4.55 (d, 1H, J=
11.0 Hz), 4.32 (d, 1H, J=11.0 Hz), 3.68 (ddd, 1H, J=9.5, 2.4, 1.1 Hz),
2.38 (dd, 1H, J=15.1, 2.4 Hz), 2.06 (dd, 1H, J=15.1, 9.5 Hz),
1.51 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=201.3, 172.4, 161.1,
136.6, 128.8, 128.51, 128.46, 118.8, 86.6, 79.7, 73.0, 38.7, 25.6 ppm;
IR (film): n˜ =3430, 2981, 2931, 2873, 2854, 1729, 1454, 1115, 953,
820, 739 cmÀ1; HRMS (ESI+): m/z calcd for [C15H16O4Na]: 283.0946;
found: 283.0951, D=1.8 ppm. Minor diastereomer: Rf (1:1 EtOAc/
hexanes)=0.43; [a]D =À4.1 (c=1.3, 23:77 mixture of the major
and minor diastereomers, CH2Cl2); 1H NMR (400 MHz, CDCl3): d=
9.62 (d, 1H, J=1.4 Hz), 7.43 (d, 1H, J=5.7 Hz), 7.40–7.28 (m, 5H),
5.97 (d, 1H, J=5.7 Hz), 4.68 (d, 1H, J=11.4 Hz), 4.56 (d, 1H, J=
11.4 Hz), 3.87 (ddd, 1H, J=7.8, 4.3, 1.4 Hz), 2.18 (dd, 1H, J=14.8,
4.3 Hz), 2.10 (dd, 1H, J=14.7, 7.8 Hz), 1.47 ppm (s, 3H); 13C NMR
(100 MHz, CDCl3): d=201.6, 172.0, 160.7, 136.6, 128.9, 128.6, 128.5,
120.2, 87.1, 80.1, 73.0, 38.5, 24.1 ppm; IR (film): n˜ =3410, 2982,
2933, 2875, 1753, 1115, 953, 821 cmÀ1; HRMS (ESI+): m/z calcd for
[C15H16O4Na]: 283.0946; found: 283.0952, D=2.1 ppm.
2933, 2874, 2718, 1755, 1722, 1456, 1190, 1113, 952, 820 cmÀ1
;
HRMS (ESI+): m/z calcd for [C11H16O3Na]: 219.0997; found: 219.0998,
D=0.5 ppm.
(S)-2-Benzyl-3-((S)-2-methyl-5-oxo-2,5-dihydrofuran-2-yl)propa-
nal (34a): Rf (Et2O/hexanes 2:1)=0.24; [a]D =À34.2 (c=1.6, CHCl3);
1H NMR (400 MHz, CDCl3): d=9.62 (dd, 1H, J=1.2, 0.8 Hz), 7.33–
7.27 (m, 2H), 7.26–7.20 (m, 1H), 7.23 (d, 1H, J=5.6 Hz), 7.15–7.11
(m, 2H), 5.94 (d, 1H, J=5.6 Hz), 2.95 (dd, 1H, J=14.0, 7.3 Hz), 2.77
(dd, 1H, J=14.0, 7.3 Hz), 2.62 (app. dtdd, 1H, J=9.2, 7.3, 2.3,
1.2 Hz), 7.28 (dd, 1H, J=14.7, 9.2 Hz), 1.87 (dd, 1H, J=14.7, 2.3 Hz),
1.44 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=203.4, 172.3, 160.7,
137.2, 129.1, 128.9, 127.1, 120.5, 88.0, 47.8, 36.4, 35.5, 25.1 ppm; IR
(film): n˜ =3029, 2982, 2933, 2850, 2726, 1748, 1723, 1198, 1114,
952, 819, 702 cmÀ1; HRMS (ESI+): m/z calcd for [C15H16O3Na]:
267.0997; found: 267.1002, D=1.9 ppm.
(R)-2-Benzyl-3-((S)-2-methyl-5-oxo-2,5-dihydrofuran-2-yl)propa-
nal (34b): Rf (Et2O/hexanes 2:1)=0.17; [a]D = +69.4 (c=0.6, 89:11
1
mixture of 34b/34a, CHCl3); H NMR (400 MHz, CDCl3): d=9.65 (d,
1H, J=2.3 Hz), 7.33–7.20 (m, 3H), 7.15–7.09 (m, 2H), 7.05 (d, 1H,
J=5.6 Hz), 6.00 (d, 1H, J=5.6 Hz), 2.96 (dd, 1H, J=13.8, 6.5 Hz),
2.67 (dd, 1H, J=13.8, 8.3 Hz), 2.57 (tddd, 1H, J=8.3, 6.5, 3.1,
2.3 Hz), 2.42 (dd, 1H, J=14.8, 8.3 Hz), 1.68 (dd, 1H, J=14.8, 3.1 Hz),
1.40 ppm (s, 3H); 13C NMR (100 MHz, CDCl3): d=202.6, 171.8, 160.0,
137.5, 129.2, 128.9, 127.0, 121.4, 87.9, 48.7, 36.1, 36.0, 24.7 ppm; IR
(film): n˜ =3030, 2982, 2930, 2851, 1754, 1724, 1455, 1114, 951, 819,
702 cmÀ1; HRMS (ESI+): m/z calcd for [C15H16O3Na]: 267.0997;
found: 267.1003, D=2.2 ppm.
General procedure for the b-substituted acroleins
KHSO4 solution (sat. aq. containing KHSO4 (58 mol%) and water
(840 mol%) was added to a stirred solution of (2S,5S)-2,5-diphenyl-
pyrrolidine ((S,S)-12) (20 mol%) and 4-nitrobenzoic acid (20 mol%)
in CH2Cl2 at RT, and the reaction mixture was cooled to 08C. b-Sub-
stituted acrolein (500–1000 mol%) was added to the reaction mix-
ture and it was stirred at 08C for 10 min, after which the silyloxy-
furan (0.25 mmolmLÀ1, 100 mol%) was added and the reaction
mixture was stirred at 08C for the given time. After completion of
the reaction (determined by TLC), the mixture was transferred into
the flash column and purified by flash chromatography to afford
the desired products.
(S)-1-Oxo-3-((S)-5-oxo-2,5-dihydrofuran-2-yl)propan-2-yl acetate
(35a) and (R)-1-oxo-3-((S)-5-oxo-2,5-dihydrofuran-2-yl)propan-2-
1
yl acetate (35b): Rf (Et2O)=0.09; H NMR (400 MHz, CDCl3, major):
d=9.57 (s, 1H), 7.48 (dd, 1H, J=5.7, 1.5 Hz), 6.15 (dd, 1H, J=5.7,
2.0 Hz), 5.25–5.15 (m, 2H), 2.42 (ddd, 1H, J=15.0, 4.9 Hz), 2.20 (s,
(R)-3-((S)-2-Methyl-5-oxo-2,5-dihydrofuran-2-yl)butanal
and (S)-3-((S)-2-methyl-5-oxo-2,5-dihydrofuran-2-yl)butanal
(41a)
1
3H), 2.20–2.08 ppm (m, 1H); H NMR (400 MHz, CDCl3, minor): d=
9.55 (s, 1H), 7.47 (dd, 1H, J=5.7, 1.6 Hz), 6.18 (dd, 1H, J=5.7,
2.0 Hz), 5.25–5.15 (m, 2H), 2.21 (s, 3H), 2.27–2.08 ppm (m, 2H);
13C NMR (100 MHz, CDCl3, major): d=197.4, 172.0, 170.2, 155.1,
122.3, 79.3, 74.5, 32.8, 20.7 ppm; 13C NMR (100 MHz, CDCl3, minor):
(41b): Rf (EtOAc/hexanes 1:1)=0.46; [a]D = +48.6 (c=1.4, CHCl3);
1H NMR (250 MHz, CDCl3, major (R,S)-diastereomer): d=9.73 (dd,
1H, J=1.9, 0.9 Hz), 7.37 (d, 1H, J=5.7 Hz), 6.08 (d, 1H, J=5.7 Hz),
2.64–2.50 (m, 2H), 2.29–2.16 (m, 1H), 1.47 (s, 3H), 0.99 ppm (d, 3H,
Chem. Eur. J. 2014, 20, 1 – 12
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ꢂ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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