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J¼2.64 Hz), 7.42–7.44 (m, 2H), 7.55–7.60 (m, 2H), 7.60–
7.67 (m, 3H), 7.88–7.91 (m, 2H); 13C NMR (CDCl3,
75 MHz) d 51.3 (OCH3), 59.1 (NCH), 85.9 (CHOMe),
110.5, 111.2, 124.5, 128.9, 131.7, 139.4, 143.1, 146.2,
166.9 (C]O); MS (EI) m/z (rel intensity, %) 343 (MH+,
100), 241 (13), 184 (38), 160 (82), 141 (90), 77 (64).
1.95–2.04 (m, 1H, N(CHCH)2), 2.19–2.28 (m, 1H,
N(CHCH)2), 3.03–3.14 (m, 1H, N(CHCH)2), 3.22–3.43 (m,
3H, N(CHCH)2), 3.33 (s, 3H, OCH3), 4.11 (d, 1H, J¼
5.1 Hz, CHOCH3), 4.88 (t, 1H, J¼5.1 Hz, NHCHPh), 5.85–
5.87 (m, 1H, NH), 6.98–7.11 (m, 5H), 7.30–7.39 (m, 2H),
7.47–7.52 (m, 2H), 7.72–7.75 (m, 1H); 13C NMR (CDCl3,
75 MHz) major diastereoisomer d 23.4 (N(CHCH)2), 25.7
(N(CHCH)2), 45.7 (N(CHCH)2), 45.8 (N(CHCH)2), 53.9,
57.3, 80.9 (CHOCH3), 125.9, 127.1, 127.6, 128.2, 130.2,
138.4, 143.3, 167.5 (C]O); minor diastereoisomer d 23.3
(N(CHCH)2), 25.8 (N(CHCH)2), 45.8 (N(CHCH)2), 45.9
(N(CHCH)2), 57.3, 58.5, 82.0 (CHOCH3), 125.7, 127.2,
127.9, 128.6, 130.7, 138.2, 144.9, 167.0 (C]O); MS (EI)
m/z (rel intensity, %) 373 (MH+, 100), 245 (26).
4.5.4. cis 3-Benzyloxy-4-phenyl-1-phenylsulfonyl-azeti-
din-2-one (cis21c). Treating 426 mg (1.18 mmol) of b-lac-
tam cis16c led to 470 mg of crude product (white oil); IR
1
1807 cmꢁ1 (C]O); H NMR (CDCl3, 300 MHz) d 4.25
(AB spectra, 2H, J¼11.0 Hz, Dn¼35.7 Hz, OCH2Ph), 4.98
(d, 1H, J¼5.5 Hz), 5.24 (d, 1H, J¼5.5 Hz), 6.89–6.92 (m,
2H, Harom), 7.09–7.42 (m, 10H, Harom), 7.55–7.61 (m, 1H,
Harom), 7.68–7.71 (m, 2H, Harom); 13C NMR (CDCl3,
75 MHz) d 64.3 (CHPh), 73.0 (OCH2Ph), 82.6 (CHOBn),
127.5, 128.2, 128.3, 128.4, 128.5, 128.8, 129.1, 129.2, 131.6,
134.1, 135.5, 138.7, 163.3 (C]O); MS (EI) m/z (rel intensity,
%) 411 (M+NH+4, 100), 394 (MH+, 12), 209 (37), 91 (9).
4.6.2. (2R*,3S*,13R) 3-Benzenesulfonylamino-2-me-
thoxy-3-phenyl-N-(1-phenylethyl)propionamide (27).
Treating b-lactam cis20c (150 mg, 0.47 mmol) with (R)-1-
phenylethylamine (36 mL, 0.52 mmol) led to crude product
purified by flash chromatography (pentane/ethyl acetate
9/1); 47 mg of white oil (minor diastereoisomer) and 109 mg
of colourless oil (major diastereoisomer), 76% yield; minor
4.5.5. trans 3-Benzyloxy-4-phenyl-1-phenylsulfonyl-aze-
tidin-2-one (trans21c). Treating 123 mg (0.34 mmol) of
b-lactam trans16c led to crude product purified by flash
chromatography (pentane/ethyl acetate 8/2); 88 mg of
1
diastereoisomer IR 1743 cmꢁ1 (C]O); H NMR (CDCl3,
300 MHz), two rotamers (53/47), first rotamer d 1.40 (d,
3H, J¼6.83 Hz, NHCHCH3), 3.19 (s, 3H, OCH3), 3.89 (d,
1H, J¼4.16 Hz, CHOCH3), 4.06–4.12 (m, 1H, NHCHCH3),
4.76 (dd, 1H, J1¼4.16 Hz, J2¼7.7 Hz, NHCHPh), 5.56 (d,
1H, J¼7.7 Hz, NH), 7.06–7.44 (m, 13H), 7.60–7.63 (m,
2H); second rotamer d 1.38 (d, 3H, J¼2.83 Hz, NHCHCH3),
3.19 (s, 3H, OCH3), 3.83 (d, 1H, J¼3.96 Hz, CHOCH3),
4.06–4.12 (m, 1H, NHCHCH3), 4.73 (dd, 1H, J1¼3.96 Hz,
J2¼7.7 Hz, NHCHPh), 5.54 (d, 1H, J¼7.7 Hz, NH), 7.06–
7.44 (m, 13H), 7.60–7.63 (m, 2H); 13C NMR (CDCl3,
75 MHz) two rotamers (53/47) d 19.7 (NHCHCH3), 19.8
(NHCHCH3), 59.0, 59.1, 59.2, 59.3, 60.5 (NHCHPh), 60.8
(NHCHPh), 82.7 (CHOCH3), 82.9 (CHOCH3), 127.0,
127.1, 127.2, 127.4, 128.0, 128.1, 128.2, 128.3, 128.4,
128.5, 128.7, 128.8, 132.4, 136.6, 136.7, 140.1, 140.9,
141.2, 169.5, 169.6; MS (EI) m/z (rel intensity, %) 439
(MH+, 100), 335 (25), 239 (12), 207 (30), 178 (62), 135
(55), 105 (64); major diastereoisomer IR 1657 cmꢁ1
1
yellow oil; 66% yield; IR 1800 cmꢁ1 (C]O); H NMR
(CDCl3, 300 MHz) d 4.57 (d, 1H, J¼2.6 Hz), 4.66 (AB spec-
tra, 2H, J¼11.70 Hz, Dn¼59.1 Hz, OCH2Ph), 4.85 (d, 1H,
J¼2.6 Hz), 6.89–6.92 (m, 2H, Harom), 7.09–7.42 (m, 10H,
Harom), 7.55–7.61 (m, 1H, Harom), 7.68–7.71 (m, 2H, Harom);
13C NMR (CDCl3, 75 MHz) d 65.9 (CHPh), 73.4 (OCH2Ph),
88.6 (CHOBn), 126.7, 127.6, 128.3, 128.6, 128.7, 128.9,
129.2, 129.3, 134.3, 134.8, 135.9, 138.3, 164.0 (C]O);
MS (EI) m/z 411 (MH+) this pseudo-molecular ion is relative
to the product resulting from the nucleophilic ring opening
of the b-lactam trans21c by ammonia used in MS sampling.
4.6. General procedure for b-lactam opening with
amines
To a solution containing the b-lactam in THF (0.04 mmol/L)
was added 1.2 equiv of primary or secondary amine. Stirring
was maintained at room temperature until all the starting
material had reacted (TLC monitoring). The solvent was
removed under vacuum and the residue was suspended in
ethyl acetate. The organic layer was washed with 1 N aque-
ous HCl and with saturated aqueous NaCl, dried over
MgSO4, filtered and concentrated under vacuum. The crude
product was purified by flash chromatography or precipi-
tated in appropriate solvents’ mixture.
1
(C]O); H NMR (CDCl3, 300 MHz), two rotamers (55/
45), first rotamer d 1.14 (d, 3H, J¼6.99 Hz, NHCHCH3),
3.35 (s, 3H, OCH3), 3.77 (d, 1H, J¼3.78 Hz, CHOCH3),
4.86–4.95 (m, 2H, NHCHPh and NHCHCH3), 6.55–6.62
(m, 1H, NH), 6.95–7.04 (m, 2H), 7.09–7.45 (m, 11H),
7.59–7.71 (m, 2H); second rotamer d 1.39 (d, 3H,
J¼6.99 Hz, NHCHCH3), 3.43 (s, 3H, OCH3), 3.84 (d, 1H,
J¼3.96 Hz, CHOCH3), 4.86–4.95 (m, 2H, NHCHPh and
NHCHCH3), 6.71–6.74 (m, 1H, NH), 6.95–7.04 (m, 2H),
7.09–7.45 (m, 11H), 7.59–7.71 (m, 2H); 13C NMR (CDCl3,
75 MHz), two rotamers (55/45) d 21.3 (NHCHCH3), 21.6
(NHCHCH3), 48.1, 48.2, 56.3, 56.8, 58.6, 58.7, 82.5
(CHOCH3), 82.8 (CHOCH3), 126.0, 126.1, 127.0, 127.4,
127.5, 128.0, 128.1, 128.5, 128.7, 128.8, 128.9, 132.2,
132.3, 135.9, 136.3, 141.0, 141.1, 142.0, 142.5, 168.9,
169.0; MS (EI) m/z (rel intensity, %) 439 (MH+, 100), 335
(20), 178 (14), 135 (16). Anal. Calcd for C24H26N2O4S: C,
65.73; H, 5.98; N, 6.39; S, 7.31. Found: C, 65.31; H, 5.84;
N, 6.28; S, 7.55.
4.6.1. (2S*,3S*) 3-Benzenesulfinylamino-2-methoxy-3-
phenyl-1-(pyrrolidin-1-yl)propan-1-one (23). Treating b-
lactam trans18c (150 mg, 0.50 mmol) with pyrrolidine
(46 mL, 0.55 mmol) led to crude product purified by flash
chromatography (ethyl acetate); 120 mg of white oil (two
diastereoisomers 6/4), 65% yield; IR 1633 cmꢁ1 (C]O);
1H NMR (CDCl3, 300 MHz) major diastereoisomer d 1.39–
1.73 (m, 4H, N(CHCH)2), 3.03–3.14 (m, 1H, N(CHCH)2),
3.22–3.43 (m, 3H, N(CHCH)2), 3.44 (s, 3H, OCH3), 4.06
(d, 1H, J¼5.0 Hz, CHOCH3), 4.80 (t, 1H, J¼5.0 Hz,
NHCHPh), 6.41–6.43 (m, 1H, NH), 6.98–7.11 (m, 5H),
7.30–7.39 (m, 2H), 7.47–7.52 (m, 2H), 7.72–7.75 (m, 1H);
minor diastereoisomer d 1.39–1.73 (m, 2H, N(CHCH)2),
4.6.3. (2R*,3S*) 3-Benzenesulfonylamino-2-methoxy-
3-phenyl-1-(pyrrolidin-1-yl)propan-1-one (29). Treating