F. Palacios et al. / Tetrahedron 57 12001) 3131±3141
3139
/75 MHz, CDCl3) d 166.5, 152.3, 150.9, 140.9, 120.6,
114.4±114.9 /C-arom), 60.3, 55.8, 50.8, 21.1, 14.2; IR
/neat) 3400, 2925, 1706, 1513, 1241 cm21; MS /70 eV)
249 /M1, 81). Anal calcd for C14H19NO3: C, 67.45; H,
7.68; N, 5.62. Found: C, 67.67; H, 7.68; N, 5.60.
3.6.6. ,S)-,2)-Methyl 4-[1-phenylethyl]amino-2-penteno-
ate ,7f). Prepared from the azadiene 2f following method
20
A; 13 mg /48%) of 7f as a colorles liquid. [a]D 2135.2
/CH2Cl2, c 1.5): 1H NMR /300 MHz, CDCl3) d 7.0±7.4 /m,
3
5H), 6.69 /dd, 1H, JHH7.9, 15.7 Hz), 5.81 /d, 1H,
3JHH15.8 Hz, minor diastereoisomer), 5.70 /d, 1H,
3JHH15.7 Hz, major diastereoisomer), 3.67 /s, 3H, over-
lapping: m, 1H), 3.64 /s, 3H, minor diastereoisomer) 2.9±
3.6.2. Ethyl 4-,diphenylmethyl)amino-2-pentenoate ,7b).
Prepared from the azadiene 2a following method A; 23 mg
/68%) of 7c as a colorless liquid. H NMR /300 MHz,
1
3
3.0 /m, 1H), 1.43 /s, 1H), 1.24 /d, 3H, JHH6.6 Hz), 1.10
3
3
CDCl3) d 7.1±7.3 /m, 10H), 6.7 /dd, 1H, JHH7.7 and
/d, 3H, JHH6.6 Hz, minor diasteroisomer), 1.04 /d, 3H,
3
15.6Hz), 5.81 /d, 1H, JHH15.6Hz), 4.80 /s, 1H), 4.13
3JHH6.7 Hz, major diasteroisomer); 13C NMR /75 MHz,
CDCl3) d 166.9, 152.1, 145.2, 128.4, 128.3, 126.8, 126.5,
126.4, 120.3, 119.5 /minor diastereoisomer), 55.2, 55.0
/minor), 51.6, 51.3, 24.8, 23.9 /minor), 21.6, 20.3 /minor);
IR /neat) 3340, 1740, 1519, 1240 cm21; MS /70 eV) 233
/M1, 30). Anal calcd for C14H19NO2: C, 72.07; H, 8.21; N,
6.00. Found: C, 71.89; H, 8.14; N, 5.89.
3
3
/q, 2H, JHH7.1 Hz), 3.20 /q, 1H, JHH6.5 Hz), 1.47 /m,
1H), 1.23 /t, 3H, 3JHH7.1 Hz), 1.14 /d, 3H, 3JHH6.5 Hz);
13C NMR /75 MHz, CDCl3) d 166.5, 151.6, 143.9, 143.5,
128.5, 128.4, 127.4, 127.3, 127.2, 127.0, 126.9, 126.8,
124.7, 120.7, 64.1, 60.2, 51.7, 21.0, 14.2; IR /neat) 3323,
2979, 1699, 1447, 1189, 691 cm21; MS /70 eV) 309 /M1,
5). Anal calcd for C20H23NO2: C, 77.64; H, 7.49; N, 4.53.
Found: C, 77.92; H, 7.29; N, 4.48.
3.6.7. ,R)-,1)- and ,S)-,2)-Ethyl 3-methyl-4-[1-phenyl-
ethyl]amino-2-pentenoate ,7g). Prepared from the
b-enamino phosphine oxide 3d following method B;
3.6.3. ,R)-,1)- and ,S)-,2)-Ethyl 4-[1-phenylethyl]
amino-2-pentenoate ,7c). Prepared from the b-enamino
phosphonium salt 1d following method B; 77 mg /68%)
of 7c as a yellow oil. 1H NMR /300 MHz, CDCl3) d
major diastereoisomer /R,R) and /S,S): 7.14±7.28 /m, 5H),
1
98 mg /75%) of 7g as a yellow oil. H NMR /300 MHz,
CDCl3) d major diastereoisomer: 7.14±7.28 /m, 5H), 5.67
3
/s, 1H), 4.19 /q, JHH7.1 Hz, 2H), 3.60 /q, 1H,
3
3JHH7.0 Hz), 2.94 /q, 1H, JHH6.7 Hz), 2.07 /s, 3H),
3
3
3
6.68 /dd, 1H, JHH7.6, 15.0 Hz), 5.68 /d, 1H,
1.26/t, 3H, JHH7.1 Hz), 1.25 /d, 3H, JHH7.0 Hz),
3
3JHH15.0 Hz), 4.14 /q, 2H, JHH7.0 Hz), 3.68 /q, 1H,
1.06/d, 3H,
7.14±7.28 /m, 5H), 5.84 /s, 1H), 4.19 /q, 2H,
3JHH6.7 Hz); minor diastereoisomer:
3
3JHH6.6 Hz), 3.05 /q, 1H, JHH6.8 Hz), 1.25 /d, 3H,
3JHH6.6 Hz overlapped with t at 1.24 ppm), 1.24 /t, 3H,
3JHH7.0 Hz), 1.05 /d, 3H, 3JHH6.8 Hz); minor diastereo-
isomer /R,R) and /S,S):7.14±7.28 /m, 5H), 6.68 /dd, 1H,
3JHH7.1 Hz,), 3.70 /q, 1H, JHH6.9 Hz), 3.25 /q, 1H,
3
3JHH6.8 Hz), 2.02 /s, 3H), 1.24 /d, 3H, JHH6.9 Hz),
3
1.26/t, 3H, JHH7.1 Hz), 1.15 /d, 3H, JHH6.8 Hz); 13C
NMR /75 MHz, CDCl3) d major diastereoisomer: 166.9,
161.6, 145.4, 126.5±128.5 /C-arom), 115.8, 59.6, 58.4,
55.1, 25.0, 21.0, 14.3, 14.0; minor diastereoisomer: 166.9,
161.8, 145.4, 126.5±128.5 /C-arom), 115.7, 59.6, 58.1,
55.1, 23.0, 20.1, 14.3, 14.0; IR /KBr) 3310, 2850,
1220 cm21; MS /70 eV) 246/M 1215, 15). Anal calcd for
C16H23NO2: C, 73.53; H, 8.87; N, 5.36. Found: C, 73.67; H,
8.93; N, 5.29.
3
3
3
3JHH7.6, 15.0 Hz), 5.80 /d, 1H, JHH15.0 Hz), 4.14 /q,
2H, 3JHH7.0 Hz), 3.80 /q, 1H, 3JHH6.6 Hz), 3.22 /q, 1H,
3
3JHH6.8 Hz), 1.24 /d, 3H, JHH6.6 Hz), 1.23 /t, 3H,
3
3JHH7.0 Hz), 1.10 /d, 3H, JHH6.8 Hz); 13C NMR
/75 MHz, CDCl3) d major diastereoisomer /R,S) and
/S,R): 166.6, 151.8, 145.3, 126.5±128.5 /C-arom), 120.8,
60.3, 55.3, 51.7, 24.9, 21.7, 14.2; minor diastereoisomer
/R,R) and /S,S): 166.6, 152.2, 145.3, 126.5±128.5
/C-arom), 120.1, 60.2, 55.1, 51.7, 24.0, 20.4, 14.2; IR
/KBr) 3380, 2911, 1198 cm21; MS /70 eV) 232 /M1215,
30). Anal calcd for C15H21NO2: C, 72.84; H, 8.56; N, 5.66.
Found: C, 72.95; H, 8.63; N, 5.70.
3.6.8. ,S)-,2)-Ethyl 3-methyl-4-[1-phenylethyl]amino-2-
pentenoate ,7h). Prepared from the azadiene 5g following
method A; 19 mg /69%) of 7h as
a yellow oil
20
[a]D 2143.1 /CH2Cl2, c 0.9). Spectral data for both the
major and the minor diastereoisomer of 7h are the same as
described for the major and minor diastereoisomers of 7g.
Anal calcd for C16H23NO2: C, 73.49; H, 8.89; N, 5.61.
Found: C, 73.38; H, 8.95; N, 5.68.
3.6.4. ,R)-,1)-Ethyl 4-[phenylethyl]amino-2-pentenoate
,7d). Prepared from either the b-enamino phosphonium
salt 1e following method B; 85 mg /75%),
20
[a]D 1116.9 /CH2Cl2, c 1.5, for the obtained mixture)
20
or from the azadiene 2e /81%), [a]D 1144.3 /CH2Cl2, c
0.7, for the obtained mixture). Spectral data of the major and
minor diastereoisomers obtained are the same as described
for the /R,R) and /R,S) diastereoisomers of 7c. Anal calcd
for C15H21NO2: C, 72.84; H, 8.56; N, 5.66. Found: C, 72.63;
H, 8.71; N, 5.82.
3.6.9. ,R)-,1)-Ethyl 3-methyl-4-[1-phenylethyl]amino-2-
pentenoate ,7i). Prepared from the azadiene 5h following
method A; 11 mg /58%) of 7i as
a yellow oil.
20
[a]D 1128.1 /CH2Cl2, c 0.9). Spectroscopical data for
both the major and the minor diastereoisomer of 7i are the
same as described for the major and minor diastereoisomers
of 7g. Anal calcd for C16H23NO2: C, 73.53; H, 8.87; N, 5.36.
Found: C, 73.29; H, 8.82; N, 5.31.
3.6.5. ,S)-,2)-Ethyl 4-[1-phenylethyl]amino-2-penteno-
ate ,7e). Prepared from the b-enamino phosphonium salt
1f following method B; 91 mg /80%) of 7e as a yellow
20
oil. [a]D 2107.8 /CH2Cl2, c 1.5, for the obtained
3.6.10. Synthesis of ethyl 4-amino-3-methylpentenoate 8.
A suspension of the allylamine 7h /1 mmol) and Pd/C /10%,
11 mg, 0.1 mmol) in EtOH /1 mL) was shaken in H2 atmo-
sphere /90 psi) for h. The resulting suspension was then
®ltered through a short column of SiO2, the residue washed
mixture. Spectral data of the major and minor diastereoi-
somers obtained are the same as described for the /S,S) and
/S,R) diastereoisomers of 7c. Anal calcd for C15H21NO2: C,
72.84; H, 8.56; N, 5.66. Found: C, 72.55; H, 8.57; N, 5.78.