V. Cmrecki et al. / Tetrahedron 66 (2010) 6550e6564
6561
ratio to be 60:40. The crude product was purified by flash column
chromatography (95% PE/EtOAc) and MPLC (98% PE/EtOAc) to yield
a 60:40 mixture of diastereoisomers (2S,3R)-15d and (2R,3R)-15d
(101.4 mg, 0.15 mmol, 89%) as a colorless solid.
9.2 Hz, CHbHaCONMe2), 1.96 (1H, dd, 2J 14.8 Hz, 3J 5.5 Hz, CHaHb
-
CONMe2), 2.01 (1H, m, CHB ), 2.69 (3H, s, NCHa3), 2.75 (3H, s,
*
NCHb3), 2.99 (6H, s, OCH3), 5.08 (1H, dqd, 3J 15.3, 6.1 Hz, 4J 1.13 Hz,
CH3CH]CH), 5.15 (1H, ddq, 3J 15.3, 6.9 Hz, 4J 1.5 Hz, CH3CH]CH),
5.29 (2H, s, 2H, CHCPh2OMe), 7.24e7.32 (20H, m, arom. CH); 13C
According to general procedure 6 alcohol (S)-2d (500 mg,
0.86 mmol, 1.0 equiv), triethyl orthopropionate (1.18 mL, 1.05 g,
5.93 mmol, 7.0 equiv), and a catalytic amount of propionic acid
NMR (CDCl3, 151 MHz) 18.1 (CH3CH), 23.4 (CHB ), 32.1
*
(CH2CONMe2), 35.4, 37.3 [(NCH3)2], 51.8 (OCH3), 77.9 (CHCPh2OMe),
83.4 (CPh2OCH3), 123.1 (CH3CH]CH), 127.2, 127.3, 127.5, 127.8,
128.6, 129.7 (arom. CH), 130.5 (CH3CH]CH), 141.0, 141.2 (arom.
Cipso), 172.6 (CONMe2); m/z (ESI, positive ion, N2) 626 (35)
[(MþH2O)þ], 603 (30) [Mþ], 346 (100) [(C22H18O4)þ].
(3.74 m
L) were heated at 135 ꢀC for 4 h. 1H and 13C NMR of the crude
product proved the diastereomeric ratio to be 77:23. The crude
product was purified by flash column chromatography (95% PE/
EtOAc) and MPLC (98% PE/EtOAc) to yield a 77:23 mixture of di-
astereoisomers (2S,3R)-15d and (2R,3R)-15d (506 mg, 0.75 mmol,
87%) as a colorless solid. Even though the MPLC separation was not
completely successful, a small amount of enriched diastereoisomer
(2S,3R)-15d was isolated. [Found: C, 76.31; H, 7.57. C43H51BO6 re-
quires C, 76.55; H, 7.62%]; Rf (85% PE/EtOAc) 0.47; nmax (liquid film):
4.4.11. (3R,4E,40R,50R)-3-[40,50-Bis(methoxydiphenylmethyl)-10,30,20-
dioxaborolan-20-yl]-N,N-dimethylhex-4-enamide ((R)-16b). Accord-
ing to general procedure 7 alcohol (R)-2b16 (200 mg, 0.37 mmol,
1.0 equiv) dissolved in abs toluene (0.75 mL) was treated with a 90%
3457 (br); 3093, 3058, 3027 (arom CeH-
(aliph. CeH- ), 1733 (C]O- ), 1598, 1577, 1494 (arom. C]C-
1374, 1330, 1279, 1231, 1188, 1148, 1076 (CeOeC), 1033, 1014, 967
n
), 2956, 2932, 2850, 2830
solution of N,N-dimethylacetamide dimethyl acetal (122 mL,111 mg,
n
n
n), 1447,
0.74 mmol, 2.0 equiv). The reaction mixture was stirred at 80 ꢀC for
22 h. 1H and 13C NMR of the crude product proved the di-
astereomeric ratio to be >99:1. The crude product was purified by
flash column chromatography (85% PE/EtOAc with a gradient to
70% PE/EtOAc) to yield (R)-16b as a yellow oil (194 mg, 0.32 mmol,
86%). [Found: C, 75.61; H, 7.02; N, 2.22. C38H42BNO5 requires C,
(CH]CH2, CeH-dout of plane), 915, 897, 839, 794, 728, 705, 665 cmꢁ1
;
1H NMR [CDCl3, 600 MHz, (2S,3R)-15d] 0.66 (3H, d, 3J 6.9 Hz,
CH3CHCO2Et), 0.85 (3H, t, 3J 7.2 Hz, CH3CH2CH2CH2CH2), 1.10 (3H, t,
3J 7.2, CO2CH2CH3), 1.13e1.27 (6H, m, CH3CH2CH2CH2CH2), 1.67 (3H,
t, 3J 9.8, CH-B
*
), 1.81 (2H, m, n-BuCH2), 2.18 (1H, qd, 3J 6.9, 9.8 Hz,
75.62; H, 7.01; N, 2.32%]; Rf (60% PE/EtOAc) 0.19; [
CHCl3); nmax (liquid film): 3083, 3063, 3022 (arom. CeH-n), 2980,
a
]
20 ꢁ91 (c 1.00,
D
CHCO2Et), 2.98 (6H, s, OCH3), 3.87 (2H, m, CO2CH2CH3), 5.06 (2H, m,
n-PeCH]CH), 5.28 (2H, s, 2H, CHCPh2OMe), 7.23e7.34 (20H, m,
arom. CH); 1H NMR [CDCl3, 600 MHz, (2R,3R)-15d] 0.71 (3H, d, 3J
6.8 Hz, CH3CHCO2Et), 0.79 (3H, t, 3J 7.2 Hz, CH3CH2CH2CH2CH2), 1.11
(3H, t, 3J 7.2, CO2CH2CH3), 1.13e1.27 (6H, m, CH3CH2CH2CH2CH2),
2937, 2915, 2855, 2820 (aliph. CeH-
1446 (arom. C]C- ), 1390, 1381, 1370, 1353, 1319, 1266, 1232, 1198,
1158, 1130, 1076 (CeOeC), 1033, 1019, 1001, 967 (CH]CH2, CeH-
dout of plane), 938, 923, 901, 857, 826, 796, 759, 733, 700 cmꢁ1 1H
NMR (CDCl3, 600 MHz) 1.50 (3H, ddd, 3J 6.0 Hz, 4J 1.3 Hz, 5J 0.8 Hz,
n), 1648 (C]O-n), 1494, 1466,
n
;
1.81 (2H, m, n-BuCH2), 1.84 (3H, t, 3J 9.4, 3J 5.3 Hz,CH-B
), 2.29 (1H,
*
qd, 3J 6.8, 5.3 Hz, CHCO2Et), 2.98 (6H, s, OCH3), 3.87 (2H, m,
CO2CH2CH3), 5.00 (1H, ddt, 3J 15.1, 9.4 Hz, 4J 1.3 Hz, n-PeCH]CH),
5.10 (1H, dt, 3J 15.1, 6.8 Hz, n-PeCH]CH), 5.30 (2H, s, 2H,
CHCPh2OMe), 7.23e7.34 (20H, m, arom. CH); 13C NMR [CDCl3,
151 MHz mixture of syn-(2S,3R)-15d and anti-(2R,3R)-15d] 13.9
(CH3CHCO2Et-anti), 14.0, 14.0 (CH3CH2CH2CH2CH2), 14.1, 14.2
(CO2CH2CH3), 16.4 (CH3CHCO2Et-syn), 22.3, 22.5, 29.1, 29.1, 31.0, 31.1
CH3CH), 1.96 (2H, m, CHbHaCONMe2, CHB
), 2.08 (1H, dd, 2J 15.8 Hz,
*
3J 11.7 Hz, CHaHbCONMe2), 2.82 (3H, s, NCHa3), 2.84 (3H, s, NCHb3),
2.98 (6H, s, 6H, OCH3), 5.01 (1H, ddq, 3J 15.3, 7.7 Hz, 4J 1.3 Hz,
CH3CH]CH), 5.06 (1H, dqd, 3J 15.3, 6.0 Hz, 4J 0.8 Hz, CH3CH]CH),
5.29 (2H, s, CHCPh2OMe), 7.24e7.35 (20H, m, arom. CH); 13C NMR
(CDCl3, 151 MHz) 18.1 (CH3CH), 24.0 (CHB ), 33.1 (CH2CONMe2),
*
35.4, 37.3 [(NCH3)2], 51.8 (OCH3), 77.9 (CHCPh2OMe), 83.4
(CPh2OCH3), 124.1 (CH3CH]CH), 127.2, 127.3, 127.5, 127.6, 128.5,
129.7 (arom. CH), 129.8 (CH3CH]CH); 141.2, 141.3 (arom. Cipso),
172.4 (CONMe2); m/z (ESI, positive ion, N2) 626 (10) [(MþH2O)þ],
604 (30) [(Mþ1)þ], 346 (100) [(C22H18O4)þ], 168 (22) [(C13H112)þ].
(CH3CH2CH2CH2CH2), 32.3 (CH-B
*
-syn), 32.6 (CH-B -anti), 32.4, 32.6
*
(n-BuCH2), 39.1 (CHCO2Et-anti), 41.1 (CHCO2Et-syn), 51.7, 53.4
(OCH3), 59.7, 59.7 (CO2CH2CH3), 77.6, 77.8 (CHCPh2OMe), 83.3, 83.4
(CPh2OCH), 127.2, 127.2, 127.3, 127.3, 127.4, 127.4, 127.7, 127.7, 127.8,
128.5, 129.6, 129.7 (arom. CH), 125.2, 132.6 (n-PeCH]CH -anti),
*
128.1, 130.6 (n-PeCH]CH-syn), 141.2, 141.3, 141.4, 141.4 (arom. Cipso),
176.0 (CO2Et -anti), 176.2 (CO2Et-syn); m/z (ESI, positive ion, N2) 692
(100) [(MþH2O)þ], 197 (6) [(CPh2OMe)þ].
4.4.12. (3S,4E,40R,50R)-3-[40,50-Bis(methoxydiphenylmethyl)-10,30,20-
dioxaborolan-20-yl]-N,N-dimethyl-5-phenylpent-4-enamide
[(S)-
16c}. According to general procedure 7 alcohol (R)-2c16 (145 mg,
0.24 mmol,1.0 equiv) dissolved in abs toluene (0.50 mL) was treated
with a 90% solution of N,N-dimethylacetamide dimethyl acetal
4.4.10. (3S,4E,40R,50R)-3-[40,50-Bis(methoxydiphenylmethyl)-10,30,20-
dioxaborolan-20-yl]-N,N-dimethylhex-4-enamide [(S)-16b]. Accord-
ing to general procedure 7 alcohol (S)-2b16 (1.00 g, 1.87 mmol,
1.0 equiv) was dissolved in abs toluene (3.60 mL) and treated with
a 90% solution of N,N-dimethylacetamide dimethyl acetal (0.61 mL,
497 mg, 3.74 mmol, 2.0 equiv). The reaction mixture was stirred at
80 ꢀC for 45 h. 1H and 13C NMR of the crude product proved the
diastereomeric ratio to be >99:1. The crude product was purified by
flash column chromatography (80% PE/EtOAc to 70% PE/EtOAc) to
yield (S)-16b as a yellowish oil (880 mg, 1.46 mmol, 78%). From the
(78.8 mL, 64.6 mg, 0.48 mmol, 2.0 equiv). The reaction mixture was
stirred at 80 ꢀC for 24 h.1H and 13C NMR of the crude product proved
the diastereomeric ratio to be >99:1. The crude product was purified
by flash column chromatography (85% PE/EtOAc) to yield product
(S)-16c as a light brown solid (99.9 mg, 0.15 mmol, 62%). From the
allylboronic ester (S)-16c
obtained.42 Rf (85% PE/EtOAc) 0.20; [
58e75 ꢀC; nmax (liquid film): 3083, 3058, 3032 (arom. CeH-
2967, 2946, 2901, 2855, 2830 (aliph. CeH- ), 2324, 2298 (OCH3,
CeH- ), 1744, 1635 (C]O- ), 1595, 1524, 1491, 1466, 1458, 1443
(arom. C]C- ), 1390, 1373, 1350, 1319, 1264, 1231, 1198, 1158, 1148,
1075 (CeOeC), 1031, 1021, 1001, 963 (CH]CH2, CeH-dout of plane),
a crystal structure analysis was
20
a]
ꢁ46 (c 1.01, CHCl3); mp
D
n
), 2980,
n
allylboronic ester (S)-16b
a
crystal structure analysis was
n
n
obtained.42 [Found: C, 75.19; H, 7.02; N, 2.23. C38H42BNO5 requires
n
20
C, 75.62; H, 7.01; N, 2.32%]; Rf (70% PE/EtOAc) 0.27; [
a
]
ꢁ100 (c
D
1.02, CHCl3); softening range 47e62 ꢀC; nmax (liquid film): 3091,
3058, 3029 (arom. CeH- ), 2980, 2958, 2937, 2915, 2857, 2825
(aliph. CeH- ), 1643 (C]O- ), 1494, 1466, 1446 (arom. C]C- ),
938, 923, 900, 887, 834, 799, 758, 735, 700 cmꢁ1 1H NMR (CDCl3,
;
n
600 MHz) 2.05 (1H, dd, 2J 14.7 Hz, 3J 7.9 Hz, CHbHaCONMe2), 2.08
(1H, dd, 2J 14.7 Hz, 3J 6.49 Hz, 1H, CHaHbCONMe2), 2.27 (1H, m,
n
n
n
1390, 1381, 1370, 1354, 1319, 1267, 1230, 1196, 1158, 1130, 1076
CHB ), 2.67 (3H, s, NCHa3), 2.76 (3H, s, NCHb3), 3.01 (6H, s, OCH3),
*
(CeOeC), 1033, 1019, 1001, 967 (CH]CH2, CeH-dout of plane), 938,
5.30 (2H, s, CHCPh2OMe), 5.94 (1H, dd, 3J 15.9, 7.2 Hz, PhCH]CH),
6.06 (1H, d, 3J 15.9 Hz, PhCH]CH), 7.09e7.39 (5H, m, arom. CH),
923, 901, 857, 826, 796, 757, 734, 705, 662 cmꢁ1 1H NMR (CDCl3,
;
600 MHz) 1.50 (3H, d, 3J 6.0 Hz, CH3CH),1.93 (1H, dd, 2J 14.8 Hz, 3J
7.25e7.39 (20H, arom. CH); 13C NMR (CDCl3, 151 MHz) 24.4 (CHB
),
*