A. G. Jamieson, A. Sutherland / Tetrahedron 63 (2007) 2123–2131
2127
determined as solutions irradiating with the sodium D line
(l¼589 nm) using an AA series Automatic polarimeter.
Bis(acetonitrile)palladium(II) chloride (10 mol %) was then
added and the reaction mixture stirred for 24 h. Concentra-
tion in vacuo followed by purification by flash column chro-
matography (40% ethyl acetate/petroleum ether) gave 8a
and 8b (0.28 g, 31% over three steps) as a yellow oil, in
a ratio of 4:1. nmax/cmꢀ1 (neat): 3403 (OH, NH), 2979
(CH), 1693 (CO); 8a: dH (400 MHz, CDCl3) 1.27 (3H, d,
J 6.4 Hz, 5-H3), 1.97 (1H, br d, J 5.6 Hz, OH), 4.05 (1H,
m, 4-H), 4.38 (1H, m, 3-H), 5.39 (2H, m, 1-H2), 5.90 (1H,
m, 2-H), 7.24 (1H, br s, NH); dC (100 MHz, CDCl3) 20.0
(CH3), 58.6 (CH), 68.9 (CH), 92.7 (C), 119.6 (CH2), 131.1
(CH), 161.4 (C); 8b: dH (400 MHz, CDCl3) 1.29 (3H, d,
J 6.4 Hz, 5-H3), 2.04 (1H, br s, OH), 4.05 (1H, m, 4-H),
4.38 (1H, m, 3-H), 5.33 (2H, m, 1-H2), 5.90 (1H, m, 2-H),
7.13 (1H, br s, NH); dC (100 MHz, CDCl3) 20.0 (CH3),
58.2 (CH), 68.6 (CH), 92.7 (C), 117.4 (CH2), 134.7 (CH),
162.0 (C); found (CI): MH+, 247.9825, C7H10O2N35Cl237Cl
requires MH+, 247.9826.
[a]D values are given in units 10ꢀ1 deg cm2 gꢀ1
.
4.1.1. Ethyl (2S)-(tert-butyldimethylsilyloxy)propa-
noate.21 [a]2D0 ꢀ31.1 (c 1.0, CHCl3) (lit.21 [a]D20 ꢀ28.2
(c 0.62, CHCl3); dH (400 MHz, CDCl3) 0.00 (3H, s, SiCH3),
0.03 (3H, s, SiCH3), 0.89 (9H, s, Si(CH3)3), 1.26 (3H, t,
J 7.2 Hz, OCH2CH3), 1.38 (3H, d, J 6.8 Hz, 3-H3), 4.16 (2H,
m, OCH2CH3), 4.30 (1H, q, J 6.8 Hz, 2-H); dC (100 MHz,
CDCl3) ꢀ5.0 (CH3), ꢀ4.7 (CH3), 14.5 (CH3), 18.6 (C),
21.6 (CH3), 26.0 (CH3), 60.9 (CH2), 68.7 (CH), 174.3 (C).
4.1.2. (2S)-tert-Butyldimethylsilyloxypropan-1-ol (4).22
[a]D23 +27.8 (c 1.0, CHCl3) (lit.22 enantiomer, [a]2D5 ꢀ23.1
(c 1.2, CHCl3)); dH (400 MHz, CDCl3) 0.11 (6H, s,
Si(CH3)2), 0.92 (9H, s, Si(CH3)3), 1.14 (3H, d, J 6.4 Hz,
3-H3), 1.94 (1H, dd, J 7.6, 5.0 Hz, OH), 3.39 (1H, ddd, J
11.2, 6.8, 5.0 Hz, 1-HH), 3.52 (1H, ddd, J 11.2, 7.6,
3.6 Hz, 1-HH), 3.94 (1H, m, 2-H); dC (100 MHz, CDCl3)
ꢀ4.8 (CH3), ꢀ4.4 (CH3), 18.1 (C), 19.8 (CH3), 25.8
(CH3), 68.2 (CH2), 69.1 (CH).
4.1.6. Ethyl (2S)-2-(propyloxy-2-ene)propanoate.25 [a]D25
ꢀ67.8 (c 2.0, MeOH) (lit.25 [a]D25 ꢀ70.7 (c 2.7, MeOH));
dH (400 MHz, CDCl3) 1.31 (3H, t, J 7.2 Hz, OCH2CH3),
1.44 (3H, d, J 6.8 Hz, 3-H3), 3.96 (1H, ddt, J 12.8, 6.8,
1.2 Hz, OCHHCHCH2), 4.02 (1H, q, J 6.8 Hz, 2-H), 4.16
(1H, ddt, J 12.8, 5.6, 1.2 Hz, OCHHCHCH2), 4.23 (2H, m,
OCH2CH3), 5.20–5.34 (2H, m, OCH2CHCH2), 5.89–5.99
(1H, m, OCH2CHCH2); dC (100 MHz, CDCl3) 14.3 (CH3),
18.7 (CH3), 60.8 (CH2), 71.1 (CH2), 74.1 (CH), 117.7
(CH2), 134.2 (CH), 173.3 (C).
4.1.3. Ethyl (2E,4S)-4-(tert-butyldimethylsilyloxy)pent-
2-enoate (5).23 [a]2D1 +4.4 (c 1.0, CHCl3) (lit.23 [a]2D2 +4.4
(c 1.2, CHCl3)); dH (400 MHz, CDCl3) 0.08 (3H, s, SiCH3),
0.09 (3H, s, SiCH3), 0.93 (9H, s, Si(CH3)3), 1.28 (3H, d,
J 6.4 Hz, 5-H3), 1.31 (3H, t, J 7.2 Hz, OCH2CH3), 4.21
(2H, m, OCH2CH3), 4.47 (1H, m, 4-H), 6.00 (1H, dd,
J 15.6, 2.0 Hz, 2-H), 6.94 (1H, dd, J 15.6, 4.0 Hz, 3-H); dC
(100 MHz, CDCl3) ꢀ4.9 (CH3), 14.3 (CH3), 18.2 (C), 23.6
(CH3), 25.8 (CH3), 60.3 (CH2), 67.7 (CH), 119.0 (CH),
151.9 (CH), 166.9 (C).
4.1.7. Ethyl (2S)-2-propyloxypropanoate (11).26 [a]D25
ꢀ98.3 (neat) (lit.26 [a]D20 ꢀ100.9 (neat)); dH (400 MHz,
CDCl3) 0.95 (3H, t, J 7.2 Hz, OCH2CH2CH3), 1.31 (3H, t,
J 7.2 Hz, OCH2CH3), 1.42 (3H, d, J 6.8 Hz, 3-H3), 1.64
(2H, sex, J 7.2 Hz, OCH2CH2CH3), 3.34 (1H, dt, J 8.8,
7.2 Hz, OCHHCH2CH3), 3.54 (1H, dt, J 8.8, 7.2 Hz,
OCHHCH2CH3), 3.96 (1H, q, J 6.8 Hz, 2-H), 4.22 (2H, m,
OCH2CH3); dC (100 MHz, CDCl3) 10.5 (CH3), 14.3
(CH3), 18.7 (CH3), 23.0 (CH2), 60.7 (CH2), 72.0 (CH2),
75.0 (CH), 173.6 (C).
4.1.4. (2E,4S)-4-(tert-Butyldimethylsilyloxy)-2-penten-1-
ol (6).24 [a]D23 +5.9 (c 1.0, CHCl3) (lit.24 [a]1D9 +3.7 (c 2.9,
CHCl3)); dH (400 MHz, CDCl3) 0.08 (3H, s, SiCH3), 0.09
(3H, s, SiCH3), 0.92 (9H, s, Si(CH3)3), 1.24 (3H, d, J
6.3 Hz, 5-H3), 1.43 (1H, br s, OH), 4.16 (2H, d, J 6.0 Hz,
1-H2), 4.27 (1H, m, 4-H), 5.72–5.84 (2H, m, 2-H and
3-H); dC (100 MHz, CDCl3) ꢀ4.4 (CH3), ꢀ4.2 (CH3), 18.7
(C), 24.7 (CH3), 26.3 (CH3), 63.6 (CH2), 68.9 (CH), 127.6
(CH) and 136.8 (CH).
4.1.8. (2S)-Propyloxypropan-1-ol (12).27 [a]D24 +17.8 (c
1.0, CHCl3) (lit.27 [a]D25 +26.1 (neat)); dH (400 MHz,
CDCl3) 0.94 (3H, t, J 7.6 Hz, OCH2CH2CH3), 1.12 (3H,
d, J 6.0 Hz, 3-H3), 1.61 (2H, m, OCH2CH2CH3), 2.08 (1H,
br s, OH), 3.34 (1H, dt, J 8.8, 6.8 Hz, OCHHCH2CH3),
3.41–3.61 (4H, m, 1-H2, 2-H and OCHHCH2CH3); dC
(100 MHz, CDCl3) 10.6 (CH3), 15.9 (CH3), 23.3 (CH2),
66.4 (CH2), 70.5 (CH2), 75.7 (CH).
4.1.5. (3R,4S)-3-Trichloromethylcarbonylamino-4-hydr-
oxypenta-1-ene (8a) and (3S,4S)-3-trichloromethylcarb-
onylamino-4-hydroxypenta-1-ene (8b). (2E,4S)-4-(tert-
Butyldimethylsilyloxy)-2-penten-1-ol (0.8 g, 3.7 mmol) was
dissolved in dichloromethane (20 mL) and cooled to 0 ꢁC.
1,8-Diazabicyclo[5,4,0]undec-7-ene (0.6 mL, 4.4 mmol)
and trichloroacetonitrile (0.6 mL, 5.6 mmol) were then
added and the mixture was allowed to warm to room temper-
ature and stirred for 2 h. The reaction mixture was then
filtered through a silica plug and the filtrate was concentrated
in vacuo to give an orange liquid. The allylic trichloro-
acetimidate and tetra-n-butylammonium fluoride (TBAF)
(1 M soln in tetrahydrofuran) (6.7 mL, 6.7 mmol) in THF
(20 mL) were allowed to stir at room temperature for 24 h.
The reaction mixture was concentrated and the resulting
residue was taken up in ethyl acetate (30 mL), washed
with water (25 mL), dried (MgSO4) and concentrated in va-
cuo. The product was used without further purification. The
allylic trichloroacetimidate was dissolved in THF (10 mL).
4.1.9. Ethyl (2E,4S)-4-propyloxypent-2-enoate (13).
Methyl sulfoxide (2.6 mL, 36.6 mmol) was added to a stirred
solution of oxalyl chloride (1.6 mL, 18.3 mmol) in dichloro-
methane (50 mL) at ꢀ78 ꢁC. This mixture was stirred for
0.25 h before (2S)-propyloxypropan-1-ol (1.8 g, 15.3 mmol)
in dichloromethane (30 mL) was added. The mixture was
stirred for a further 0.25 h before triethylamine (10.6 mL,
76.3 mmol) was added. This reaction mixture was then
warmed to room temperature over 2 h. Meanwhile, a solution
of lithium chloride (0.97 g, 22.9 mmol), triethyl phosphono-
acetate (4.5 mL, 22.9 mmol) and 1,8-diazabicyclo[5,4,0]-
undec-7-ene (3.4 mL, 22.9 mmol) in acetonitrile (30 mL)
was prepared and stirred for 0.5 h at room temperature.