M. P. Doyle, A. J. Catino / Tetrahedron: Asymmetry 14 (2003) 925–928
927
3. Experimental
3.3.2. Procedure B. To a solution of 1,6-heptadien-4-ol
(259 mg, 2.31 mmol) in 20 mL of anhydrous THF
7
3
.1. General
under argon at 40°C was added [1,3-bis-(2,4,6-
trimethylphenyl)-2-imidazolidinylidene)dichloro(phenyl-
methylene)-(tricyclohexylphosphine)ruthenium] (30 mg,
0.035 mmol). The resulting brown solution was stirred
for 30 min (reaction completion shown by tlc). The
solution was then allowed to cool to rt and air was
bubbled through the solution for 1 h to oxidize the
catalyst. To this solution was added triethylamine
(0.024 g, 0.231 mmol), a catalytic amount of DMAP
(ꢀ2 mg), and diketene (0.224 g, 2.66 mmol); stirring
was continued for 8 h. Evaporation of the solvent,
followed by purification by flash chromatography on
silica gel (6:1 hexanes:EtOAc), gave a clear liquid (0.334
g, 88%). Data consistent with Procedure A.
1
13
H NMR (300 MHz) and C NMR (75 MHz) spectra
were obtained as solutions in CDCl ; chemical shifts
are reported in parts per million (ppm, l) downfield
from Me Si (TMS). Mass spectra were obtained using
electron ionization on
3
4
a quadrupole instrument.
Infrared spectra were recorded using NaCl plates with
−
1
absorptions recorded in wavenumbers (cm ). Enan-
tiomeric excess (% ee) was measured with a Chiraldex
B-DM column programmed initially at 85°C for 10 min
then 1°C/min to 140°C. All reagents were commercially
obtained unless otherwise noted. Chromatographic
purification was performed using silica gel. Anhydrous
THF was distilled over Na/benzophenone ketyl, and
CH Cl was distilled over CaH prior to use. Methane-
sulfonyl azide was prepared by reaction with methane-
sulfonyl chloride with sodium azide and was not
distilled. The preparation of enantiomeric forms of
Rh (MEPY) , Rh (MEOX) , Rh (MEAZ) , and
Rh (MPPIM) have been previously reported.
2
2
2
3
.4. 1-Cyclopentene-4-yl diazoacetoacetate, 10
To a solution of 1-cyclopentene-4-yl acetoacetate 9
0.600 g, 3.57 mmol) and triethylamine (404 mg, 3.93
1
6
(
1
7
18
19
2
4
2
4
2
4
mmol) in 4 mL of anhydrous THF was added methane-
sulfonyl azide (475 mg, 3.93 mmol) in 8 mL of THF.
The reaction was stirred for 8 h at rt. Evaporation of
the solvent and purification by chromatography on
silica gel (6:1 hexanes:EtOAc) gave a light yellow oil
2
0
4
4
3
.2. 1,6-Heptadien-4-yl acetoacetate, 8
To a stirred solution of 1,6-heptadien-4-ol 7 (1.73 g,
5.4 mmol), triethylamine (0.156 g, 1.54 mmol) and a
which slowly solidified on standing (0.566 g, 80%): TLC
1
1
R =0.32 (6:1 hexanes:EtOAc); mp=44–46°C; H NMR
f
catalytic amount of DMAP (ꢀ2 mg) in anhydrous
THF (15 mL) at rt was added a solution of diketene
(
CDCl , 300 MHz) l 5.69 (s, 2H), 5.48 (tt, J=6.9, 2.4
3
Hz, 1H), 2,77 (dd, J=16.8, 6.9 Hz, 2H), 2.46–2.40
(
1.48 g, 17.7 mmol) in THF (30 mL) via addition
13
(
comp, 4H); C NMR (CDCl , 100 MHz) l 190.2,
3
funnel. The resulting solution was stirred for 8 h after
which the solvent was evaporated. The residue was
dissolved in CH Cl (50 mL), filtered through a pad of
1
2
61.3, 128.1, 75.7, 39.7, 28.2; IR (thin film) w 3068,
−1
919, 2833, 2141 (CꢁN ), 1709, 1654, 1363, 1314 cm ;
2
2
2
HRMS (EI) calcd for C H N O 195.0770, found
9
11
2
3
SiO , and evaporated to give a clear yellow liquid which
was distilled (78°C, 0.5 Torr) yielding a clear liquid
2
+
1
95.0777 (M+H) .
1
(
2.94 g, 97%): TLC R =0.42 (5:1 hexanes:EtOAc); H
f
NMR (CDCl , 300 MHz) l 5.76–5.62 (comp, 2H),
3.5. 1-Cyclopentene-4-yl diazoacetate, 6
3
5
5
1
.06–4.91 (comp, 4H), 3.36 (s, 2H), 2.32–2.23 (comp,
13
H), 2.19 (s, 3H); C NMR (CDCl , 75 MHz) l 200.3,
3
3
.5.1. Procedure A. To a solution 1-cyclopentene-4-yl
66.5, 133.1, 118.0, 73.5, 50.2, 37.8, 30.0; HRMS (EI)
diazoacetoacetate 10 (0.400 g, 2.06 mmol) in 2 mL of
+
calcd for C H O 197.1178, found 197.1176 (M+H) .
1
1
17
3
THF was added LiOH in H O (8.24 mL, 1 M). The
2
reaction was stirred for 1 h at rt, diluted with EtOAc
3
3
.3. 1-Cyclopentene-4-yl acetoacetate, 9
(
50 mL), and extracted with H O (50 mL) and brine (50
2
mL). Evaporation of the EtOAc and purification by
.3.1. Procedure A. To a solution of 1,6-heptadien-4-yl
acetoacetate 8 (686 mg, 3.50 mmol) in 35 mL of anhy-
chromatography on silica gel (9:1 hexanes:EtOAc) gave
a bright yellow liquid (0.251 g, 79%): TLC R =0.31
f
drous CH Cl under argon was added benzylidine(bis-
2
2
1
(
9:1 hexanes:EtOAc); H NMR (CDCl , 300 MHz) l
3
tricyclohexylphosphine)ruthenium(II) dichloride (29
mg, 0.035 mmol). The resulting brown solution was
stirred for 30 min (reaction complete as shown by tlc).
Air was then bubbled through the solution for 3 h to
oxidize the catalyst. Evaporation of the solvent, purifi-
cation by flash chromatography on silica gel (6:1 hex-
anes:EtOAc), followed by distillation to remove trace
5
1
2
1
2
.62 (s, 2H), 5.36 (tt, J=6.9, 2.1 Hz, 1H), 4.67 (br s,
H), 2,77 (dd, J=16.5, 6.9 Hz, 2H), 2.33 (dd, J=16.5,
13
.1 Hz, 2H); C NMR (CDCl , 100 MHz) l 166.5,
3
28.0, 74.5, 46.1, 39.5; IR (thin film) w 3111, 2944, 2907,
−
1
839, 2123 (CꢁN ), 1691, 1387 cm ; HRMS (EI) calcd
2
+
for C H N O 151.0508, found 151.0512 (M−H) .
7
7
2
2
catalyst (82°C, 0.5 Torr) gave a clear liquid (0.537 g,
1
9
1%): TLC R =0.30 (6:1 hexanes:EtOAc); H NMR
3.5.2. Procedure B. To a solution of 1-cyclopentene-4-yl
acetoacetate 5 (340 mg, 2.02 mmol) and triethylamine
(225 mg, 2.22 mmol) in 2 mL of anhydrous THF was
added methanesulfonyl azide (269 mg, 2.22 mmol) in 2
mL of THF. The reaction was stirred for 8 h at rt. A
f
(CDCl , 300 MHz) l 5.67 (s, 2H), 5.37 (tt, J=6.9, 2.1
3
Hz, 1H), 3.37 (s, 2H), 2.70 (dd, J=16.8, 6.9 Hz, 2H),
1
3
2
.37 (dd, J=16.8, 2.1 Hz, 2H), 2.19 (s, 3H); C NMR
(
CDCl , 75 MHz) l 200.5, 166.9, 128.1, 75.2, 50.1, 39.5,
3
3
1
0.0; HRMS (EI) calcd for C H O 169.0865, found
69.0869 (M+H) .
solution of LiOH in H O (8.08 mL, 1 M) was then
added. The reaction was stirred for 1 h at rt, diluted
9
13
3
2
+