Total syntheses of sterically locked phycocyanobilin derivatives bearing a 15Z-anti or a 15E-anti CD-ring component

Article abstract of DOI:10.1246/bcsj.20100168

Total syntheses of sterically locked phycocyanobilin derivatives with a 15Z-anti or a 15E-anti CD-ring component were performed toward elucidation of the stereochemistry and function of the chromophore in phytochromes. In the course of the construction of a sterically locked 15E-anti CD-ring component employing 5-tosylpyrrolin-2-one derivatives as the D-ring, the Ts group was found to be rearranged under acidic conditions to give a mixture of regioisomers, both of which could be transformed into the same CD-ring precursor via detosylation with a base followed by Wittig-like coupling reaction. In addition, a sterically locked 15E-anti biliverdin derivative was also synthesized.

Full text of DOI:10.1246/bcsj.20100168

© 2010 The Chemical Society of Japan
Bull. Chem. Soc. Jpn. Vol. 83, No. 11, 1309–1322 (2010) 1309
BCSJ Award Article
Total Syntheses of Sterically Locked Phycocyanobilin Derivatives
Bearing a 15Z-anti or a 15E-anti CD-Ring Component
Kaori Nishiyama, Ayumi Kamiya, Mostafa A. S. Hammam, Hideki Kinoshita,
Shuhei Fujinami, Yutaka Ukaji,* and Katsuhiko Inomata*
Division of Material Sciences, Graduate School of Natural Science and Technology,
Kanazawa University, Kakuma, Kanazawa 920-1192
Received June 24, 2010; E-mail: inomata@se.kanazawa-u.ac.jp
Total syntheses of sterically locked phycocyanobilin derivatives with a 15Z-anti or a 15E-anti CD-ring component
were performed toward elucidation of the stereochemistry and function of the chromophore in phytochromes. In the
course of the construction of a sterically locked 15E-anti CD-ring component employing 5-tosylpyrrolin-2-one
derivatives as the D-ring, the Ts group was found to be rearranged under acidic conditions to give a mixture of
regioisomers, both of which could be transformed into the same CD-ring precursor via detosylation with a base followed
by Wittig-like coupling reaction. In addition, a sterically locked 15E-anti biliverdin derivative was also synthesized.
Phytochromes, one of the best-characterized photoreceptors
in plants, are a widespread family of red/far-red light responsive
photoreceptors first discovered in plants1 and have been recently
also discovered in bacteria,2 fungi,3 and slime molds.4 They play
critical roles in various light-regulated processes, ranging from
phototaxis and pigmentation in bacteria to seed germination,
chloroplast development, shade avoidance, and flowering in
higher plants. All phytochromes have a covalently attached
linear tetrapyrrole (bilin) chromophore that absorbs light in the
red and far-red region.5 Three different bilins are used as
chromophores: land plants use phytochromobilin (P¯B),6 and
cyanobacteria use phycocyanobilin (PCB),7 which is also a
chromophore of the light-harvesting pigment, phycocyanin, and
differs from P¯B only by substitution of the vinyl group at the
C18 position with an ethyl group.6,7b,8 The P¯B and PCB
chromophores bind covalently to the apoprotein by a thioether
bond through the A-ring ethylidene side chain. Some bacterial
phytochromes carry biliverdin (BV) as a natural chromophore
(Figure 1).3,9 We found that the BV covalently binds to the
apoprotein of Agrobacterium phytochrome Agp1 via its A-ring
vinyl side chain,10 which was recently confirmed by X-ray
crystallographic analysis of other bacteriophytochromes.11
The interchange between the physiologically inactive red
light absorbing Pr-form and the active far-red light absorbing
Pfr-form is the most essential for the light absorbing and
biological processes in the phytochrome chromophore function
(Figure 1). It is commonly accepted that the first step in the
photoconversion from Pr to Pfr is a Z to E isomerization around
the C15=C16 double bond between the C- and D-rings of the
bilin chromophores.12
In order to analyze the structure and function of the
chromophores in the reconstituted phytochromes, we have
synthesized P¯B, PCB, the modified PCBs, and BVs, in free
acid forms by developing efficient methods for the prepa-
ration of each pyrrole ring, a new coupling reaction between
them, and palladium-catalyzed deprotection of allyl pro-
panoate side chains of the B- and C-rings under mild
conditions.13 Furthermore, we have succeeded for the first
time in synthesizing the sterically locked 15Z-syn, 15Z-anti,
15E-syn, and 15E-anti BV derivatives,14,15 which made it
possible to directly confirm the stereochemistry around the
C15 position of the chromophores in Agrobacterium phyto-
chromes Agp1 and Agp2.16 Doubly locked BV derivatives
were also recently synthesized to assemble with Agp1 and
Agp2.17 Assembly experiments of the synthesized chromo-
phores with phytochrome apoproteins in vitro and in vivo
have provided us insights into the structure and function of
phytochromes, in particular the stereochemistry at the C15
position of the BV chromophore in Pr- and Pfr-forms of
Agp1 and Agp2 was determined to be 15Z-anti and 15E-
anti, respectively.13
Recently it was reported that light-induced rotation of the
A-ring but not the D-ring is the primary motion of the
chromophore during photoconversion from Pr to Pfr in the
cyanobacterial phytochrome from Synechococcus OSB¤, which
has PCB as a chromophore.18 In order to reveal the exact
mechanism of photoconversion in the cyanobacterial phyto-
chrome, the syntheses of sterically locked PCB derivatives are
crucial. In this paper, we first describe a total synthesis of 15Z-
anti PCB derivative, in which the stereochemistry between the
Published on the web October 30, 2010; doi:10.1246/bcsj.20100168

1310 Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) BCSJ AWARD ARTICLE
Me
Me
S
Protein
S
?
Protein
Me
O
O
Me
16
A
A
O
Me
Zs
NH
HN
HN
Za
Ea
16
15
D
D
5
5
O
N
ca. 660 nm
ca. 730 nm
15
H
NH HN
NH HN
Me
Me
C
C
B
B
Me
Me
Me
O C
2
O C
2
CO
CO
2
2
Pr
R
Pfr
Me
Me
2
OO
Me
18
17
*
OO
1
Me
A
D
3
Me
A
D
NH HN
NH HN
5
15
NH
N
13
NH
N
C
B
Me
Me
7
C
B
Me
Me
8
12
10
CO H
HO C
2
2
CO H
HO C
2
2
R = Vinyl, Phytochromobilin (PΦB)
R = Ethyl, Phycocyanobilin (PCB)
Biliverdin (BV)
Figure 1.
C- and D-rings is locked in Z-configuration and anti-con-
formation, respectively, corresponding to the Pr-form of Agp1
and Agp2. Next, a total synthesis 15E-anti BV derivative,
which has been reported briefly in a preliminary communica-
tion,15 and finally, 15E-anti PCB derivative corresponding to
the Pfr-form will be described.
The retro-synthetic analyses are shown in Scheme 1. In the
synthesis of sterically locked 15Z-anti PCB derivative 1, ring
closure was carried out by the intramolecular SN2 reaction of a
nitrogen atom of the D-ring toward an alkyl halide moiety of
the C-ring to form 5 as previously described.14 On the contrary,
the intramolecular Wittig-like reaction between the tethered C-
and D-rings in 8a was designed for the synthesis of a sterically
locked E-anti CD-ring component 6, which allowed production
of 15E-anti PCB derivative 2 and 15E-anti BV derivative 3
corresponding to Pfr-form.
MeOH to give the desired locked chromophore 1 in 76% yield
in a free acid form.
Next we intended to synthesize the sterically locked 15E-
anti BV derivative 3. The CD-ring component 6 was prepared
starting from the commercially available 3,4-dihydro-2H-pyran
(13) via tetrahydropyran-2-ol (14) and 5-hydroxypentanal (15)
as shown in Scheme 4. The Henry reaction with 1-nitropropane
followed by acetylation in the presence of 4-(dimethylamino)-
pyridine (DMAP) gave a mixture of nitro diacetate compound
17 and the corresponding nitro olefin 18, which was allowed
to react with t-butyl isocyanoacetate without separation in the
presence of DBU applying Barton’s method21 to give the
pyrrole derivative 19 in 26% yield from 13 in four steps.
Iodination of the ¡-position of the pyrrole 19 with N-
iodosuccinimide (NIS) followed by oxidation utilizing
Pb(OAc)4 in toluene22 gave the pyrrolinone derivative 21 in
90% yield from 19. The ¡-acetoxy group of the pyrrolinone
derivative 21 was replaced with a Ts group using anhydrous
TsNa in 94% yield, followed by protection of the pyrrolinone-
NH using Boc2O to give 23 in 86% yield.
Hydrolysis of the acetate group in 0.5 M methanolic HCl
afforded the N-protected tosylpyrrolinone derivative 24 in 97%
yield. As described in the preliminary communication,15 the
iodination of the resulting alcohol using iodine and triphenyl-
phosphine in the presence of imidazole followed by nitration
using sodium nitrite in the presence of phloroglucinol23 gave a
tosylpyrrolinone derivative bearing a nitro group in its side
chain, which was initially considered to be 26a. However,
the spectral data of the product were not identical with the
indicated structure of 26a. The hydrolysis product first assigned
as 24a was confirmed to be a ca. 1:2 mixture of the two
Results and Discussion
The AB-ring component 4 of PCB derivative was prepared
from 9, whose preparation was previously reported during the
course of the synthesis of the 15Z-anti locked BV derivative.14
Oxidation of sulfide 9 by mCPBA and subsequent heating in
xylene gave a vinylic compound 10 (Scheme 2). The resulting
compound 10 was then reduced with aluminum amalgam19
followed by acidic isomerization to give 11 in good chemical
yield. Compound 4 generated in situ from 11 by treating with
trifluoroacetic acid (TFA) was coupled with 514 under acidic
conditions to afford the sterically locked 15Z-anti PCB diallyl
ester 12 in 54% yield (Scheme 3).20 The allyl ester groups of
12 were deprotected via a Pd(0)-catalyzed reaction using
sodium p-toluenesulfinate (TsNa) as a nucleophile in THF/

K. Nishiyama et al.
Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) 1311
D
O
Ts
N
Za
NH
D
N
H
ref. 14
O
+
OHC
C
O
NH
C
CHO
A
Cl
t
HN
CO Bu
2
D
N
Za
O
AllylO C
15
2
5
N
NH
B
AllylO C
C
2
O
A
HN
CO H
HO C
2
2
1
HN
B
O
O
A
NH
HN
D
Ea
4
CO Allyl
2
15
O
N
NH
O
B
C
NBoc
D
NH
t
D
CO Bu
2
Ea
NH
Ts
CHO
CO H
HO C
2
2
2
C
NH
C
CHO
t
CO Bu
2
O
O
AllylO C
2
AllylO C
2
6
8a
A
NH
HN
D
Ea
15
N
NH
O
B
C
A
HN
HN
B
CO H
HO C
2
2
3
CO Allyl
2
7
Scheme 1.
p
S Tol
O
O
O
O
A
A
A
A
B
HN
HN
HN
HN
HN
HN
1) mCPBA
1) Al(Hg)
TFA
HN
B
HN
B
2) heat
2) TsOH
B
t
t
t
BuO C
BuO C
BuO C
2
2
2
CO Allyl
CO Allyl
CO Allyl
CO Allyl
2
2
2
2
9
10
11
4
95% (2 steps)
89% (2 steps)
not isolated
Scheme 2.

1312 Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) BCSJ AWARD ARTICLE
O
A
O
A
HN
D
N
D
N
HN
HCO H/TFA
O
O
2
N
NH
NH
then MeOH
54%
HN
B
C
C
B
CHO
t
BuO C
2
CO R
RO C
AllylO C
2
2
2
CO Allyl
2
5
11
cat. [Pd(PPh ) ]
TsNa
in THF/MeOH
3 4
R = Allyl 12
R = H
1
76%
Scheme 3.
NO
NO
NO
2
2
2
H
O
n
OH
OAc
PrNO
Ac O
2
2
cat. DMAP
cat. KOH
HCl / H O
2
in MeOH
O
O
OH
13
14
15
16
17
18
OH
OH
OAc
OAc
NBoc
R
O
O
NH
NH
X
t
t
t
t
CO Bu
CO Bu
2
2
CO Bu
:CNCH CO Bu
Boc O
cat. DMAP
2
2
2
2
Ts
DBU
Pb(OAc)
4
in THF
26% (4 steps)
in toluene
91%
in MeCN
86%
OAc
OAc
23
OAc
NIS
in acetone
TsNa
in THF
94%
R = H 19
R = I 20
X = OAc 21
X = Ts 22
99%
O
O
O
O
NaNO
phloro-
glucinol
2
NBoc
NBoc
NBoc
CO Bu
NBoc
CO Bu
Ts
X
Ts
t
t
t
t
CO Bu
Ts
CO Bu
2
Ts
HCl
2
2
2
in MeOH
97%
in DMF
60%
X
NO
NO
2
24a
24b
26a
26b
2
(ca.1 : 2 mixture)
(ca.1 : 2 mixture)
Ph P, I
3
2
X = OH 24
imidazole
in MeCN
89%
X = I 25
Scheme 4.
isomeric alcohols 24a and 24b as follows. After conversion of
the mixture of alcohols 24 to nitro compounds 26 via
iodination, the resulting nitro compounds could be separated
into two isomers, and they gave single crystals suitable for X-
ray crystallographic analysis. The X-ray analyses revealed that
they are 5-tosylpyrrolin-2-one derivative 26a and its 3-tosyl
isomer 26b, respectively, as shown in Figure 2. This suggests
that an isomerization proceeded during the acidic hydrolysis of
the acetate 23 due to steric demand.
The separated 5-tosyl isomer of the nitro compound 26a was
allowed to react with allyl 4-oxobutanoate (27)17c to construct
the nitro alcohol side chain of the 5-tosylpyrrolin-2-one
derivative 28a according to the Henry reaction. Acetylation
of the resulting alcohol 28a followed by reaction with t-butyl
isocyanoacetate gave the dipyrrole derivative 29a in 27% yield
in three steps as shown in Scheme 5. Compound 29a was
subjected to the Vilsmeier reaction24 to afford the formylated
dipyrrole derivative 8a in 71% yield. Compound 8a was then

K. Nishiyama et al.
Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) 1313
p
p
Tol
Tol
t
O S
2
O
SO
N
Bu
2
O
t
O
Bu
t
O
O
O
Bu
N
O
O
O
O
t
Bu
NO
2
NO
2
26a
26b
Figure 2.
treated with 99% formic acid to cleave the Boc and t-butyl ester
giving a dicarboxylic acid derivative 30a, which was subjected
to our original Wittig-like coupling reaction using tri(n-butyl)-
phosphine in the presence of DBU13,25 to afford the pyrro-
methenone derivative 31 in 46% yield from 8a in two steps. In
a similar manner, the 3-tosyl isomer 26b was converted to the
formylated dipyrrole derivative 8b. The treatment of the
dipyrrole 8b with formic acid followed by tri(n-butyl)phos-
phine and DBU gave the same pyrromethenone derivative 31 in
60% yield from 8b.
Furthermore, the CD-ring 31 could be synthesized without
the separation of the isomeric nitro compounds 26a and 26b in
similar chemical yields (Scheme 6).
Finally, the acid 31 was converted to the corresponding
aldehyde 6 via decarboxylation and formylation by treating
with trimethyl orthoformate in TFA in 63% yield.
As 15E-anti locked CD-ring component 6 was in hand, the
synthesis of sterically locked 15E-anti BV derivative 3 was
then examined by coupling with the AB-ring component. The
AB-ring component 7 of BV derivative was obtained from 9 as
previously reported.14 The coupling reaction between the 15E-
anti CD- and AB-ring components (6 and 7) was carried out
under acidic conditions to afford the sterically locked BV
diallyl ester derivative 32 in 71% yield. The deprotection of the
allyl esters was achieved by Pd(0)-catalyzed reaction in the
presence of TsNa as a nucleophile to give the desired BV
derivative 3 bearing a 15E-anti CD-ring component in 70%
yield (Scheme 7).
The coupling of 6 with 4, generated in situ from 11, was
accomplished under acidic conditions to afford the 15E-anti
PCB derivative 33. Final deprotection of allyl ester furnished
the free acid 2 quantitatively (Scheme 8).
Conclusion
As described above, total syntheses of the sterically locked
15Z-anti and 15E-anti PCB derivatives 1, 2, and 15E-anti BV
derivative 3 were achieved. These sterically locked chromo-
phores will make it possible to investigate the stereochemistry
and function of phytochrome chromophores both in vitro and in
vivo.
Experimental
The 1H and 13C NMR spectra were recorded on JEOL
Lambda 400, Lambda 300, and ECS 400 NMR spectrometers.
The chemical shifts were determined in the ¤-scale relative
to TMS (¤ 0) as an internal standard. The IR spectra were
measured on a JASCO FT/IR-230 spectrometer. The MS
spectra were recorded with a JEOL SX-102A mass spectrom-
eter. THF and Et2O were freshly distilled from sodium
diphenylketyl. All other solvents were distilled and stored
over drying agents. Merck silica gel 60 PF254 (Art. 7749) was
used for thin-layer chromatography (TLC) and Cica-Merck
silica gel 60 (No. 9385-5B) and Cica silica gel 60N
(No. 37563-84) for flash column chromatography.
t-Butyl 3-(2-Allyloxycarbonylethyl)-4-methyl-5-[(4-meth-
yl-5-oxo-3-vinyl-1H-pyrrol-2(5H)-ylidene)methyl]-1H-pyr-
Finally, the synthesis of sterically locked 15E-anti PCB 2
was examined by coupling with AB-ring component of PCB.
role-2-carboxylate (10).
allyloxycarbonylethyl)-4-methyl-5-({4-methyl-5-oxo-3-[2-(p-
To a solution of t-butyl 3-(2-

1314 Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) BCSJ AWARD ARTICLE
O
NBoc
O
D
O
t
H
CO Allyl
2
CO Bu
NBoc
2
t
27
Ts
Ac O
:CNCH CO Bu
2 2
2
D
t
n
cat. DMAP
DBU
CO Bu cat. Bu NOH
2
4
Ts
NO
2
in THF
in MeCN
27%
OH
(3 steps from 26a)
NO
2
AllylO C
2
26a
28a
O
O
O
NBoc
NR'
D
NH
D
D
t
Ea
CO Bu
2
CO R
2
Ts
O=PCl
DMF
Ts
3
n
Bu P, DBU
CHO
3
NH
C
in THF/DMF
46% (from 8a)
then
NH
C
NH
CO H
C
aq. NaOAc
2
t
CO Bu
71%
2
CO R
2
AllylO C
2
AllylO C
2
AllylO C
31
29a
2
t
R = Bu
8a
n
R' = Boc
Bu P, DBU
in THF/DMF
60% (from 8b)
3
99% HCO H
2
R, R' = H 30a
O
1)
H
O
CO Allyl
O
2
27
n
NR'
cat. Bu NOH
in THF
NBoc
4
Ts
D
Ts
O
D
t
NBoc
CO R
CO Bu
2
2
Ts
D
O=PCl
DMF
2) Ac O
cat. DMAP
3
2
t
CO Bu
CHO
2
t
3) :CNCH CO Bu
then
2
2
NH
NH
C
C
DBU
in MeCN
42% (3 steps)
aq. NaOAc
82%
t
CO R
CO Bu
2
2
NO
2
AllylO C
AllylO C
2
26b
2
29b
t
R = Bu
8b
R' = Boc
99% HCO H
2
R, R' = H 30b
Scheme 5.
tolylthio)ethyl]-1H-pyrrol-2(5H)-ylidene}methyl)-1H-pyrrole-
2-carboxylate (9)14 (627 mg, 1.14 mmol) in CH2Cl2 (15 mL),
a solution of mCPBA (70% purity, 281 mg, 1.14 mmol) in
CH2Cl2 (5 mL) was added dropwise at 0 °C under a nitrogen
atmosphere, and the mixture was allowed to stir for 5 min at
0 °C. The organic solvent was removed under reduced pressure,
and the residue was partitioned between AcOEt and water. The
organic extract was washed successively with saturated
aqueous solutions of NaHSO3, NaHCO3, brine, and dried over
MgSO4. After evaporation of the solvent, the residue was
dissolved in xylene (10 mL) and the solution was refluxed with
stirring for 1 h. After removal of the solvent under reduced
pressure, the obtained solid product was recrystallized from
AcOEt/hexane to give 10. The residue obtained by evaporation
of the mother liquid was purified by flash column chromatog-
raphy (hexane/AcOEt = 3/1, v/v) to give additional 10. The
total amount of 10 was 463 mg (95% yield) as a yellow solid.
Mp 192.5-193.5 °C (from AcOEt). IR (KBr): 3350, 3124,
2979, 1730, 1686, 1656, 1449, 1366, 1275, 1159, 1130, 1056,
¹1
992, 915, 849, 765, 733, 688 cm
.
1H NMR (400 MHz,
CDCl3): ¤ 1.57 (s, 9H), 2.09 (s, 6H), 2.55 (t, 2H, J = 8.1
Hz), 3.02 (t, 2H, J = 8.1 Hz), 4.59 (d, 2H, J = 5.6 Hz), 5.21
(dd, 1H, J = 10.5, 1.3 Hz), 5.30 (dd, 1H, J = 17.1, 1.3 Hz),
5.65 (dd, 1H, J = 17.5, 1.3 Hz), 5.67 (dd, 1H, J = 11.5,
1.3 Hz), 5.91 (ddt, 1H, J = 17.1, 10.5, 5.6 Hz), 6.10 (s, 1H),
6.63 (dd, 1H, J = 17.5, 11.5 Hz). Two NH protons were not
observed clearly. Found: C, 67.68; H, 7.17; N, 6.46%. Calcd
for C24H30N2O5: C, 67.58; H, 7.09; N, 6.57%.
t-Butyl 3-(2-Allyloxycarbonylethyl)-5-{(Z)-[(E)-3-ethyl-
idene-4-methyl-5-oxopyrrolidin-2-ylidene]methyl}-4-methyl-
1H-pyrrole-2-carboxylate (11). To 10 (200 mg, 0.468 mmol)
in THF/H2O (2.6 mL/0.26 mL) was added aluminum amal-
gam,19 which was prepared from aluminum foil (64 mg,
2.37 mmol) by the successive treatment with 1 M NaOH aq,

K. Nishiyama et al.
Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) 1315
O
O
1)
H
CO Allyl
2
27
NBoc
n
cat. Bu NOH
D
O
4
t
in THF
CO Bu
NBoc
2
Ts
D
2) Ac O
2
t
CO Bu
2
cat. DMAP
O=PCl , DMF
3
Ts
26b
29b
t
NH
C
then aq. NaOAc
67%
3) :CNCH CO Bu
2
2
DBU
in MeCN
28% (3 steps)
t
CO Bu
2
NO
2
AllylO C
2
26a
29a
(26a : 26b = ca.1 : 2)
O
O
O
NBoc
NH
NH
D
D
D
t
CO Bu
2
(MeO) CH
/ TFA
3
Ts
1) 99% HCO H
2
CHO
NH
NH
C
8b
n
C
63%
2) Bu P, DBU
3
NH
C
CO H
CHO
2
in THF/DMF
49% (2 steps)
t
CO Bu
2
AllylO C
AllylO C
2
2
AllylO C
8a
31
2
6
Scheme 6.
O
O
O
O
A
NH
A
NH
HN
D
D
HN
H SO / MeOH
2
4
N
B
NH
HN
B
NH
71%
C
C
CHO
CO R
RO C
CO Allyl
2
AllylO C
2
2
2
6
7
cat. [Pd(PPh ) ]
3 4
R = Allyl 32
TsNa
in THF/MeOH
70%
R = H
3
Scheme 7.
O
O
O
O
R
A
NH
D
A
B
NH
D
HN
HN
HN
MeOH
67%
N
NH
NH
B
C
C
CHO
CO R
RO C
CO Allyl
2
AllylO C
2
2
2
6
cat. [Pd(PPh ) ]
t
3 4
R = Allyl 33
R = H
R = CO Bu 11
2
TsNa
in THF/MeOH
quant.
TFA
2
R' = H 4 (not isolated)
Scheme 8.

1316 Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) BCSJ AWARD ARTICLE
H2O, THF, 0.5% HgCl2 aq, H2O, THF, and the resulting
suspension was stirred for 2 h at room temperature. The
reaction mixture was filtered through a pad of Celite. The
filtrate was condensed under reduced pressure and the residue
was partitioned between AcOEt and water. The organic extract
was washed with brine and then dried over MgSO4. After
evaporation of the solvent, the residue was dissolved in CH2Cl2
(2.6 mL), and p-TsOH¢H2O (89 mg, 0.468 mmol) was added
under a nitrogen atmosphere. After stirring for 5 min at room
temperature, the solvent was removed under reduced pressure
and the residue was partitioned between AcOEt and water.
The organic extract was washed with brine and dried over
MgSO4, followed by evaporation of the solvent. The residue
was separated by TLC on SiO2 (hexane/AcOEt = 2/1, v/v) to
give 11 (178 mg, 0.416 mmol) in 89% yield as a yellow solid.
The spectral data were identical with those previously
reported.22,26
250/15/1, v/v/v). The blue fraction was evaporated and the
resulting solid residue was recrystallized from CHCl3/hexane.
Free acid 1: a blue solid, 19 mg (0.034 mmol), in 76% yield.
Mp >280 °C (from CHCl3/hexane). IR (KBr): 3213, 2926,
1778, 1694, 1599, 1454, 1395, 1277, 1159, 1064, 963, 895,
1
824 cm¹1. H NMR (C5D5N): ¤ 1.10 (t, 3H, J = 7.6 Hz), 1.38
(d, 3H, J = 7.6 Hz), 1.70 (d, 3H, J = 7.3 Hz), 2.12 (s, 3H), 2.13
(s, 3H), 2.40 (q, 2H, J = 7.6 Hz), 2.84 (t, 2H, J = 7.1 Hz),
2.87-2.92 (m, 4H), 3.14-3.20 (m, 4H), 3.17 (q, 1H, J =
7.6 Hz), 4.06-4.10 (m, 2H), 6.06 (s, 1H), 6.32 (q, 1H, J =
7.3 Hz), 6.78 (s, 1H), 7.41 (s, 1H). Two NH protons and two
COOH protons were not observed clearly. UV-vis (MeOH)
-
365 (¾ = 21100), 608 (¾ = 72000) nm. HRMS (FAB+)
max
(M+ + 1), Found: m/z 599.2881. Calcd for C34H39N4O6:
599.2870.
t-Butyl 3-(4-Acetoxybutyl)-4-ethyl-1H-pyrrole-2-carbox-
ylate (19). To a mixture of H2O (30 mL) and concd HCl
(2.5 mL), 3,4-dihydro-2H-pyran (13) (10.046 g, 0.120 mol) was
added at room temperature. After stirring for 40 min, the
mixture was neutralized with a saturated aqueous solution of
NaHCO3 and then extracted with Et2O. The organic extract was
dried over MgSO4 and the solvent was evaporated to give a
colorless oil of a mixture of tetrahydropyran-2-ol (14) and 5-
hydroxypentanal (15) (5.570 g). To the mixture of 14 and 15
(5.570 g, 0.055 mol) and 1-nitropropane (9.730 g, 0.109 mol)
was added KOH (0.616 g, 0.011 mol) in MeOH (11 mL)
dropwise at 0 °C. After stirring overnight at room temperature,
the reaction mixture was neutralized by adding 1 M HCl and
the organic solvent was removed under reduced pressure. The
residue was partitioned between AcOEt and water, and the
organic extract was successively washed with a saturated
aqueous solution of NaHCO3, brine, and dried over MgSO4.
The solvent was evaporated to give the nitro alcohol 16
(9.033 g) as a yellow oil. To a mixture of 16 (9.033 g, 0.047
mol) and DMAP (1.160 g, 9.5 mmol) in THF (10 mL), Ac2O
(9.8 mL, 0.104 mol) was added dropwise at 0 °C. After stirring
at room temperature for 3 h, the reaction mixture was quenched
by adding MeOH and the solvent was removed under reduced
pressure. The residue was partitioned between AcOEt and
water and the organic extract was successively washed with a
saturated aqueous solution of NaHCO3, brine, and dried over
Na2SO4. The solvent was evaporated to give an oil of a mixture
of 6-nitrooctane-1,5-diyl diacetate (17) and 6-nitrooct-5-enyl
acetate (18) (12.285 g). To a solution of t-butyl isocyanoacetate
(3.133 g, 22.22 mmol) in THF (10 mL), DBU (7.435 g,
48.914 mmol) was added at 0 °C under a nitrogen atmosphere,
followed by dropwise addition of the mixture of 17 and 18
(12.285 g) in THF (5 mL).21 After stirring overnight at room
temperature, the solvent was removed under reduced pressure
and the residue was partitioned between AcOEt and water. The
organic extract was successively washed with 1 M HCl, a
saturated aqueous solution of NaHCO3, brine, and then dried
over Na2SO4. The solvent was evaporated and the residue was
separated by flash column chromatography (SiO2, hexane/
AcOEt = 6/1, v/v) to give 19 (4.764 g, 26% yield in 4 steps)
as an oil. IR (neat): 3320, 2968, 2934, 2868, 2360, 2341, 1739,
Allyl 3-{2-[1-(2-Allyloxycarbonylethyl)-6-ethyl-5-methyl-
7-oxo-3,7,8,9-tetrahydro-3,7a-diazacyclopenta[f]azulen-2-yl-
methylene]-5-(3-ethylidene-4-methyl-5-oxopyrrolidin-2-yl-
idenemethyl)-4-methyl-2H-pyrrol-3-yl}propanoate (12). To
11 (13 mg, 0.030 mmol) and 514 (8 mg, 0.022 mmol) was added
HCO2H (0.14 mL) and TFA (0.07 mL) at room temperature
under a nitrogen atmosphere. After stirring for 10 min, the
resulting brown solution was condensed under reduced
pressure. To the residue was added MeOH (5.0 mL) and the
reaction mixture was stirred for 2 h. The blue reaction mixture
was quenched with a phosphate buffer solution (pH 7.0) and
extracted with AcOEt. The organic layer was washed with
brine, and then dried over Na2SO4. The solvent was evaporated
and the residue was separated by TLC on SiO2 (CHCl3/
AcOEt/EtOH = 40/8/1, v/v/v) to afford 12 (12 mg, 0.012
mmol) in 54% yield as a blue solid. Mp 113-115 °C (from
CH2Cl2/hexane). IR(KBr): 3456, 2935, 1730, 1674, 1615,
1586, 1455, 1412, 1338, 1314, 1280, 1233, 1212, 1160, 1100,
1
1040, 991, 953, 824, 771, 662 cm¹1. H NMR (CDCl3): ¤ 1.11
(t, 3H, J = 7.6 Hz), 1.45 (d, 3H, J = 7.3 Hz), 1.94 (d, 3H,
J = 7.1 Hz), 2.06 (s, 3H), 2.20 (s, 3H), 2.39 (q, 2H, J =
7.6 Hz), 2.56 (t, 2H, J = 7.3 Hz), 2.57 (t, 2H, J = 7.6 Hz),
2.87-2.89 (m, 2H), 2.91 (t, 2H, J = 7.6 Hz), 2.95 (t, 2H,
J = 7.3 Hz), 3.28 (q, 1H, J = 7.3 Hz), 3.96-4.02 (m, 2H), 4.56
(d, 2H, J = 5.9 Hz), 4.57 (d, 2H, J = 5.9 Hz), 5.20 (d, 1H,
J = 10.1 Hz), 5.21 (d, 1H, J = 10.1 Hz), 5.27 (d, 1H, J =
17.1 Hz), 5.28 (d, 1H, J = 17.1 Hz), 5.85 (s, 1H), 5.88 (ddt, 2H,
J = 17.1, 10.1, 5.9 Hz), 6.35 (s, 1H), 6.42 (q, 1H, J = 7.1 Hz),
6.64 (s, 1H). Two NH protons were not observed clearly.
HRMS (FAB+) (M+ + 1), Found: m/z 679.3485. Calcd for
C40H47N4O6: 679.3496.
3-{2-[1-(2-Carboxyethyl)-6-ethyl-5-methyl-7-oxo-3,7,8,9-
tetrahydro-3,7a-diazacyclopenta[ f]azulen-2-ylmethylene]-
5-(3-ethylidene-4-methyl-5-oxopyrrolidin-2-ylidenemethyl)-
4-methyl-2H-pyrrol-3-yl}propanoic Acid (1). To a mixed
solution of 12 (27 mg, 0.045 mmol) and [Pd(PPh3)4] (10 mg,
0.009 mmol) in THF (1.0 mL), a solution of TsNa (16 mg,
0.090 mmol) in MeOH (1.0 mL) was added under a nitrogen
atmosphere at room temperature. After stirring for 10 min, the
reaction mixture was quenched by the addition of thiourea
(3 mg, 0.036 mmol). The solution was directly separated by
flash column chromatography (SiO2, CHCl3/MeOH/AcOH =
1684, 1566, 1552, 1505, 1457, 1406, 1367, 1317, 1246, 1140,
¹1
1113, 1083, 1059, 941, 907, 840, 785, 745 cm
.
1H NMR
(CDCl3): ¤ 1.18 (t, 3H, J = 7.5 Hz), 1.54-1.74 (m, 4H), 1.57 (s,

K. Nishiyama et al.
Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) 1317
9H), 2.04 (s, 3H), 2.43 (q, 2H, J = 7.5 Hz), 2.72 (t, 2H, J =
7.9 Hz), 4.08 (t, 2H, J = 6.4 Hz), 6.65 (d, 1H, J = 2.7 Hz), 9.32
(s, 1H). HRMS (FAB+) (M+ + 1), Found: m/z 310.2018.
Calcd for C17H28NO4: 310.2038.
Di-t-butyl 3-(4-Acetoxybutyl)-4-ethyl-5-oxo-2-tosyl-1H-
pyrrole-1,2(2H,5H)-dicarboxylate (23). To a mixture of 22
(17.64 g, 42 mmol) and di-t-butyl dicarbonate (Boc2O, 13.75 g,
63 mol) in MeCN (100 mL), DMAP (1.03 g, 8.4 mmol) in
MeCN (10 mL) was added dropwise at ¹40 °C under a nitrogen
atmosphere. After stirring for 30 min at room temperature, the
solvent was removed under reduced pressure and the residue
was partitioned between AcOEt and water. The organic extract
was washed with brine and then dried over MgSO4. The
solvent was evaporated and the residue was separated by flash
column chromatography (SiO2, hexane/AcOEt = 1/1, v/v) to
give 23 (18.78 g, 86% yield) as a white solid. Mp 102-104 °C
(from Et2O/hexane). IR (KBr): 2979, 2940, 2880, 1766, 1739,
1647, 1597, 1464, 1369, 1314, 1285, 1254, 1232, 1214, 1154,
1086, 1043, 1006, 976, 950, 843, 819, 796, 778, 742, 706,
t-Butyl 3-(4-Acetoxybutyl)-4-ethyl-5-iodo-1H-pyrrole-2-
carboxylate (20). To a solution of compound 19 (3.40 g,
11 mmol) in acetone (50 mL), N-iodosuccinimide (2.97 g,
13.2 mmol) was added at room temperature under a nitrogen
atmosphere.22 After stirring for 1 h, the solvent was removed
under reduced pressure and the residue was partitioned between
AcOEt and water. The organic extract was successively washed
with saturated aqueous solutions of NaHSO3, NaHCO3, brine,
and then dried over MgSO4. The solvent was evaporated and
the residue was separated by flash column chromatography
(SiO2, hexane/AcOEt = 7/1, v/v) to give 20 (4.740 g, 99%
yield) as an oil. IR (neat): 3457, 3296, 2965, 2869, 1738, 1665,
1557, 1476, 1457, 1402, 1367, 1318, 1242, 1169, 1139, 1109,
1
661 cm¹1. H NMR (CDCl3): ¤ 0.81 (t, 3H, J = 7.5 Hz), 1.48
(s, 18H), 1.64-1.78 (m, 4H), 2.05 (s, 3H), 2.21-2.33 (m, 1H),
2.39-2.66 (m, 3H), 2.43 (s, 3H), 4.10 (t, 2H, J = 6.1 Hz), 7.29
(d, 2H, J = 8.3 Hz), 7.65 (d, 2H, J = 8.3 Hz). Found: C, 60.03;
H, 6.98; N, 2.50%. Calcd for C29H41NO9S: C, 60.08; H, 7.13;
N, 2.42%.
Di-t-butyl 4-Ethyl-3-(4-hydroxybutyl)-5-oxo-2-tosyl-1H-
pyrrole-1,2(2H,5H)-dicarboxylate (24a) and Di-t-butyl
4-Ethyl-3-(4-hydroxybutyl)-5-oxo-4-tosyl-1H-pyrrole-1,2-
1
1058, 948, 860, 846, 779 cm¹1. H NMR (CDCl3): ¤ 1.07 (t,
3H, J = 7.5 Hz), 1.56-1.75 (m, 4H), 1.57 (s, 9H), 2.06 (s, 3H),
2.40 (q, 2H, J = 7.5 Hz), 2.75 (t, 2H, J = 7.8 Hz), 4.09 (t, 2H,
J = 6.2 Hz), 9.20 (s, 1H). HRMS (FAB+) (M+ + 1), Found:
m/z 436.0985. Calcd for C17H27INO4: 436.0998.
t-Butyl 2-Acetoxy-3-(4-acetoxybutyl)-4-ethyl-5-oxo-2,5-
dihydro-1H-pyrrole-2-carboxylate (21). A mixed solution
20 (4.25 g, 9.76 mmol) and lead tetraacetate [Pb(OAc)4, 6.49 g,
14.6 mmol] in toluene (30 mL) was stirred at room temperature
for 2 d.22 The reaction mixture was filtered through a pad of
Celite and the filtrate was partitioned between AcOEt and
water. The organic extract was successively washed with
saturated aqueous solutions of NaHSO3, NaHCO3, brine, and
then dried over MgSO4. The solvent was evaporated and the
residue was separated by flash column chromatography (SiO2,
hexane/AcOEt = 4/1, v/v) to give 21 (3.405 g, 91% yield) as
(4H,5H)-dicarboxylate (24b).
To compound 23 (18.78 g,
36 mmol) was added 0.5 M methanolic HCl (229 mL) and the
solution was stirred overnight at room temperature. The
mixture was neutralized with a saturated aqueous solution of
NaHCO3 and the solvent was removed under reduced pressure.
The residue was partitioned between AcOEt and water and the
organic extract was washed with brine and then dried over
MgSO4. The solvent was evaporated and the residue was
separated by flash column chromatography (SiO2, hexane/
AcOEt = 4/1, 3/1, 2/1, 1/1, v/v) to give a ca. 1:2 mixture of
24a and 24b (16.08 g, 97% yield) as an oil. Analytical samples
of 24a and 24b were obtained by further separation of a part of
the mixture by flash column chromatography.
an oil. IR (neat): 3382, 2977, 2938, 2876, 2360, 2342, 1727,
¹1
1459, 1370, 1241, 1156, 1117, 1048, 841, 819, 782 cm
.
1H NMR (CDCl3): ¤ 1.11 (t, 3H, J = 7.5 Hz), 1.45 (s, 9H),
1.50-1.73 (m, 4H), 2.05 (s, 3H), 2.14 (s, 3H), 2.30 (q, 2H,
J = 7.5 Hz), 2.34-2.49 (m, 2H), 4.10 (t, 2H, J = 6.2 Hz), 6.77
(s, 1H). HRMS (FAB+) (M+ + 1), Found: m/z 384.2022.
Calcd for C19H30NO7: 384.2038.
24a: a white soild. Mp 87 °C (from AcOEt). IR (KBr): 3555,
2980, 2942, 2868, 1783, 1729, 1623, 1595, 1460, 1395, 1371,
1321, 1281, 1254, 1226, 1153, 1083, 1013, 960, 847, 815, 795,
1
t-Butyl 3-(4-Acetoxybutyl)-4-ethyl-5-oxo-2-tosyl-2,5-di-
hydro-1H-pyrrole-2-carboxylate (22). A mixture of com-
pound 21 (1.99 g, 5.19 mmol) and anhydrous TsNa (1.938 g,
10.89 mmol) in THF (50 mL) was refluxed for 1.5 h under a
nitrogen atmosphere. The solvent was removed under reduced
pressure and the residue was partitioned between AcOEt and
water. The organic extract was washed with brine and then
dried over MgSO4. The solvent was evaporated and the residue
was separated by flash column chromatography (SiO2, hexane/
AcOEt = 4/1, v/v) to give 22 (2.345 g, 94% yield) as an oil.
IR (neat): 3580-3200, 2978, 2940, 2880, 2360, 2340, 1728,
764, 706, 658 cm¹1. H NMR (CDCl3): ¤ 0.91 (t, 3H, J = 7.4
Hz), 1.50 (s, 9H), 1.52 (s, 9H), 1.55-1.70 (m, 5H), 2.12-2.29
(m, 2H), 2.40 (s, 3H), 2.55-2.68 (m, 1H), 2.75-2.89 (m, 1H),
3.66-3.76 (m, 2H), 7.26 (d, 2H, J = 8.3 Hz), 7.70 (d, 2H,
J = 8.3 Hz). Found: C, 60.39; H, 7.22; N, 2.66%. Calcd for
C27H39NO8S: C, 60.31; H, 7.31; N, 2.61%.
24b: an oil. IR (neat): 3559, 2980, 2936, 2877, 1791, 1730,
1628, 1597, 1458, 1393, 1369, 1322, 1254, 1211, 1152, 1084,
¹1
1006, 944, 846, 817, 795, 759, 706, 661 cm
.
1H NMR
(CDCl3): ¤ 0.81 (t, 3H, J = 7.8 Hz), 1.47 (s, 9H), 1.48 (s, 9H),
1.61-1.86 (m, 5H), 2.24-2.34 (m, 1H), 2.43 (s, 3H), 2.46-2.52
(m, 3H), 3.68-3.75 (m, 2H), 7.30 (d, 2H, J = 8.2 Hz), 7.66
(d, 2H, J = 8.2 Hz). HRMS (FAB+) (M+ + 1), Found: m/z
538.2469. Calcd for C27H40NO8S: 538.2474.
Di-t-butyl 4-Ethyl-3-(4-iodobutyl)-5-oxo-2-tosyl-1H-pyr-
role-1,2(2H,5H)-dicarboxylate (25a) and Di-t-butyl 4-Ethyl-
3-(4-iodobutyl)-5-oxo-4-tosyl-1H-pyrrole-1,2(4H,5H)-dicar-
boxylate (25b). To a ca. 1:2 mixture of 24a and 24b (9.240 g,
20.0 mmol) was added Ph3P (6.295 g, 24.0 mmol), I2 (6.096 g,
1710, 1578, 1459, 1367, 1321, 1278, 1243, 1154, 1082, 1065,
¹1
840, 816, 710 cm
.
1H NMR (CDCl3): ¤ 0.72 (t, 3H, J =
7.5 Hz), 1.59 (s, 9H), 1.67-1.82 (m, 2H), 1.94-2.35 (m, 4H),
2.05 (s, 3H), 2.41 (s, 3H), 2.49 (dt, 1H, J = 13.4, 4.4 Hz), 3.02
(dt, 1H, J = 13.4, 4.4 Hz), 4.09-4.16 (m, 2H), 6.62 (s, 1H),
7.29 (d, 2H, J = 8.6 Hz), 7.66 (d, 2H, J = 8.6 Hz). HRMS
(FAB+) (M+ + 1), Found: m/z 480.2056. Calcd for C24H34-
NO7S: 480.2074.

1318 Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) BCSJ AWARD ARTICLE
24.0 mmol), and imidazole (3.404 g, 50.0 mmol) in MeCN
(50 mL) at room temperature under a nitrogen atmosphere.
After stirring for 1 h, the solvent was removed under reduced
pressure and the residue was partitioned between AcOEt and
water. The organic extract was successively washed with a
saturated aqueous solution of NaHCO3 and brine, and then
dried over Na2SO4. The solvent was evaporated and the residue
was separated by flash column chromatography (SiO2, hexane/
AcOEt = 4/1, 3/1, 2/1, 1/1, v/v) to give a ca. 1:2 mixture of
25a and 25b (10.195 g, 89% yield) as an oil. Analytical
samples of the iodides were obtained by further separation of a
part of the mixture by flash column chromatography.
1368, 1321, 1252, 1210, 1151, 1085, 1005, 943, 843, 817, 775,
1
705, 661 cm¹1. H NMR (CDCl3): ¤ 0.78 (t, 3H, J = 7.6 Hz),
1.47 (s, 9H), 1.49 (s, 9H), 1.68-2.16 (m, 4H), 2.21-2.69 (m,
4H), 2.42 (s, 3H), 4.44 (t, 2H, J = 6.9 Hz), 7.31 (d, 2H,
J = 8.2 Hz), 7.64 (d, 2H, J = 8.2 Hz). Found: C, 57.24; H,
6.80; N, 4.92%. Calcd for C27H38N2O9S: C, 57.23; H, 6.76;
N, 4.94%. Crystal data: C27H38N2O9S, FW 566.67, triclinic,
ꢀ
P1, a = 16.601(2) ¡, b = 18.798(3) ¡, c = 21.8398(3) ¡, ¡ =
66.44(3)°, ¢ = 71.18(2)°, £ = 84.41(3)°, V = 5909(1) ¡3,
Z = 8, Dcalcd = 1.274 g cm¹3, R = 0.046 (Rw = 0.066) for
19815 reflections with I > 3.00·(I) and 1404 variable param-
eters.
25a: an oil. IR (neat): 2979, 2935, 2877, 2257, 1782, 1748,
1658, 1596, 1458, 1395, 1370, 1305, 1255, 1151, 1083, 1045,
Crystallographic data have been deposited with Cambridge
Crystallographic Data Centre: Deposition numbers CCDC-
789497 and -789498 for compounds 26a and 26b, respectively.
Copies of the data can be obtained free of charge via
http://www.ccdc.cam.ac.uk/conts/retrieving.html (or from the
Cambridge Crystallographic Data Centre, 12, Union Road,
Cambridge, CB2 1EZ, U.K.; Fax: +44 1223 336033; e-mail:
deposit@ccdc.cam.ac.uk).
1
983, 912, 874, 817, 779, 733 cm¹1. H NMR (CDCl3): ¤ 0.94
(t, 3H, J = 7.6 Hz), 1.50 (s, 9H), 1.53 (s, 9H), 1.60-1.96 (m,
4H), 2.13-2.84 (m, 4H), 2.40 (s, 3H), 3.22 (t, 2H, J = 6.6 Hz),
7.29 (d, 2H, J = 8.3 Hz), 7.70 (d, 2H, J = 8.3 Hz). HRMS
(FAB+) (M+ + 1), Found: m/z 648.1495. Calcd for C27H39-
NO7SI: 648.1492.
25b: an oil. IR (neat): 2981, 2938, 2879, 1760, 1742, 1721,
1641, 1596, 1460, 1392, 1369, 1353, 1327, 1304, 1257, 1221,
1201, 1151, 1080, 1003, 940, 871, 842, 811, 779, 732,
Di-t-butyl 3-{3-[4-(2-Allyloxycarbonylethyl)-5-(t-butoxy-
carbonyl)-1H-pyrrol-3-yl]propyl}-4-ethyl-5-oxo-2-tosyl-1H-
pyrrole-1,2(2H,5H)-dicarboxylate (29a) and Di-t-butyl 3-{3-
[4-(2-Allyloxycarbonylethyl)-5-(t-butoxycarbonyl)-1H-pyr-
rol-3-yl]propyl}-4-ethyl-5-oxo-4-tosyl-1H-pyrrole-1,2(4H,5H)-
dicarboxylate (29b). Step 1: To a ca. 1:2 mixture of 26a and
26b (625 mg, 1.245 mmol) and allyl 4-oxobutanoate (27)17c
1
675 cm¹1. H NMR (CDCl3): ¤ 0.83 (t, 3H, J = 7.6 Hz), 1.47
(s, 9H), 1.48 (s, 9H), 1.64-1.95 (m, 4H), 2.24-2.67 (m, 4H),
2.43 (s, 3H), 3.22 (t, 2H, J = 7.1 Hz), 7.30 (d, 2H, J = 8.2 Hz),
7.65 (d, 2H, J = 8.2 Hz). HRMS (FAB+) (M+ + 1), Found:
m/z 648.1495. Calcd for C27H39NO7SI: 648.1492.
n
(353 mg, 2.490 mol), 0.1 M Bu4NOH in THF (3.7 mL, 0.37
Di-t-butyl 4-Ethyl-3-(4-nitrobutyl)-5-oxo-2-tosyl-1H-pyr-
role-1,2(2H,5H)-dicarboxylate (26a) and Di-t-butyl 4-Ethyl-
3-(4-nitrobutyl)-5-oxo-4-tosyl-1H-pyrrole-1,2(4H,5H)-dicar-
boxylate (26b). To ca. 1:2 mixture of the iodides 25a and 25b
(8.64 g, 15 mmol), NaNO2 (2.14 g, 31 mmol), and phlorogluci-
nol (2.76 g, 17 mmol), DMF (100 mL) was added under a
nitrogen atmosphere.23 After stirring overnight at room temper-
ature, the mixture was partitioned between AcOEt and water.
The organic extract was washed with brine and then dried over
MgSO4. The solvent was evaporated and the residue was
separated by flash column chromatography (SiO2, hexane/
AcOEt = 4/1, v/v) to give a ca. 1:2 mixture of 26a and 26b
(4.64 g, 60% yield) as an oil. Analytical samples of 26a and
26b were obtained by further separation of a part of the mixture
by flash column chromatography. Their structures were
confirmed by X-ray crystallographic analysis.
mmol) was added dropwise at 0 °C. After stirring for 4 h at
room temperature, the solvent was removed under reduced
pressure and the residue was partitioned between AcOEt and
water. The organic layer was successively washed with 1 M
HCl, a saturated aqueous solution of NaHCO3, brine, and dried
over MgSO4. The solvent was evaporated and the residue was
separated by TLC on SiO2 (hexane/AcOEt = 3/1, v/v) to give
a mixture of crude nitro alcohols 28a and 28b (600 mg) as an
oil.
Step 2: To the mixture of 28a and 28b (total 600 mg, ca.
0.811 mmol) and DMAP (20 mg, 0.162 mmol) was added Ac2O
(91 mg, 0.892 mmol) dropwise at 0 °C under a nitrogen
atmosphere. After stirring for 2 h at room temperature, the
reaction mixture was quenched by adding MeOH and the
solvent was removed under reduced pressure. The residue was
partitioned between AcOEt and water, and the organic extract
was successively washed with a saturated aqueous solution of
NaHCO3, brine, and dried over MgSO4. The solvent was
evaporated and the product was separated by TLC on SiO2
(hexane/AcOEt = 2/1, v/v) to give a mixture of acetates of
28a and its isomer 28b and the corresponding nitro olefins
(570 mg) as an oil.
Step 3: To a solution of t-butyl isocyanoacetate (321 mg,
2.280 mmol) in MeCN (10 mL) at ¹40 °C under a nitrogen
atmosphere, DBU (578 mg, 3.8 mmol) was added, followed by
dropwise addition of the mixture of nitro acetates and the
corresponding nitro olefins obtained above (total 570 mg) in
THF (2 mL).21 After stirring overnight at room temperature, the
solvent was removed under reduced pressure and the residue
was partitioned between AcOEt and water. The organic extract
was successively washed with saturated aqueous solutions of
26a: a white solid. Mp 117-120 °C (from Et2O/hexane). IR
(KBr): 2980, 2937, 2878, 1785, 1748, 1658, 1596, 1552, 1460,
1372, 1332, 1304, 1255, 1149, 1083, 1046, 1028, 941, 873,
¹1
820, 779, 713, 655 cm
.
1H NMR (CDCl3): ¤ 0.93 (t, 3H,
J = 7.6 Hz), 1.47 (s, 9H), 1.48 (s, 9H), 1.58-2.29 (m, 6H),
2.59-2.88 (m, 2H), 2.41 (s, 3H), 4.44 (t, 2H, J = 6.9 Hz), 7.27
(d, 2H, J = 8.2 Hz), 7.70 (d, 2H, J = 8.2 Hz). HRMS (FAB+)
(M+ + 1), Found: m/z 567.2368. Calcd for C27H39N2O9S:
567.2376. Crystal data: C27H38N2O9S, FW 566.67, orthorhom-
bic, Pca21, a = 9.567(2) ¡, b = 15.836(3) ¡, c = 19.335(3) ¡,
V = 2929.3(9) ¡3, Z = 4, Dcalcd = 1.285 g cm¹3, R = 0.044
(Rw = 0.081) for 6470 reflections with I > 3.00·(I) and 352
variable parameters.
26b: a white solid. Mp 98-100 °C (from Et2O/hexane). IR
(KBr): 2980, 2938, 2875, 1792, 1760, 1728, 1596, 1551, 1457,

K. Nishiyama et al.
Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) 1319
NaHSO3, NaHCO3, brine, and then dried over MgSO4. The
solvent was evaporated and the residue was separated by TLC
on SiO2 (hexane/AcOEt = 2/1, v/v) to give a ca. 1:2 mixture
of 29a and 29b (268 mg) as an oil. Total yield over these 3
steps was 28%.
(30 mL) was added POCl3 (781 mg, 5.094 mmol) dropwise at
room temperature and the mixture was stirred for 30 min under
a nitrogen atmosphere.24 A solution of a ca. 1:2 mixture of 29a
and 29b (2.560 g, 3.208 mmol) in DMF (2 mL) was then added
dropwise at 0 °C and the reaction mixture was stirred for 10 min
at 0 °C and then for 2 h at 65 °C. The reaction mixture was
quenched by addition of a 10% aqueous NaOAc solution
(52 mL) with stirring for 2 h at 65 °C. The mixture was
partitioned between AcOEt and water, and the organic extract
was washed with brine, and then dried over MgSO4. The
solvent was evaporated and the residue was separated by flash
column chromatography (SiO2, hexane/AcOEt = 3/1, v/v) to
give a ca. 1:2 mixture of aldehydes 8a and 8b (1.780 g, 67%
yield) as an oil.
In a similar manner, the reaction of 29a (150 mg, 0.188
mmol) with POCl3 (46 mg, 0.301 mmol) and DMF (total
1.8 mL) gave 8a (110 mg, 71% yield). Furthermore, the
reaction of 29b (150 mg, 0.188 mmol) with POCl3 (46 mg,
0.301 mmol) and DMF (total 1.8 mL) gave 8b (127 mg, 82%
yield).
In a similar manner, 2-tosyl isomer 29a was prepared from
the isolated 26a: The nitro compound 26a (200 mg, 0.398
mmol), allyl 4-oxobutanoate (27) (113 mg, 0.796 mmol), and
0.1 M nBu4NOH in THF (1.2 mL, 0.12 mmol) gave nitro
alcohol 28a (195 mg, 0.264 mmol) in Step 1. The nitro alcohol
28a (50 mg, 0.068 mmol), DMAP (2 mg, 0.014 mmol), and
Ac2O (91 mg, 0.892 mmol) afforded a mixture of the acetate of
28a and the corresponding nitro olefin (total 27 mg) in Step 2.
The mixture of the nitro acetate and the corresponding nitro
olefin (total 27 mg), t-butyl isocyanoacetate (15 mg, 0.108
mmol), and DBU (27 mg, 0.036 mmol) afforded 29a (23 mg,
0.028 mmol) in Step 3. Total yield over these 3 steps was 27%.
Furthermore, the isomer 29b was prepared from the isolated
26b: The nitro compound 26b (200 mg, 0.398 mmol), allyl 4-
oxobutanoate (27) (113 mg, 0.796 mmol), and 0.1 M nBu4NOH
in THF (1.2 mL, 0.12 mmol) gave 28b (187 mg, 0.253 mmol) in
Step 1. The nitro alcohol 28b (76 mg, 0.103 mmol), DMAP
(2 mg, 0.014 mmol), and Ac2O (12 mg, 0.113 mmol) afforded a
mixture of the acetate of 28b and the corresponding nitro olefin
(total 62 mg) in Step 2. The mixture of the nitro acetate and the
corresponding nitro olefin (total 62 mg), t-butyl isocyanoacetate
(35 mg, 0.250 mmol), and DBU (63 mg, 0.420 mmol) produced
29b (51 mg, 0.063 mmol) in Step 3. Total yield over these 3
steps was 42%.
8a: a white solid. Mp 59 °C (from AcOEt). IR (KBr): 3299,
2979, 2937, 1783, 1746, 1668, 1596, 1550, 1460, 1393, 1370,
1303, 1256, 1153, 1082, 1046, 989, 932, 843, 816, 783, 710,
1
665 cm¹1. H NMR (CDCl3): ¤ 0.90 (t, 3H, J = 7.3 Hz), 1.44
(s, 9H), 1.50 (s, 9H), 1.58 (s, 9H), 1.75-1.95 (m, 2H), 2.09-
2.23 (m, 2H), 2.40 (s, 3H), 2.60-2.89 (m, 6H), 3.01 (t, 2H,
J = 8.2 Hz), 4.55 (d, 2H, J = 6.0 Hz), 5.20 (d, 1H, J =
10.8 Hz), 5.27 (d, 1H, J = 17.6 Hz), 5.87 (ddt, 1H, J = 17.6,
10.8, 6.0 Hz), 7.26 (d, 2H, J = 8.2 Hz), 7.70 (d, 2H, J =
8.2 Hz), 9.51 (brs, 1H), 9.76 (s, 1H). HRMS (FAB+) (M+ + 1),
Found: m/z 813.3623. Calcd for C42H57N2O12S: 813.3633.
8b: a white solid. Mp 60 °C (from AcOEt). IR (KBr): 3309,
2979, 2937, 1790, 1737, 1663, 1597, 1550, 1459, 1370, 1324,
1255, 1208, 1152, 1086, 1051, 999, 930, 844, 816, 706,
29a: an oil. IR (neat): 3378, 3318, 2979, 2936, 1791, 1733,
1689, 1597, 1565, 1456, 1402, 1369, 1324, 1281, 1254, 1213,
¹1
1153, 1086, 1058, 1001, 941, 843, 816, 757, 706, 662 cm
.
1H NMR (CDCl3): ¤ 0.87 (t, 3H, J = 7.6 Hz), 1.45 (s, 9H), 1.51
(s, 9H), 1.54 (s, 9H), 1.70-1.81 (m, 2H), 2.02-2.20 (m, 2H),
2.34-2.66 (m, 5H), 2.40 (s, 3H), 2.79-2.86 (m, 1H), 3.00
(d, 2H, J = 8.2 Hz), 4.56 (d, 2H, J = 5.5 Hz), 5.20 (d, 1H, J =
10.8 Hz), 5.28 (d, 1H, J = 17.2 Hz), 5.91 (ddt, 1H, J = 17.2,
10.8, 5.5 Hz), 6.67 (d, 1H, J = 2.8 Hz), 7.25 (d, 2H, J = 8.3
Hz), 7.68 (d, 2H, J = 8.3 Hz), 8.92 (brs, 1H). HRMS (FAB+)
(M+ + 1), Found: m/z 785.3684. Calcd for C41H57N2O11S:
785.3684.
1
661 cm¹1. H NMR (CDCl3): ¤ 0.76 (t, 3H, J = 7.3 Hz), 1.43
(s, 9H), 1.47 (s, 9H), 1.58 (s, 9H), 1.80-2.05 (m, 2H), 2.22-
2.66 (m, 6H), 2.43 (s, 3H), 2.85 (t, 2H, J = 7.8 Hz), 3.03 (t, 2H,
J = 7.6 Hz), 4.56 (d, 2H, J = 6.0 Hz), 5.19 (d, 1H, J = 10.0
Hz), 5.27 (d, 1H, J = 17.2 Hz), 5.87 (ddt, 1H, J = 17.2, 10.0,
6.0 Hz), 7.30 (d, 2H, J = 8.2 Hz), 7.63 (d, 2H, J = 8.2 Hz),
9.48 (brs, 1H), 9.80 (s, 1H). HRMS (FAB+) (M+ + 1), Found:
m/z 813.3627. Calcd for C42H57N2O12S: 813.3633.
29b: an oil. IR (neat): 3378, 3318, 2979, 2936, 1791, 1733,
1689, 1597, 1565, 1456, 1402, 1369, 1324, 1281, 1254, 1213,
1-(2-Allyloxycarbonylethyl)-7-ethyl-6-oxo-3,5,6,8,9,10-
hexahydro-3,5-diazadicyclopenta[a,d]cyclooctene-2-carbox-
ylic Acid (31). A ca. 1:2 mixture of 8a and 8b (1.780 g,
2.160 mmol) was dissolved in 99% formic acid (10.8 mL) at
10 °C under a nitrogen atmosphere. After stirring for 5 h at
room temperature, the solvent was removed under reduced
pressure and the residue was partitioned between AcOEt and
water and the organic extract was washed with brine, and then
dried over Na2SO4. The evaporation of the solvent gave a crude
mixture of dicarboxylic acid 30a and its isomer 30b (900 mg),
which was dried under vacuum over solid NaOH overnight and
used for the next reaction without further purification. To the
mixed solution of the carboxylic acids (900 mg) obtained above
¹1
1153, 1086, 1058, 1001, 941, 843, 816, 757, 706, 662 cm
.
1H NMR (CDCl3): ¤ 0.80 (t, 3H, J = 7.6 Hz), 1.42 (s, 9H), 1.45
(s, 9H), 1.54 (s, 9H), 1.78-1.98 (m, 2H), 2.18-2.28 (m, 1H),
2.36-2.45 (m, 1H), 2.43 (s, 3H), 2.47-2.66 (m, 6H), 3.02
(t, 2H, J = 8.0 Hz), 4.59 (d, 2H, J = 5.5 Hz), 5.22 (d, 1H,
J = 10.1 Hz), 5.30 (d, 1H, J = 17.4 Hz), 5.89 (ddt, 1H, J =
17.4, 10.1, 5.5 Hz), 6.73 (d, 1H, J = 2.7 Hz), 7.29 (d, 2H, J =
8.3 Hz), 7.65 (d, 2H, J = 8.3 Hz), 8.89 (brs, 1H). (FAB+)
(M+ + 1), Found: m/z 785.3684. Calcd for C41H57N2O11S:
785.3684.
Di-t-butyl 3-{3-[4-(2-Allyloxycarbonylethyl)-5-(t-butoxy-
carbonyl)-2-formyl-1H-pyrrol-3-yl]propyl}-4-ethyl-5-oxo-2-
tosyl-1H-pyrrole-1,2(2H,5H)-dicarboxylate (8a) and Di-t-
butyl 3-{3-[4-(2-Allyloxycarbonylethyl)-5-(t-butoxycarbon-
yl)-2-formyl-1H-pyrrol-3-yl]propyl}-4-ethyl-5-oxo-4-tosyl-
n
in THF/DMF (2/1, v/v, 27 mL) was added Bu3P (693 mg,
3.425 mmol) at ¹78 °C under a nitrogen atmosphere, followed
by dropwise addition of DBU (626 mg, 4.112 mmol).13,25 After
stirring overnight at room temperature, the solvent was
1H-pyrrole-1,2(4H,5H)-dicarboxylate (8b).
To DMF

1320 Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) BCSJ AWARD ARTICLE
removed under reduced pressure and the residue was dissolved
in AcOEt. The organic solution was treated with a saturated
aqueous solution of NaHCO3 to convert the resulting carbox-
ylic acid to the corresponding sodium salt and the organic
phase was discarded. The aqueous solution was acidified to
pH 3 by adding 1 M HCl and the precipitated solid carboxylic
acid was filtered off and dried under vacuum to give 31
(410 mg, 49% yield in 2 steps) as a yellow solid. It was used for
the next step without further purification.
solution (pH 7.0) and extracted with AcOEt. The organic layer
was washed with brine, and then dried over Na2SO4. The
solvent was evaporated and the blue residue was separated by
thin layer chromatography (SiO2, hexane/CHCl3/MeOH =
7/4/0.5, v/v/v) to afford 32 in 71% (20 mg) yield as a blue
solid. Mp 173-175 °C (from CH2Cl2/hexane). IR (KBr): 3345,
2927, 1734, 1685, 1586, 1456, 1257, 1160, 1099, 953, 931,
1
874, 850 cm¹1. H NMR (CDCl3): ¤ 1.04 (t, 3H, J = 7.4 Hz),
1.92-1.98 (m, 2H), 2.07 (s, 3H), 2.08 (s, 3H), 2.30 (q, 2H,
J = 7.4 Hz), 2.32-2.37 (m, 2H), 2.48 (brt, 2H, J = 5.9 Hz),
2.58 (t, 2H, J = 7.8 Hz), 2.59 (t, 2H, J = 7.8 Hz), 2.95 (t, 2H,
J = 7.8 Hz), 2.97 (t, 2H, J = 7.8 Hz), 4.55-4.59 (m, 4H), 5.21
(d, 2H, J = 10.2 Hz), 5.28 (d, 2H, J = 17.3 Hz), 5.67 (d, 1H,
J = 11.7 Hz), 5.70 (d, 1H, J = 17.8 Hz), 5.84-5.94 (m, 2H),
6.11 (s, 1H), 6.38 (s, 1H), 6.64 (dd, 1H, J = 17.8, 11.7 Hz),
6.86 (s, 1H), 8.78 (brs, 1H). Two NH protons were not
observed clearly. Found: C, 70.95; H, 6.49; N, 8.22%. Calcd
for C40H44N4O6: C, 70.99; H, 6.55; N, 8.28%.
In a similar manner, 8a (60 mg, 0.073 mmol) was converted
to 2-tosyl isomer of the carboxylic acid 30a (40 mg). The crude
n
acid 30a (58 mg) was treated with Bu3P (45 mg, 0.222 mmol)
and DBU (41 mg, 0.269 mmol) to give 31 (19 mg, 46% yield in
2 steps). Furthermore, 8b (40 mg, 0.049 mmol) was converted
to 30b (39 mg), which was treated with nBu3P (25 mg,
0.125 mmol) and DBU (23 mg, 0.151 mmol) to give 31
(11 mg, 60% yield in 2 steps). Mp 171-175 °C (from THF/
hexane). IR (KBr): 3255, 2970, 2935, 2876, 2583, 1677, 1557,
1463, 1371, 1262, 1179, 1154, 1092, 1057, 988, 935, 844, 820,
3-{2-[1-(2-Carboxyethyl)-7-ethyl-6-oxo-3,5,6,8,9,10-hexa-
hydro-3,5-diazadicyclopenta[a,d]cycloocten-2-ylmethylene]-
4-methyl-5-(4-methyl-5-oxo-3-vinyl-2,5-dihydro-1H-pyrrol-
2-ylidenemethyl)-2H-pyrrol-3-yl}propanoic Acid (3). To a
mixed solution 32 (20 mg, 0.0296 mmol) and [Pd(PPh3)4]
(7 mg, 0.0059 mmol) in THF (0.7 mL), a solution of TsNa
(10 mg, 0.059 mmol) in MeOH (0.7 mL) was added under a
nitrogen atmosphere at room temperature. After stirring for
10 min, the solvent was evaporated and the residue was
separated by flash column chromatography (SiO2, CHCl3/
MeOH/AcOH = 200/15/1, v/v/v). The blue fraction was
evaporated and the resulting solid residue was recrystallized
from CHCl3/hexane. Free acid 3: a blue solid, 12 mg, 70%
yield. Mp 260 °C (decomp.). IR (KBr): 3400, 3232, 2968,
2933, 1702, 1601, 1458, 1416, 1292, 1094, 954, 890, 839
cm¹1. 1H NMR (C5D5N): ¤ 1.17 (t, 3H, J = 7.5 Hz), 1.88-1.96
(m, 2H), 2.06 (s, 3H), 2.12 (s, 3H), 2.32 (t, 2H, J = 6.1 Hz),
2.44 (q, 2H, J = 7.5 Hz), 2.53 (t, 2H, J = 6.1 Hz), 2.88 (t, 4H,
J = 7.3 Hz), 3.20 (t, 2H, J = 7.3 Hz), 3.21 (t, 2H, J = 7.3 Hz),
5.60 (d, 1H, J = 11.7 Hz), 5.74 (d, 1H, J = 17.8 Hz), 6.27
(s, 1H), 6.72 (dd, 1H, J = 17.8, 11.7 Hz), 6.72 (s, 1H), 7.59
(s, 1H), 8.42 (s, 1H), 11.76 (s, 1H). Two CO2H protons and
one NH proton were not observed clearly. UV-vis (MeOH)
1
784 cm¹1. H NMR (CDCl3/THF-d8): ¤ 1.10 (t, 3H, J = 7.3
Hz), 1.93-1.98 (m, 2H), 2.35 (q, 2H, J = 7.3 Hz), 2.36-2.38
(m, 2H), 2.45-2.53 (m, 2H), 2.59 (t, 2H, J = 8.2 Hz), 3.05
(t, 2H, J = 8.2 Hz), 4.53 (d, 2H, J = 5.4 Hz), 5.16 (d, 1H, J =
9.9 Hz), 5.26 (d, 1H, J = 17.4 Hz), 5.90 (ddt, 1H, J = 17.4, 9.9,
5.4 Hz), 6.09 (s, 1H), 7.73 (s, 1H), 9.04 (s, 1H), 10.65 (s, 1H).
HRMS (FAB+) (M+ + 1), Found: m/z 385.1759. Calcd for
C21H25N2O5: 385.1764.
Allyl 1-(7-Ethyl-2-formyl-6-oxo-3,5,6,8,9,10-hexahydro-
3,5-diazadicyclopenta[a,d]cycloocten-1-yl)propanoate (6).
To a solution of 31 (110 mg, 0.3 mmol) in TFA (3 mL) was
added (MeO)3CH (1.5 mL) at 0 °C under a nitrogen atmosphere
and allowed to stir for 25 min at 0 °C and for 20 min at room
temperature. The reaction mixture was quenched with water
and extracted with AcOEt. The organic layer was successively
washed with a saturated aqueous solution of NaHCO3, brine,
and dried over MgSO4. The solvent was evaporated and the
residue was separated by flash column chromatography (SiO2,
hexane/AcOEt = 2/1, v/v) to give 6 (67 mg) in 63% yield as a
yellow solid. Mp 128-130 °C (from AcOEt/hexane). IR (KBr):
3605, 3565, 3005, 2967, 2925, 1714, 1645, 1421, 1362, 1223,
1
1092, 903, 785 cm¹1. H NMR (CDCl3): ¤ 1.13 (t, 3H, J =
7.6 Hz), 1.94 (quint, 2H, J = 6.4 Hz), 2.36-2.42 (m, 4H), 2.51
(t, 2H, J = 6.4 Hz), 2.64 (t, 2H, J = 7.7 Hz), 3.08 (t, 2H,
J = 7.7 Hz), 4.57 (d, 2H, J = 5.9 Hz), 5.23 (dd, 1H, J = 10.5,
1.5 Hz), 5.28 (dd, 1H, J = 17.3, 1.5 Hz), 5.88 (ddt, 1H,
J = 17.3, 10.5, 5.9 Hz), 6.19 (s, 1H), 8.31 (brs, 1H), 9.63 (s,
1H), 9.98 (brs, 1H). Found: C, 68.39; H, 6.52; N, 7.49%. Calcd
for C21H24N2O4: C, 68.46; H, 6.57; N, 7.60%.
-
381 (¾ = 40533), 630 (¾ = 29260) nm. HRMS (FAB+)
max
(M+ + 1), Found: m/z 597.2741. Calcd for C34H37N4O6:
597.2713.
Allyl 3-{2-[3-(2-Allyloxycarbonylethyl)-5-(3-ethylidene-4-
methyl-5-oxopyrrolidin-2-ylidenemethyl)-4-methylpyrrol-2-
ylidenemethyl]-7-ethyl-6-oxo-3,5,6,8,9,10-hexahydro-3,5-di-
azadicyclopenta[a,d]cycloocten-1-yl}propanoate (33).
To
Allyl
3-{2-[1-(2-Allyloxycarbonylethyl)-7-ethyl-6-oxo-
11 (13 mg, 0.029 mmol) and 6 (9 mg, 0.024 mmol) was added
TFA (0.36 mL) at room temperature under a nitrogen at-
mosphere. After stirring for 20 min, MeOH (0.72 mL) was
added and the reaction mixture was stirred for 1.5 h. The
reaction mixture was quenched by adding a phosphate buffer
solution (pH 7.0) and extracted with AcOEt. The organic layer
was washed with brine, and then dried over Na2SO4. The
solvent was evaporated and the blue residue was separated
by TLC on SiO2 (CHCl3/AcOEt/EtOH = 60/8/1, v/v/v) to
afford 33 (11 mg, 0.016 mmol) in 67% yield as a blue solid. Mp
73-75 °C (from CH2Cl2/hexane). IR (KBr): 3243, 2931, 2855,
3,5,6,8,9,10-hexahydro-3,5-diazadicyclopenta[a,d]cycloocten-
2-ylmethylene]-4-methyl-5-(4-methyl-5-oxo-3-vinyl-2,5-di-
hydro-1H-pyrrol-2-ylidenemethyl)-2H-pyrrol-3-yl}propa-
noate (32). To a mixed solution of 6 (15 mg, 0.041 mmol) and
(Z)-allyl
3-{4-methyl-5-[4-methyl-5-oxo-3-vinyl-1H-pyrrol-
2(5H)-ylidenemethyl]-1H-pyrrol-3-yl}propanoate (7)14 (13 mg,
0.041 mmol) in MeOH (1.5 mL), a solution of H2SO4 (8 mg,
0.082 mmol) in MeOH (0.6 mL) was added dropwise at room
temperature under a nitrogen atmosphere. After stirring for 1 h,
the reaction mixture was quenched with a phosphate buffer

K. Nishiyama et al.
Bull. Chem. Soc. Jpn. Vol. 83, No. 11 (2010) 1321
Pigments, Springer Verlag, New York, 1989; W. Rüdiger, F.
Thümmler, Angew. Chem., Int. Ed. Engl. 1991, 30, 1216; M.
Furuya, P.-S. Song, in Assembly and Properties of Holophyto-
chrome in Photomorphogenesis in Plants, 2nd ed., ed. by R. E.
Kendrick, G. H. M. Kronenberg, Kluwer Academic Publishers,
Dordrecht, The Netherlands, 1994, Chap. 4.3, pp. 105-140; M.
Stanek, K. Grubmayr, Chem.®Eur. J. 1998, 4, 1653; M. Stanek, K.
Grubmayr, Chem.®Eur. J. 1998, 4, 1660; T. Lamparter, FEBS Lett.
2004, 573, 1; N. C. Rockwell, J. C. Lagarias, Plant Cell 2006, 18,
4; N. C. Rockwell, Y.-S. Su, J. C. Lagarias, Annu. Rev. Plant Biol.
2006, 57, 837.
1733, 1681, 1590, 1453, 1412, 1376, 1338, 1319, 1256, 1212,
1155, 1091, 1052, 987, 957, 934, 895, 835, 700 cm¹1. 1H NMR
(CDCl3): ¤ 1.11 (t, 3H, J = 7.6 Hz), 1.43 (d, 3H, J = 7.6 Hz),
1.92 (d, 3H, J = 7.3 Hz), 1.94-2.02 (m, 2H), 2.05 (s, 3H),
2.35-2.40 (m, 2H), 2.38 (q, 2H, J = 7.6 Hz), 2.50 (t, 2H,
J = 6.3 Hz), 2.58 (t, 2H, J = 7.8 Hz), 2.59 (t, 2H, J = 7.8 Hz),
2.92 (t, 2H, J = 7.8 Hz), 2.96 (t, 2H, J = 7.8 Hz), 3.25 (q, 1H,
J = 7.6 Hz), 4.56-4.58 (m, 4H), 5.20 (dd, 1H, J = 10.5,
1.5 Hz), 5.21 (dd, 1H, J = 10.5, 1.5 Hz), 5.27 (dd, 1H, J =
17.1, 1.5 Hz), 5.29 (dd, 1H, J = 17.1, 1.5 Hz), 5.84 (s, 1H),
5.89 (ddt, 2H, J = 17.1, 10.5, 5.9 Hz), 6.40 (q, 1H, J = 7.3 Hz),
6.45 (s, 1H), 6.68 (s, 1H), 9.56 (brs, 1H). Two NH protons were
not observed clearly. HRMS (FAB+) (M+ + 1), Found: m/z
679.3485. Calcd for C40H47N4O6: 679.3496.
6
W. Rüdiger, F. Thümmler, in Photomorphogenesis in
Plants, 2nd ed., ed. by R. E. Kendrick, G. H. M. Kronenberg,
Kluwer Academic Publishers, Dordrecht, The Netherlands, 1994.
7
a) N. Frankenberg, K. Mukougawa, T. Kohchi, J. C.
3-{2-[3-(2-Carboxyethyl)-5-(3-ethylidene-4-methyl-5-oxo-
pyrrolidin-2-ylidenemethyl)-4-methylpyrrol-2-ylidenemeth-
yl]-7-ethyl-6-oxo-3,5,6,8,9,10-hexahydro-3,5-diazadicyclo-
penta[a,d]cycloocten-1-yl}propanoic Acid (2). To a mixed
solution of 33 (10 mg, 0.015 mmol) and [Pd(PPh3)4] (3 mg,
0.003 mmol) in THF (0.4 mL), a solution of TsNa (5 mg,
0.030 mmol) in MeOH (0.4 mL) was added under a nitrogen
atmosphere at room temperature. After stirring for 10 min,
thiourea (0.9 mg, 0.012 mmol) was added. The solution was
directly separated by flash column chromatography (SiO2,
CHCl3/MeOH/AcOH = 250/15/1, v/v/v). The blue fraction
was evaporated and the resulting solid residue was recrystal-
lized from CHCl3/hexane. Free acid 2: a blue solid, 12 mg, in
quantitative yield. Mp 175-178 °C (from CHCl3/hexane). IR
(KBr): 3434, 2934, 2861, 1668, 1600, 1543, 1455, 1440, 1412,
1375, 1335, 1247, 1222, 1178, 1151, 1104, 1051, 969, 895,
848, 806, 745, 700, 667 cm¹1. 1H NMR (C5D5N): ¤ 1.16 (t, 3H,
J = 7.6 Hz), 1.32 (d, 3H, J = 7.3 Hz), 1.69 (d, 3H, J = 7.1 Hz),
1.93-1.99 (m, 2H), 2.13 (s, 3H), 2.34-2.40 (m, 2H), 2.45 (q,
2H, J = 7.6 Hz), 2.55-2.60 (m, 2H), 2.89-2.95 (m, 4H), 3.18-
3.28 (m, 5H), 6.04 (s, 1H), 6.29 (q, 1H, J = 7.1 Hz), 7.00 (s,
1H), 7.51 (s, 1H), 8.53 (s, 1H). Two NH protons and two CO2H
were not observed clearly. UV-vis (MeOH) -max 382 (¾ =
24613), 679 (¾ = 39057) nm. HRMS (FAB+) (M+ + 1),
Found: m/z 599.2868. Calcd for C34H39N4O6: 599.2870.
Lagarias, Plant Cell 2001, 13, 965. b) T. Hübschmann, T. Börner,
E. Hartmann, T. Lamparter, Eur. J. Biochem. 2001, 268, 2055.
8
S. H. Wu, M. T. McDowell, J. C. Lagarias, J. Biol. Chem.
1997, 272, 25700.
9
A. Blumenstein, K. Vienken, R. Tasler, J. Purschwitz, D.
Veith, N. Frankenberg-Dinkel, R. Fischer, Curr. Biol. 2005, 15,
1833; I. Oberpichler, I. Molina, O. Neubauer, T. Lamparter, FEBS
Lett. 2006, 580, 437.
10 T. Lamparter, N. Michael, O. Caspani, T. Miyata, K. Shirai,
K. Inomata, J. Biol. Chem. 2003, 278, 33786.
11 J. R. Wagner, J. S. Brunzelle, K. T. Forest, R. D. Vierstra,
Nature 2005, 438, 325; J. R. Wagner, J. Zhang, J. S. Brunzelle,
R. D. Vierstra, K. T. Forest, J. Biol. Chem. 2007, 282, 12298; X.
Yang, E. A. Stojković, J. Kuk, K. Moffat, Proc. Natl. Acad. Sci.
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Acad. Sci. U.S.A. 2008, 105, 14715; X. Yang, J. Kuk, K. Moffat,
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12 W. Rüdiger, F. Thümmler, E. Cmiel, S. Schneider, Proc.
Natl. Acad. Sci. U.S.A. 1983, 80, 6244.
13 K. Inomata, Bull. Chem. Soc. Jpn. 2008, 81, 25, and
references cited therein.
14 M. A. S. Hammam, H. Nakamura, Y. Hirata, H. Khawn, Y.
Murata, H. Kinoshita, K. Inomata, Bull. Chem. Soc. Jpn. 2006, 79,
1561.
15 Preliminary communication of the synthesis of 15E-anti
BV derivative: H. Kinoshita, M. A. S. Hammam, K. Inomata,
Chem. Lett. 2005, 34, 800.
16 K. Inomata, M. A. S. Hammam, H. Kinoshita, Y. Murata,
H. Khawn, S. Noack, N. Michael, T. Lamparter, J. Biol. Chem.
2005, 280, 24491; K. Inomata, S. Noack, M. A. S. Hammam, H.
Khawn, H. Kinoshita, Y. Murata, N. Michael, P. Scheerer, N.
Krauss, T. Lamparter, J. Biol. Chem. 2006, 281, 28162.
17 a) H. Khawn, L.-Y. Chen, H. Kinoshita, K. Inomata, Chem.
Lett. 2008, 37, 198. b) K. Inomata, H. Khawn, L.-Y. Chen, H.
Kinoshita, B. Zienicke, I. Molina, T. Lamparter, Biochemistry
2009, 48, 2817. c) L.-Y. Chen, H. Kinoshita, K. Inomata, Chem.
Lett. 2009, 38, 602. d) P. Scheerer, N. Michael, J. H. Park, S.
Nagano, H.-W. Choe, K. Inomata, B. Borucki, N. Krauß, T.
Lamparter, ChemPhysChem 2010, 11, 1090.
The present work was financially supported in part by Grant-
in-Aid for Scientific Research (B) (No. 15350021) from Japan
Society for the Promotion of Science (JSPS).
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