A stereodivergent route to four stereoisomeric 3′- acetoxycyclopentenylglycine derivatives

Article abstract of DOI:10.1055/s-0031-1289645

A short and efficient synthetic route to four stereoisomeric 3-acetoxycyclopentenylglycine derivatives from l-serine has been developed. The method features a stereoselective conjugate addition and ring-closing metathesis as key steps. Georg Thieme Verlag Stuttgart · New York.

Full text of DOI:10.1055/s-0031-1289645

3
04
PAPER
A Stereodivergent Route to Four Stereoisomeric 3¢-Acetoxycyclopentenylglycine
Derivatives
Indranil Kundu, Ratnava Maitra, Manoranjan Jana, Shital K Chattopadhyay*
Department of Chemistry, University of Kalyani, Kalyani 741235, West Bengal, India
Fax +91(33)25828282; E-mail: skchatto@yahoo.com
Received 1 October 2011; revised 15 November 2011
BocHN
CO2H
H
H2N
CO2H
BocHN
CO2H
H
Abstract: A short and efficient synthetic route to four stereoiso-
meric 3¢-acetoxycyclopentenylglycine derivatives from L-serine
has been developed. The method features a stereoselective conju-
gate addition and ring-closing metathesis as key steps.
X
OAc
OAc
Key words: amino acids, chiral pool, metathesis, Michael addition,
stereoselective synthesis
1
2
3
X = NH2, CO2H,
OH, NH2OH
Figure 1 Some cyclopentenylglycine derivatives of importance
Non-natural amino acids with highly lipophilic side
chains have recently started to attract attention as compo-
1
,2
NHBn
Ts
nents of enzyme inhibitors. Of the various cycloalkyl
CO2Et
ref. 15
CO2Et
N
3
4
glycines, cyclopentylglycines (Cpg) and cyclopentenyl-
HO2C
5
O
O
glycines are important for several reasons, including their
N
N
6
7
Boc
Boc
natural occurrence, their use as competitive inhibitors of
NHBoc
4
5
6
isoleucine uptake in E. coli, and as starting materials in the
8
design and synthesis of angiotensin II antagonists and
Scheme 1 Background of the present work
9
neuraminidase inhibitors, to mention a few. It has further
1
0
been observed that appendage of functional groups at
the 3¢-position in cyclopentylglycines can increase the po-
tency of enzyme inhibition, depending on the configura-
tion of the chiral centres. Thus, synthesis and biological
evaluation of stereoisomeric cyclopentylglycines of gen-
Addition of divinylmagnesium cuprate to compound 4
proceeded well under the previously reported conditions
to provide the corresponding syn-adduct 7 in very good
yield as a single isolable stereoisomer (Scheme 2). Reduc-
17
tion of 7 with LiAlH to the corresponding primary alco-
11a
4
eral structure 1 (Figure 1), for example, 3¢-amino-, 3¢-
hol 8, followed by its oxidation under conventional
conditions, proceeded uneventfully to provide the desired
aldehyde 9 in good overall yield. Addition of vinylmagne-
sium bromide to aldehyde 9 proceeded with little diaste-
reocontrol, as expected, to provide a mixture (ca. 1:1) of
the epimeric alcohols 10 and 11 (configuration not deter-
mined at this stage), which were cleanly separated by col-
umn chromatography. The faster running diastereomer 10
was then subjected to ring closing metathesis (RCM) with
1
1b,c
11d
11e
carboxy,
3¢-hydroxymethyl-, 3¢-hydroxylamino-
11f
and 3¢-hydroxycyclopentylglycine, is a matter of con-
siderable current interest. Moreover, 3¢-substituted cyclo-
pentenylglycine derivatives are also of synthetic and
biological interest since they form the core structure of
carbocyclic analogues of some important natural products
1
2
13
such as polyoxins, nikkomycins and furanomycin. In a
1
4
continuation of our efforts on the asymmetric synthesis
of non-natural a-amino acids of interest, herein, we de-
scribe the stereoselective synthesis of two epimeric 3¢-ac-
etoxycyclopentenylglycine derivatives, 2 and 3, and their
enantiomers, ent-2 and ent-3, which are relevant to some
of these applications.
18
the Grubbs catalyst benzylidene bistricyclohexylphos-
phinoruthenium (IV) dichloride (12). Pleasingly, the cor-
responding cyclopentenol derivative 13 was obtained as a
viscous liquid in high yield. Similar treatment of diene 11
provided rapid access to the epimeric cyclopentenol 15
We have recently reported15 the synthesis of 2-azetidi- under comparable conditions. The RCM of dienol deriva-
nylglycine derivative 6 via diastereoselective conjugate tives leading to the corresponding cylopentenols have oc-
1
6
18
addition of benzylamine to the known unsaturated ester casionally been found to be problematic. Successful
4
(Scheme 1). It appeared to us that an analogous stereo- RCM of dienols 10 and 11 is therefore of significance.
selective addition of a vinyl cuprate to the unsaturated es-
ter 4 could be explored for the preparation of the title
compounds.
The corresponding acetate derivatives 14 and 16 were
separately prepared from cyclopentenols 13 and 15, re-
spectively. One-pot deprotection and oxidation of the ox-
azolidine unit in each of the compounds 14 and 16
separately with Jones reagent then led to the desired 3¢-
acetoxycyclopentenylglycine derivatives 2 and 3, respec-
tively.
1
9
SYNTHESIS 2012, 44, 304–310
x
x
.x
x
.2
0
1
1
Advanced online publication: 14.12.2011
DOI: 10.1055/s-0031-1289645; Art ID: Z94211SS
©
Georg Thieme Verlag Stuttgart · New York

PAPER
Stereoisomeric 3¢-Acetoxycyclopentenylglycine Derivatives
305
Y
X
CO2Et
X
i
ii
iv
4
O
O
O
N
H
N
N
Boc
Boc
Boc
7
8, X = CH OH
9
10, X = OH, Y = H
11, X = H, Y = OH
2
iii
, X = CHO
H
H
H
H
OH
OH
vi
vi
OAc
HO2C
v
v
vii
vii
O
O
O
O
OAc
10
NBoc
NBoc
NHBoc
13
14
2
H
H
OAc
H
H
OAc
H
HO2C
11
NBoc
NBoc
NHBoc
15
16
3
Scheme 2 Reagents and conditions: (i) vinylmagnesium bromide, CuI, TMSCl, THF, –78 °C to r.t., 2 h, 89%; (ii) LiAlH , 0 °C, Et O, 1.5 h,
4
2
8
7%; (iii) TPAP, NMO, CH Cl , r.t., 2 h, 84%; (iv) vinylmagnesium bromide, Et O, –78 °C to r.t., 89%; (v) Grubbs catalyst 12 (5 mol%),
2
2
2
CH Cl , r.t., 2 h, 79% for 13, 86% for 15; (vi) Ac O, DMAP, CH Cl , r.t., 0.5 h, 86% for 14, 88% for 16; (vii) Jones reagent, acetone, 0 °C, 5 h,
2
2
2
2
2
5
9% for 2, 56% for 3.
Whereas the gross structures of the series of compounds
3–16, 2 and 3 were easily secured, the stereochemistry at
5.95
H
6.01
H
1
the new stereocentre (C*OH or C*OAc) in these com-
pounds was correlated from chemical shift values based
3.36
Hb
HO2C
5.63
Hc
1.69
H
OAc
2
0,13
on precedence.
Thus, in compounds 15, 16 and 3, the
4
.31H
H
N
Ha
.55
methylene protons of the cyclopentene ring consistently
appeared at around d = 2.05 and 1.85 ppm, showing a
chemical shift difference of only 0.2 ppm, which is char-
acteristic for trans-3,5-disubstituted cyclopentenes.
Whereas, in the cis-series (13, 14 and 2), the same set of
protons showed a chemical shift difference of around
Boc
2
5
.07
Figure 2 NOESY correlations of compound 2
pentenylglycine derivatives having the natural S-
configuration at the a-amino centre.
0
.9 ppm. Moreover, NOESY studies on compound 2 re-
vealed correlations between protons at d = 2.55 and 3.36, Although the use of D-serine instead of L-serine as starting
2
.55 and 5.63 ppm, and between the geminal protons at material would deliver the desired configuration, we opt-
d = 2.55 and 1.69 ppm, as shown in Figure 2.
ed to use L-serine because of its lower price and ready
availability. Thus, the enantiomeric unsaturated ester ent-
Since the prepared cyclopentenylglycine derivatives 2
and 3 have R-configuration at the a-amino centre, we be-
came interested in extending this study to prepare cyclo-
4
was prepared from L-Boc-Ser-OMe (17) in a six-step se-
quence (Scheme 3) involving OTBS formation, reduction
of the ester functionality in the resulting 18 to the alcohol
OH
TBDMSO
BocHN
TBDMSO
TBDMSO
i
ii
iii
O
BocN
BocHN
iv
CO2Me
CO2Me
BocHN
vi
CH2OH
EtO2C
1
7
18
19
20
vii
HO
v
O
O
O
O
BocN
BocN
BocN
ent-4
21
22
H
+
H
EtO2C
steps
CO2H
CO2H
AcO
AcO
O
BocN
NHBoc
NHBoc
ent-2
ent-3
ent-7
Scheme 3 Reagents and conditions: (i) TBDMSCl, imidazole, CH Cl , 0 °C to r.t., 6 h, 96%; (ii) LiAlH , THF, 0 °C, 2 h, 61%; (iii) 2,2-
2
2
4
dimethoxypropane, p-TsOH (cat.), toluene, reflux, 1.5 h, 95%; (iv) TBAF, THF, 0 °C to r.t., 3 h, 90%; (v) oxalyl chloride, DMSO, NMM,
CH Cl , –78 °C to 0 °C, 1.5 h, 80%; (vi) (OEt) POCH CO Et, K CO , TBAI, H O, r.t., 24 h, 86%; (vii) vinylmagnesium bromide, CuI, TMSCl,
2
2
2
2
2
2
3
2
THF, –78 °C to r.t., 1 h, 82%.
©
Thieme Stuttgart · New York
Synthesis 2012, 44, 304–310

3
06
I. Kundu et al.
PAPER
1
9, simultaneous O,N-protection of the latter leading to leave a crude product that was purified by column chromatography
over silica gel (EtOAc–PE, 1:19) to provide the product 7.
the oxazolidine derivative 20, unmasking of the OTBS
2
5
protection, and subsequent oxidation of the resulting pri- Colourless liquid; yield: 147 mg (89%); [a]D –9.6 (c 0.48, CHCl3).
2
1
mary alcohol 21 leading to the (S)-Garner’s aldehyde 22,
IR (CHCl ): 2981, 1739, 1699, 1642, 1479, 1456, 1386, 1367, 1258,
3
1
–
and subsequent olefination with triethyl phosphonoace- 1176 cm .
tate, providing ent-4. The latter compound was obtained
1
H NMR (400 MHz, CDCl ): d = 5.71–5.68 (m, 1 H), 5.13–5.09 (m,
3
pure from a 19:1 crude mixture and showed spectroscopic
2
H), 4.14–4.08 (m, 2.5 H), 3.92 (d, J = 6.4 Hz, 1.5 H), 3.81 (d,
and optical properties similar to those reported.22 The J = 8.0 Hz, 1 H), 3.17–3.06 (m, 1 H), 2.52 (dd, J = 3.6, 14.8 Hz,
enantiomeric purity of compounds 4 and ent-4 were also 1 H), 2.35–2.26 (m, 1 H), 1.63–1.56 (s, 3 H), 1.49–1.47 (m, 12 H),
1
1
.23 (t, J = 6.8 Hz, 3 H).
determined by HPLC using a Chiralpak AD-H column
hexane–ethyl acetate, 95:5; flow rate 1 mL/min] and was
3
[
C NMR (100 MHz, CDCl ): d = 172.5, 152.9 (152.3), 137.5,
3
1
(
17.3 (117.0), 94.4 (93.3), 80.1, 64.6 (64.4), 60.3 (59.7), 42.9
found to be 98 and 96%, respectively. Conjugate addition
of vinyl cuprate to ent-4 then led to the desired product
ent-7 in a manner similar to that used for 7. From the con- Anal. Calcd for C17H29NO
jugate addition product ent-7, the enantiomeric cyclopen-
42.7), 35.1 (34.1), 28.4, 26.9 (26.2), 24.0 (22.6), 14.2.
: C, 62.36; H, 8.93; N, 4.28. Found: C,
5
6
2.57; H, 9.06; N, 4.20.
tenylglycine derivatives ent-2 and ent-3 were then MS (TOF, ES+): m/z (%) = 350 (100) [M + Na].
prepared by following the same steps detailed in
Scheme 1. Moreover, these compounds also displayed
spectral and optical properties that were in close agree-
ment with those observed for their enantiomers, thus indi- Colourless liquid; yield: 135 mg (82%); [a]
Compound ent-7
Prepared as described above from ent-4.
2
5
+8.9 (c 0.47, CHCl )
3
D
1
7b
[
Lit. +10 (c 2.2, CHCl )].
3
cating homogeneity.
In conclusion, we have developed a convenient route to
(
R)-tert-Butyl 4-[(R)-1-Hydroxypent-4-en-3-yl)-2,2-dimethyl-
four stereoisomeric 3¢-acetoxycyclopentenylglycine de- oxazolidine-3-carboxylate (8)
rivatives from a common source by using a standard set of A solution of 7 (300 mg, 0.92 mmol) in anhydrous Et
O (5 mL) was
2
added dropwise over 20 min to a suspension of LiAlH (52 mg, 1.38
reactions. The compounds prepared may find applications
as modified a-amino acids in the design and synthesis of
peptides, building blocks in organic synthesis, and as sub-
strates for use in biology. The methodology developed is
4
mmol) in anhydrous Et O (8 mL) at 0 °C under nitrogen. The reac-
2
tion mixture was allowed to come to r.t. and stirred for 1.5 h, then
cooled to 0 °C and slowly quenched with aq. NaOH (2.5 M, 2 mL).
The organic layer was separated and the thick aqueous layer was
short and efficient and should complement those existing triturated with Et O (20 mL). The combined organic extract was
2
in the literature. The approach may also find use in the washed successively with H O (2 × 25 mL) and brine (25 mL),
2
dried over Na SO , filtered and the filtrate was concentrated in vac-
uo to leave a crude product that was purified by column chromatog-
raphy over silica gel (EtOAc–PE, 1:3) to provide the product 8.
preparation of similar cyclopentenylglycine derivatives of
interest.
2
4
2
5
Viscous colourless liquid; yield: 260 mg (87%); [a] –35 (c 0.49,
D
Optical rotations were recorded in spectroscopic grade CHCl with
3
CHCl ).
3
a Rudolph Autopol IV polarimeter, [a] values are recorded in units
D
of 10–1 deg cm g . IR spectra were recorded with a Perkin–Elmer
2
–1
IR (CHCl ): 3437, 2979, 1699, 1479, 1456, 1392, 1367, 1256,
3
–
1
1
13
1175 cm .
Spectrum-1 spectrophotometer. H and C NMR spectra were re-
corded with a Bruker Avance-400 spectrometer purchased through
a DST-FIST grant. Data for rotamers are presented within parenthe-
ses wherever appropriate. Chemical shifts are recorded relative to
residual solvent peak. Mass spectra were recorded with a JEOL-
JMS 600 instrument (I. I. C. B., Kolkata or IACS, Kolkata). Chiral
HPLC studies were performed with an Agilent 1100 instrument as
a paid service from Chembiotek, Kolkata. Petroleum ether (PE) re-
fers to the fraction boiling in the range 60–80 °C. Silica gel (60–120
mesh) for column chromatography was purchased from Spectro-
chem, India.
1
H NMR (400 MHz, CDCl ): d = 5.68–5.65 (m, 1 H), 5.18–5.06 (m,
3
2
2
H), 3.94–3.82 (m, 3 H), 3.72–3.55 (m, 2 H), 2.61–2.59 (m, 1 H),
.18 (s, 1 H), 1.70–1.47 (m, 17 H).
1
3
C NMR (100 MHz, CDCl ): d = 152.9 (152.2), 139.1 (138.3),
3
1
17.4 (116.9), 94.2 (93.6), 80.1 (79.8), 65.3, 61.1 (60.7), 44.6
(
44.4), 32.9 (32.6), 28.3, 26.9 (26.3), 24.4 (22.8).
Anal. Calcd for C15 : C, 63.13; H, 9.54; N, 4.91. Found: C,
63.29; H, 9.76; N, 4.79.
H27NO
4
MS (TOF, ES+): m/z (%) = 308 (100) [M + Na].
(
R)-tert-Butyl 4-[(R)-1-Ethoxy-1-oxopent-4-en-3-yl]-2,2-di-
Compound ent-8
Prepared as described above from ent-7.
methyloxazolidine-3-carboxylate (7)
Vinylmagnesium bromide (6 mL, 6.0 mmol) was added dropwise to
a stirred suspension of CuI (572 mg, 3.0 mmol) in anhydrous THF
2
5
Colourless viscous liquid; yield: 246 mg (94%); [a] +34.0 (c 0.5,
D
CHCl ).
(
6 mL) at –5 °C under argon. After 15 min, the reaction mixture was
3
cooled to –78 °C and trimethylsilyl chloride (380 mL, 3 mmol) fol-
lowed by a solution of unsaturated ester 4 (150 mg, 0.5 mmol) in an-
hydrous THF (6 mL) were sequentially added dropwise over 15
min. The reaction mixture was allowed to come to r.t. and then
(
R)-tert-Butyl 2,2-Dimethyl-4-[(R)-1-oxopent-4-en-3-yl]oxazoli-
dine-3-carboxylate (9) and ent-9
TPAP (20 mg, 0.07 mmol, 10 mol%) and NMO (175 mg, 1.44
mmol) were added in single portions to a stirred suspension of alco-
hol 8 (200 mg, 0.72 mmol) and molecular sieves (4 Å, 250 mg) in
anhydrous CH Cl (20 mL). The reaction mixture was stirred for 2 h
and then diluted with anhydrous Et O (30 mL), filtered through
Celite and the filtrate was concentrated in vacuo to leave a crude
slowly quenched with sat. aq NH Cl (3 mL), extracted with EtOAc
4
(
2 × 25 mL) and the organic layer was washed successively with
sat. aq NH Cl (20 mL), H O (20 mL) and brine (20 mL), dried
2
2
4
2
(
Na SO ), filtered, and the filtrate was concentrated in vacuo to
2
2
4
Synthesis 2012, 44, 304–310
© Thieme Stuttgart · New York

PAPER
Stereoisomeric 3¢-Acetoxycyclopentenylglycine Derivatives
307
product that was purified by column chromatography over silica gel
EtOAc–PE, 1:9) to provide the product 9.
(m, 2 H), 3.89–3.83 (m, 2 H), 2.56 (s, 1 H), 1.77–1.70 (m, 2 H),
1.63 (merged singlets, 6 H), 1.47 (s, 9 H).
(
2
5
13
Colourless liquid; yield: 167 mg (84%); [a]
–12.6 (c 1.03,
C NMR (100 MHz, CDCl ): d = 151.6, 139.8, 138.9, 116.9
D
3
CHCl ).
(116.4), 115.5 (115.1), 93.7 (93.2), 79.6 (79.3), 71.7 (71.5), 64.7
(64.5), 60.2, 43.7, 36.7 (36.0), 27.9, 26.5 (25.8), 23.9 (22.2).
3
–
1
IR (CHCl ): 2980, 1728, 1697, 1388, 1367, 1258, 1175 cm .
3
1
Anal. Calcd for C17
H29NO : C, 65.57; H, 9.39; N, 4.50. Found: C,
4
H NMR (400 MHz, CDCl ): d = 9.69 (s, 1 H), 5.80–5.60 (m, 1 H),
3
6
5.75; H, 9.50; N, 4.44.
5
3
1
.14 (m, 2 H), 3.95–3.91 (m, 2 H), 3.80 (d, J = 8.4 Hz, 1 H), 3.40–
.20 (m, 1 H), 2.60 (d, J = 14 Hz, 1 H), 2.55–2.40 (m, 1 H), 1.58–
.47 (m, 15 H).
MS (TOF, ES+): m/z (%) = 334 (100) [M + Na].
1
3
Compound ent-10
Prepared as described above from ent-9.
Colourless viscous liquid; yield: 95 mg (43%); [a]D25 +28.00 (c
C NMR (100 MHz, CDCl ): d = 201.9 (201.4), 153.1, 137.3,
3
1
2
17.5, 94.6 (94.1), 80.5, 64.4 (59.7), 42.9 (42.6), 40.14, 29.7 (29.3),
8.4, 26.8 (26.2), 24.0 (22.5).
0
.10, CHCl3).
MS (TOF, ES+): m/z (%) = 284 (100) [M + H].
Compound ent-11
Prepared as described above from ent-9.
Compound ent-9
Prepared as described above from ent-8.
2
5
2
5
Colourless viscous liquid; yield: 88 mg (40%); [a]
D
+27.8 (c 0.66,
Colourless liquid; yield: 171 mg (86%); [a]D +11.2 (c 0.28,
CHCl ).
3
CHCl3).
(
R)-tert-Butyl 4-[(1R,4S)-4-Hydroxycyclopent-2-enyl]-2,2-di-
methyloxazolidine-3-carboxylate (13), (R)-tert-Butyl
-[(1R,4R)-4-Hydroxycyclopent-2-enyl]-2,2-dimethyloxazoli-
(
R)-tert-Butyl 4-[(3R,5S)-5-Hydroxyhepta-1,6-dien-3-yl]-2,2-
dimethyloxazolidine-3-carboxylate (10), (R)-tert-Butyl
-[(3R,5R)-5-Hydroxyhepta-1,6-dien-3-yl]-2,2-dimethyloxazo-
4
4
dine-3-carboxylate (15), ent-13 and ent-15
lidine-3-carboxylate (11), ent-10 and ent-11
Catalyst 12 (9 mg, 0.01 mmol, 5 mol%) was added to a stirred solu-
tion of diene 10 (68 mg, 0.22 mmol) in anhydrous and degassed
CH Cl (20 mL) under argon, and the homogeneous mixture was
stirred at r.t. for 2 h. The reaction mixture was then concentrated in
vacuo to leave a crude product that, on chromatography over silica
gel (EtOAc–PE, 1:5), provided the product 13. Cyclopentene deriv-
atives 15, ent-13 and ent-15 were prepared in a similar way.
Vinylmagnesium bromide (1 M in THF, 2 mL, 2 mmol) was added
dropwise to a stirred solution of aldehyde 9 (200 mg, 0.70 mmol) in
anhydrous Et O (12 mL) at –78 °C over 20 min. The reaction mix-
ture was stirred for 1 h at –78 °C, 2 h at –40 °C and then allowed to
come to r.t. and stirring was continued for 3 h. The reaction was
then cooled to –5 °C and slowly quenched with aq NaOH (1 N, 4
mL). The organic layer was separated and the thick aqueous layer
was triturated with EtOAc (25 mL). The combined organic extract
2
2
2
Compound 13
was washed successively with HCl (1 N, 10 mL), H O (10 mL) and
brine (10 mL), then dried (Na SO ), filtered and the filtrate was con-
2
25
Colourless liquid; yield: 49 mg (79%); [a]D –12.3 (c 0.52, CHCl3).
2
4
centrated in vacuo to leave a crude product that was purified by col-
umn chromatography over silica gel (EtOAc–PE, 1:9) to provided,
sequentially, the product 10 (101 mg, 46%) and 11 (96 mg, 43%) as
colourless viscous liquids in a combined yield of 89%. Compounds
ent-10 and ent-11 were prepared similarly.
IR (CHCl ): 3413, 2979, 2935, 2876, 1697, 1456, 1391, 1366, 1255,
1173, 1091 cm .
3
–
1
1
H NMR (300 MHz, CDCl ): d = 5.93–5.85 (m, 1 H), 5.87–5.82 (m,
3
1
H), 4.80 (br s, 1 H), 4.03–3.89 (m, 3 H), 3.83–3.80 (m, 1 H), 3.09
(
(
1
br s, 1 H), 2.39 (td, J = 8.1, 13.2 Hz, 1 H), 1.62–1.58 (m, 7 H), 1.48
m, 9 H).
Compound 10
3
25
C NMR (100 MHz, CDCl ): d = 152.0, 134.6 (134.3), 133.7, 93.2
[
a]D –30.7 (c 0.35, CHCl3).
3
(
92.8), 79.3 (78.9), 76.7, 64.8 (64.5), 59.6 (59.1), 46.7, 35.5 (35.1),
IR (CHCl ): 3468, 3078, 2980, 2933, 2343, 1698, 1686, 1643, 1479,
3
2
7.4, 26.2 (25.7), 23.3 (21.9).
–
1
1
456, 1392, 1367, 1256, 1175 cm .
MS (TOF, ES+): m/z (%) = 306 (100) [M + Na].
1
H NMR (400 MHz, CDCl ): d = 5.92–5.86 (m, 1 H), 5.84–5.69 (m,
3
1
1
1
H), 5.23 (d, J = 17.1 Hz, 1 H), 5.16–5.07 (m, 3 H), 4.13 (br s,
H), 3.94–3.89 (m, 2 H), 3.83 (br s, 2 H), 2.80 (br s, 1 H), 1.69–
.62 (merged singlets, 8 H), 1.47 (s, 9 H).
Compound 15
Prepared as described above from 11.
Colourless viscous liquid; yield: 53 mg (86%); [a]D25 +36.4 (c 0.24,
CHCl3).
1
3
C NMR (100 MHz, CDCl ): d = 152.9, 141.5 (141.4), 139.1
3
(
138.4), 117.7 (117.1), 114.2 (113.9), 94.2 (93.7), 80.1 (77.4), 70.5,
–
1
IR (CHCl ): 3429, 2979, 2932, 1695, 1388, 1366, 1255, 1173 cm .
6
2
5.4 (65.3), 60.6, 44.2 (43.6), 38.4 (37.1), 29.7 (28.4), 26.9 (26.3),
4.4 (22.8).
3
1
H NMR (400 MHz, CDCl ): d = 5.93–5.87 (m, 2 H), 4.90 (br s,
3
1
1
H), 3.95–3.80 (m, 2 H), 3.62 (d, J = 8.4 Hz, 1 H), 3.46–3.40 (m,
H), 2.06–2.02 (m, 1 H), 1.82 (ddd, J = 2.5, 8, 13.5 Hz, 1 H), 1.62
Anal. Calcd for C H NO : C, 65.57; H, 9.39; N, 4.50. Found: C,
17
29
4
6
5.69; H, 9.56; N, 4.39.
(
s, 3 H), 1.49–1.45 (m, 13 H).
MS (TOF, ES+): m/z (%) = 334 (100) [M + Na].
1
3
C NMR (100 MHz, CDCl ): d = 152.8 (152.1), 136.9, 134.7
3
(
134.2), 94.3 (93.8), 80.2 (79.9), 65.7 (65.2), 60.4 (60.2), 48.1
Compound 11
25
(47.8), 36.3 (36.2), 28.3, 27.4 (26.7), 22.9 (22.6).
[
a]D –29.0 (c 0.35, CHCl3).
MS (TOF, ES+): m/z (%) = 306 (100) [M + Na].
IR (CHCl ): 3435, 3079, 2980, 2935, 2343, 1698, 1642, 1478, 1456,
3
–
1
1
392, 1367, 1256, 1175, 1093 cm .
Compound ent-13
Prepared as described above from ent-10.
1
H NMR (300 MHz, CDCl ): d = 5.84–5.73 (m, 2 H), 5.22 (d,
3
J = 17.1 Hz, 1 H), 5.15–5.05 (m, 3 H), 4.13 (br s, 1 H), 3.94–3.91
2
5
Colourless viscous liquid; yield: 46 mg (75%); [a] +11.7 (c 0.67,
D
CHCl ).
3
©
Thieme Stuttgart · New York
Synthesis 2012, 44, 304–310

3
08
I. Kundu et al.
PAPER
(R)-2-[(1R,4S)-4-Acetoxycyclopent-2-enyl]-2-(tert-butoxycar-
Compound ent-15
bonylamino)acetic Acid (2), (R)-2-[(1R,4R)-4-Acetoxycyclo-
pent-2-enyl]-2-(tert-butoxycarbonylamino)acetic Acid (3), ent-2
and ent-3
Prepared as described above from ent-11.
2
5
Colourless viscous liquid; yield: 56 mg (90%); [a] –37.5 (c 0.3,
D
CHCl ).
3
Jones reagent (2.67 M, 100 mL, 0.18 mmol) was added to a solution
of oxazolidine derivative 14 (40 mg, 0.12 mmol) in acetone (2.5
mL) at 0 °C. The reaction mixture was stirred for 5 h and then
quenched by adding 2-propanol (200 mL). The reaction mixture was
(
R)-tert-Butyl 4-[(1R,4S)-4-Acetoxycyclopent-2-enyl]-2,2-di-
methyloxazolidine-3-carboxylate (14), (R)-tert-Butyl
-[(1R,4R)-4-Acetoxycyclopent-2-enyl]-2,2-dimethyloxazoli-
4
stirred for 15 min, then neutralized with sat. aq NaHCO to pH 4–5
3
dine-3-carboxylate (16), ent-14 and ent-16
and extracted with EtOAc (2 × 15 mL). The combined organic ex-
Ac O (0.1 mL, excess) and DMAP (5 mg) were added to a stirred
2
tract was washed with H O (20 mL), brine (15 mL), dried over
2
solution of alcohol 13 (60 mg, 0.22 mmol) in anhydrous CH Cl (3
mL). The reaction mixture was stirred for 10 h at r.t. and then
2
2
Na SO , then filtered and the filtrate was concentrated in vacuo to
2
4
leave a crude product that, on column chromatography over silica
gel (EtOAc–PE, 4:1), provided product 2. Carboxylic acids 3, ent-2
and ent-3 were prepared similarly.
poured into ice-cooled H O (10 mL) while stirring for 30 min. The
2
aqueous layer was extracted with CH Cl (2 × 10 mL) and the com-
2
2
bined organic extract was washed with H O (2 × 10 mL), brine (10
2
mL), then dried over Na SO , filtered and the filtrate was concen-
2
4
Compound 2
Colourless liquid; yield: 23 mg (59%); [a]
MeOH).
trated in vacuo to leave a crude product that, on column chromatog-
raphy over silica gel (EtOAc–PE, 1:9), provided the product 14. The
acetate derivatives 16, ent-14 and ent-16 were prepared similarly.
2
5
+15.7 (c 0.27,
D
IR (CHCl ): 3436, 2927, 2854, 1715, 1514, 1393, 1368, 1245, 1164,
3
–
1
Compound 14
1023 cm .
2
5
Colourless liquid; yield: 56 mg (86%); [a]D –37.8 (c 1.08, CHCl3).
1
H NMR (400 MHz, CDCl ): d = 6.01 (d, J = 4.8 Hz, 1 H), 5.95 (d,
3
IR (CHCl ): 2979, 2935, 2877, 1736, 1697, 1387, 1377, 1366, 1243,
J = 5.2 Hz, 1 H), 5.63 (d, J = 6 Hz, 1 H), 5.07 (d, J = 6.8 Hz, 1 H),
4.32–4.30 (m, 1 H), 3.37–3.35 (m, 1 H), 2.55 (dt, J = 14.4, 6.8 Hz,
1 H), 2.07 (s, 3 H), 1.69 (d, J = 14.4 Hz, 1 H), 1.45 (s, 9 H).
3
1
–
1
085 cm .
1
H NMR (400 MHz, CDCl ): d = 5.90–5.86 (m, 2 H), 5.64 (br s,
3
1
3
1
H), 4.04–3.77 (m, 3 H), 3.28–3.12 (m, 1 H), 2.42 (dt, J = 8.4,
C NMR (100 MHz, CDCl ): d = 173.6, 169.9, 155.2, 134.1, 132.3,
3
1
3.2 Hz, 1 H), 2.04 (s, 3 H), 1.68–1.47 (m, 16 H).
79.4, 77.7, 55.1, 44.7, 32.0, 27.3, 20.2.
1
3
HRMS (TOF, ES+): m/z [M+ + Na] calcd for C H NO Na:
322.1267; found: 322.1264.
C NMR (400 MHz, CDCl ): d = 169.9, 151.1, 137.2 (136.9),
3
14 21
6
1
4
29.6, 93.2 (92.7), 79.3 (78.9), 78.4 (78.2), 64.4 (63.5), 58.8 (58.6),
6.8 (46.1), 31.4 (30.9), 27.4, 26.3 (25.8), 23.2 (21.9), 20.2.
Compound 3
Prepared as described above from 16.
Anal. Calcd for C H NO : C, 62.75; H, 8.36; N, 4.30. Found: C,
17
27
5
6
2.88; H, 8.47; N, 4.21.
2
5
Colourless viscous liquid; yield: 21 mg (56%); [a] +19.6 (c 0.41,
MeOH).
D
MS (TOF, ES+): m/z (%) = 348 (100) [M + Na].
Compound 16
Prepared as described above from 15.
IR (CHCl ): 3437, 2918, 2850, 1711, 1499, 1393, 1368, 1247, 1164,
1022 cm .
3
1
–
2
5
1
Colourless viscous liquid; yield: 61 mg (88%); [a]D +72.0 (c 0.44,
H NMR (400 MHz, CDCl ): d = 6.04 (br s, 1 H), 5.93 (br s, 1 H),
3
CHCl3).
5.71 (br s, 1 H), 4.80 (d, J = 8.4 Hz, 1 H), 4.42–4.39 (m, 1 H), 3.54
(
br s, 1 H), 2.19–2.17 (m, 1 H), 2.07–2.03 (merged singlet, 4 H),
IR (CHCl ): 2979, 2935, 2876, 1736, 1697, 1387, 1376, 1365, 1243,
3
1
–
1.45 (s, 9 H).
13C NMR (100 MHz, CDCl
8
1
090 cm .
1
3
): d = 174.6, 171.0, 156.0, 135.3, 133.4,
H NMR (400 MHz, CDCl ): d = 6.01 (d, J = 5.2 Hz, 1 H), 5.91–
3
0.6, 79.4, 55.0, 46.8, 33.5, 29.7, 21.1.
5
.89 (m, 1 H), 5.71 (br s, 1 H), 3.97–3.80 (m, 2 H), 3.63 (d,
J = 9.2 Hz, 1 H), 3.45–3.36 (m, 1 H), 2.08–2.02 (merged singlets,
HRMS (TOF, ES+): m/z [M+ + Na] calcd for C H NO Na:
1
4
21
6
4
1
H), 1.93 (ddd, J = 1.6, 7.6, 14.4 Hz, 1 H), 1.63 (1.57) (s, 3 H),
.49–1.47 (m, 12 H).
322.1267; found: 322.1253.
1
3
Compound ent-2
Prepared as described above from ent-14.
C NMR (100 MHz, CDCl ): d = 170.9, 152.8 (152.1), 139.9,
3
1
30.1, 94.3 (93.8), 80.3, 79.9, 65.8 (65.2), 60.0, 48.3 (47.9), 33.1
2
5
(
32.9), 28.4 (29.7), 27.4 (26.8), 24.3 (22.9), 21.3.
Colourless viscous liquid; yield: 20 mg (55%); [a]
–14.82 (c
D
0
.35, MeOH).
Anal. Calcd for C H NO : C, 62.75; H, 8.36; N, 4.30. Found: C,
17
27
5
6
2.93; H, 8.49; N, 4.37.
Compound ent-3
Prepared as described above from ent-16.
MS (TOF, ES+): m/z (%) = 348 (100) [M + Na].
2
5
Colourless viscous liquid; yield: 21 mg (57%); [a]D –20.62 (c
Compound ent-14
Prepared as described above from ent-13.
0
.11, MeOH).
2
5
Colourless viscous liquid; yield: 62 mg (90%); [a] +39.5 (c 0.42,
D
(S)-Methyl 2-(tert-Butoxycarbonylamino)-3-(tert-butyldimeth-
ylsilyloxy)propanoate (18)
CHCl ).
3
A solution of TBDMSCl (0.9 g, 6 mmol) in CH Cl (10 mL) was
added dropwise at 0 °C to a stirred solution of (S)-methyl L-Boc-
2
2
Compound ent-16
Prepared as described above from ent-15.
Ser-OH (1.1 g, 5 mmol) and imidazole (0.410 g, 6 mmol) in CH Cl
2
2
2
5
(10 mL). The resulting solution was allowed to come to r.t. and
stirred overnight. The reaction mixture was poured into aq HCl
Colourless viscous liquid; yield: 63 mg (91%); [a]D –76.5 (c 0.81,
CHCl3).
(
1 N, 50 mL) and extracted with CH Cl (2 × 50 mL). The com-
2
2
Synthesis 2012, 44, 304–310
© Thieme Stuttgart · New York

PAPER
Stereoisomeric 3¢-Acetoxycyclopentenylglycine Derivatives
309
bined organic layer was washed with aq HCl (1 N, 50 mL), H O (50
MS (TOF, ES+): m/z (%) = 346 (100) [M + H].
2
mL), brine (50 mL), dried (Na SO ), then filtered and the filtrate
2
4
was concentrated in vacuo to leave a crude oily liquid that was pu-
rified by chromatography over silica gel (EtOAc–PE, 1:19) to pro-
vide the product.
(S)-tert-Butyl 4-(Hydroxymethyl)-2,2-dimethyloxazolidine-3-
carboxylate (21)
A solution of TBAF (1.43 g, 5.5 mmol) in THF (7 mL) was added
dropwise to a stirred solution of 20 (1.72 g, 5 mmol) in THF (24
mL) at 0 °C. The resulting solution was stirred at r.t. for 2 h, then
concentrated in vacuo to leave a crude mass, which was extracted
2
5
Colourless liquid; yield: 1.60 g (96%); [a]D +18.1 (c 0.90, CHCl3).
–
1
IR (neat): 3452, 2956, 2859, 1721, 1503 cm .
1
with EtOAc (2 × 50 mL). The organic extract was washed with H O
H NMR (CDCl , 400 MHz): d = 5.32 (d, J = 8.4 Hz, 1 H), 4.33 (td,
2
3
(
100 mL), brine (100 mL), dried (Na SO ), then filtered and the fil-
J = 6, 2.8 Hz, 1 H), 4.02 (dd, J = 10, 2.4 Hz, 1 H), 3.79 (dd, J = 10,
2 4
trate was concentrated in vacuo to leave a crude mass that was pu-
rified by chromatography over silica gel (EtOAc–PE, 4:6) to
provide the product.
2
–
.8 Hz, 1 H), 3.72 (s, 3 H), 1.44 (s, 9 H), 0.84 (s, 9 H), 0.01 (s, 3 H),
0.01 (s, 3 H).
1
3
C NMR (CDCl , 100 MHz): d = 171.2, 155.4, 79.8, 63.7, 55.6,
3
2
5
Colourless liquid; yield: 1.04 g (90%); [a]
D
+20.9 (c 0.73, CHCl3)
5
2.2, 28.3, 25.7, 18.1, –5.6, –5.7.
2
1b
[
Lit. +21.8 (c 3.85, CHCl )].
3
Anal. Calcd for C H NO Si: C, 54.02; H, 9.37; N, 4.20. Found: C,
5
15
31
5
–
1
IR (neat): 3446, 1702, 1459, 1393, 1368 cm .
4.12; H, 9.31; N, 4.25.
1
H NMR (CDCl , 400 MHz): d = 4.04–3.90 (m, 2 H), 3.67 (t,
MS (TOF, ES+): m/z (%) = 334 (100) [M + H].
3
J = 8 Hz, 2 H), 3.52 (d, J = 6.8 Hz, 1 H), 2.71 (br s, 1 H), 1.46–1.36
(
13
m, 15 H).
(
R)-tert-Butyl 1-(tert-Butyldimethylsilyloxy)-3-hydroxypropan-
-ylcarbamate (19)
2
C NMR (CDCl , 100 MHz): d = 152.4, 94.1, 81.2, 65.3, 59.5, 28.4,
7.1, 24.6.
3
A solution of 18 (1.66 g, 5 mmol) in THF (12 mL) was added drop-
2
wise to a stirred suspension of LiAlH (285 mg, 7.5 mmol) in THF
(
4
MS (TOF, ES+): m/z (%) = 232 (100) [M + H].
12 mL) at 0 °C, and the resulting solution was stirred at the same
temperature for 1.5 h under nitrogen. The reaction was quenched by
dropwise addition of aq KOH (1 N, 2 mL) until a white precipitate
appeared. The reaction mixture was extracted with EtOAc (2 × 50
(
(
R)-tert-Butyl 4-Formyl-2,2-dimethyloxazolidine-3-carboxylate
22)
A solution of DMSO (2.1 mL, 28.5 mmol) in anhydrous CH Cl (3
2
2
mL) and the combined organic layer was washed with H O (2 × 50
2
mL) was added dropwise to a stirred solution of oxalyl chloride
1.04 mL, 12 mmol) in CH Cl (20 mL) at –78 °C. The reaction was
mL), brine (50 mL), dried (Na SO ), filtered and the filtrate was
2
4
(
2
2
concentrated in vacuo to leave a crude viscous mass that was puri-
fied by chromatography over silica gel (EtOAc–PE, 2:8) to provide
the product.
Colourless liquid; yield: 930 mg (61%); [a]D25 +14.4 (c 1.52,
stirred for 20 min at the same temperature, then a solution of alcohol
2
1 (2.31 g, 10 mmol) in CH Cl (15 mL) was added dropwise to the
2
2
above mixture and stirring was continued at –78 °C for 35 min. A
solution of NMM (5.9 mL, 53.7 mmol) in CH Cl (6 mL) was added
to the reaction mixture, which was allowed to come to 0 °C and
stirred vigorously for 5 min before being poured into cold aq HCl
2
2
CHCl3).
–
1
IR (neat): 3450, 2956, 2932, 1695, 1504 cm .
(
1 N, 50 mL). The mixture was extracted with CH Cl (2 × 50 mL)
1
2
2
H NMR (CDCl , 400 MHz): d = 5.02 (br s, 1 H), 3.77–3.71 (m,
3
and the combined organic layer was washed with H O (2 × 50 mL),
brine (2 × 50 mL), dried (Na SO ), filtered and the filtrate was con-
2
3
9
H), 3.63–3.59 (m, 2 H), 2.74 (br s, 1 H), 1.38 (s, 9 H), 0.82 (s,
H), 0.2 (s, 6 H).
2
4
centrated in vacuo to leave a pale-yellow crude product that was pu-
rified by chromatography over silica gel (EtOAc–PE, 1:9) to
provide the product.
1
3
C NMR (CDCl , 100 MHz): d = 156.0, 79.5, 63.7, 52.6, 28.4, 25.8,
3
1
8.2, –3.6, –5.6.
2
5
Anal. Calcd for C H NO Si: C, 55.04; H, 10.23; N, 4.59. Found:
C, 55.14; H, 10.18; N, 4.66.
Colourless liquid; yield: 1.84 g (80%); [a] +99.2 (c 1.01, CHCl3)
1
4
31
4
D
2
1
[Lit. +105 (c 1.4, CHCl )].
3
MS (TOF, ES+): m/z (%) = 306 (100) [M + H].
IR (neat): 2981, 2933, 1741, 1709, 1479, 1459, 1393, 1380, 1368
cm .
–
1
(
R)-tert-Butyl 4-[(tert-Butyldimethylsilyloxy)methyl]-2,2-di-
1
H NMR (CDCl , 400 MHz): d = 9.55 (9.61) (s, 1 H), 4.36–4.19 (m,
3
methyloxazolidine-3-carboxylate (20)
p-TsOH (~5 mg) was added to a solution of 19 (1.52 g, 5 mmol) and
2
the resulting solution was heated to reflux under nitrogen for 1.5 h.
The reaction was then allowed to cool to r.t., concentrated in vacuo
and the residual crude mass was purified by chromatography over
silica gel (EtOAc–PE, 1:9) to provide the product.
1
1
H), 4.13–4.04 (m, 2 H), 1.52–1.50 (s, 9 H), 1.44 (s, 6 H).
3
C NMR (CDCl , 100 MHz): d = 199.3 (199.4), 151.2 (152.5), 95.0
,2-dimethoxy propane (2.1 mL, 17 mmol) in toluene (25 mL) and
3
(
2
94.3), 80.9 (81.2), 64.6 (64.7), 63.8 (63.3), 28.2 (28.1), 25.7 (26.6),
3.7 (24.6).
MS (TOF, ES+): m/z (%) = 230 (100) [M + H].
2
5
(S,E)-tert-Butyl 4-(3-Ethoxy-3-oxoprop-1-enyl)-2,2-dimethyl-
oxazolidine-3-carboxylate (ent-4)
Colourless liquid; yield: 1.64 g (95%); [a]D +26.2 (c 1.77, CHCl3).
–
1
IR (neat): 2957, 2932, 1704, 1473, 1389 cm .
A mixture of aldehyde 22 (1.60 g, 7 mmol), TBAI (262 mg, 0.71
mmol), triethyl phosphonoacetate (2.86 mL, 14 mmol) and aq
K CO (3 M, 4.8 mL) was stirred vigorously at r.t. for 12 h, then ex-
1
H NMR (CDCl , 400 MHz): d = 3.97 (t, J = 8 Hz, 1 H), 3.86–3.82
m, 1.5 H), 3.76–3.64 (m, 1.5 H), 3.44–3.32 (m, 1 H), 1.42 (s, 9 H),
3
(
2
3
0
.83 (s, 9 H), 0.00 (s, 6 H).
tracted with hexane (2 × 50 mL) and the combined extract was
1
3
washed with H O (2 × 50 mL) and brine (50 mL). The organic ex-
2
C NMR (CDCl , 100 MHz): d = 152.2 (151.8), (93.8) 93.3, 79.6
3
tract was then dried (Na SO ), filtered and the filtrate was concen-
2
4
(80.0), 65.0 (64.8), 62.1 (61.3), 58.4 (58.5), 28.5 (28.4), 26.7 (27.3),
trated in vacuo to leave a pale-yellow crude product that was
purified by chromatography over silica gel (EtOAc–PE, 1:19) to
provide the product.
2
5.8, 23.1 (24.5), 18.2.
Anal. Calcd for C H NO Si: C, 59.09; H, 10.21; N, 4.05. Found:
C, 59.23; H, 10.35; N, 4.21.
1
7
35
4
©
Thieme Stuttgart · New York
Synthesis 2012, 44, 304–310

3
10
I. Kundu et al.
PAPER
2
5
Colourless solid; yield: 1.80 g (86%); mp 46–48 °C; [a] +65.7 (c
Nahrstedt, A.; Jaroszewski, J. W. Biochem. Syst. Ecol. 2001,
29, 219. (d) Tober, I.; Conn, E. E. Phytochemistry 1985, 24,
1215. (e) Cramer, U.; Rehfeldt, A. G.; Spener, F.
Biochemistry 1980, 19, 3074.
D
22
0
.4, CHCl ) [Lit. +66 (c 0.3, CHCl )].
3 3
–
1
IR (neat): 2987, 1718, 1702, 1662, 1379, 1367 cm .
1
H NMR (CDCl , 400 MHz): d = 6.85–6.80 (m, 1 H), 5.94 (5.89) (d,
J = 16.0 Hz, 1 H), 5.56–4.41 (m, 1 H), 4.22–4.19 (m, 2 H), 4.09
dd, J = 9.2, 6.8 Hz, 1 H), 3.80 (dd, J = 9.2, 2.4 Hz, 1 H), 1.64–1.42
3
(7) Santoso, S.; Kemmer, T.; Trowitzsch, W. Liebigs Ann.
Chem. 1981, 658.
8) Nyeki, O.; Szalay, K. S.; Kisfaludy, L.; Karpati, E.; Szporny,
(
(
1
(
m, 15 H), 1.30 (app. t, 3 H).
L.; Makara, G. B.; Varga, B. J. Med. Chem. 1987, 30, 1719.
3
(9) Chand, P.; Babu, Y. S.; Bantia, S.; Rowland, S.; Dehghani,
A.; Kotian, P. L.; Hutchison, T. L.; Ali, S.; Brouillette, W.;
El-Kattan, Y.; Lin, T.-H. J. Med. Chem. 2004, 47, 1919.
10) Ashton, W. T.; Dong, H.; Sisco, R. M.; Doss, G. A.; Leiting,
B.; Patel, R. A.; Wu, J. K.; Marsilio, F.; Thornberry, N. A.;
Weber, A. E. Bioorg. Med. Chem. Lett. 2004, 14, 859.
11) (a) Gelmi, M. L.; Clerici, F.; Gandolfi, R.; Pellegrino, S.
Tetrahedron: Asymmetry 2008, 19, 584. (b) Pellegrino, S.;
Ferri, N.; Colombo, N.; Cremona, E.; Corsini, A.; Fanelli,
R.; Gelmi, M. L.; Cabrele, C. Bioorg. Med. Chem. Lett.
2009, 19, 6298. (c) Cabrele, C.; Clerici, F.; Gandolfi, R.;
Gelmi, M. L.; Molinari, F.; Pellegrino, S. Tetrahedron 2006,
C NMR (CDCl , 100 MHz): d = 166.0, 151.5 (152.0), 145.9
145.7), 122.2, 94.4 (93.9), 80.1 (80.6), 67.3 (67.1), 67.3 (67.1),
3
(
5
7.9, 28.3, 26.4 (27.2), 23.5 (24.6), 14.2.
(
(
MS (TOF, ES+): m/z (%) = 300 (100) [M + H].
Acknowledgment
Financial assistance from DST, New Delhi (Grant No. SR/S1/OC-
5/2009), is gratefully acknowledged. We are also thankful to CSIR
3
and UGC (New Delhi) for fellowships.
6
2, 3502. (d) Pellegrino, S.; Clerici, F.; Gelmi, M. L.
References
Tetrahedron 2008, 64, 5657. (e) Surman, M. D.; Miller, M.
J. Org. Lett. 2001, 3, 519. (f) Bailey, P. D.; Rosair, G. M.;
Taylor, D.; McDonald, I. M. Chem. Commun. 2000, 2451.
12) (a) Aggarwal, V. K.; Monteiro, N.; Tarver, G. J.; Lindell, S.
D. J. Org. Chem. 1996, 61, 1192. (b) Ward, S. E.; Holmes,
A. B.; McCague, R. J. Chem. Soc., Chem. Commun. 1997,
(
1) (a) Barrett, G. C. Amino Acids, Peptides and Proteins, Vol.
2; The Chemical Society: London, 2001. (b) Park, K.-H.;
3
(
Kurth, M. J. Tetrahedron 2002, 58, 8629. (c) Jackson, R. F.
W. In Asymmetric Synthesis and Application of Alpha-
Amino Acids; Soloshonok, V. A.; Izawa, K., Eds.; American
Chemical Society: Washington DC, 2009, 2. (d)Grauer, A.;
König, B. Eur. J. Org. Chem. 2009, 5099. (e) Soloshonok,
V. A.; Sorochinsky, A. E. Synthesis 2010, 2319.
2085. (c) Li, F.; Brogan, J. B.; Gage, J. L.; Zhang, D.; Miller,
M. J. J. Org. Chem. 2004, 69, 4538. (d) Koester, D. C.;
Holkenbrink, A.; Werz, D. B. Synthesis 2010, 3217.
(
(
13) Lee, Y. J.; Schiffer, G.; Jäger, V. Org. Lett. 2005, 7, 2317.
14) (a) Bandyopadhyay, A.; Pahari, A. K.; Chattopadhyay, S. K.
Tetrahedron Lett. 2009, 50, 6036. (b) Sarkar, K.; Singha, S.
K.; Chattopadhyay, S. K. Tetrahedron: Asymmetry 2009, 20,
(
(
2) (a) Hazelard, D.; Fedel, A.; Guillot, R. Tetrahedron:
Asymmetry 2008, 19, 2063. (b) Yamashita, D. S.; Dodds, R.
A. Curr. Pharm. Des. 2000, 6, 1. (c) Klein, S. I.; Molino, B.
F.; Czekaj, M.; Gardner, C. J.; Chu, V.; Brown, K.; Sabatino,
R. D.; Bostwick, J. S.; Kasiewski, C.; Bentley, R.; Windisch,
V.; Perrone, M.; Dunwiddie, C. T.; Leadly, R. J. J. Med.
Chem. 1998, 41, 2492.
1719. (c) Chattopadhyay, S. K.; Biswas, T.; Biswas, T.
Tetrahedron Lett. 2008, 49, 1365. (d) Bandyopadhyay, A.;
Pal, B. K.; Chattopadhyay, S. K. Tetrahedron: Asymmetry
2
008, 19, 1875. (e) Chattopadhyay, S. K.; Sarkar, K.;
Thander, L.; Roy, S. P. Tetrahedron Lett. 2007, 48, 6113.
f) Chattopadhyay, S. K.; Sarkar, K.; Karmakar, S. Synlett
005, 2083.
3) For reviews, see: (a) Zhang, D. Curr. Pharm. Des. 1999, 5,
73. (b) Knapp, S. Chem. Rev. 1995, 95, 1859. For some
(
2
leading references, see: (c) Pohlman, M.; Kazmaier, U. Org.
Lett. 2003, 5, 2631. (d) Huang, T.; Keh, C. C. K.; Li, C.-J.
Chem. Commun. 2002, 2440. (e) O’Donnell, M. J.; Drew,
M. D.; Cooper, J. T.; Delgado, F.; Zhou, C. J. Am. Chem.
Soc. 2002, 124, 9348. (f) Avenazo, A.; Busto, J. H.; Canal,
N.; Peregrina, J. M. Chem. Commun. 2003, 1376. (g) Jones,
R. C. F.; Bethelot, D. J. C.; Iley, J. N. Chem. Commun. 2000,
(
(
15) Thander, L.; Sarkar, K.; Chattopadhyay, S. K. Tetrahedron:
Asymmetry 2009, 20, 1213.
16) Jako, I.; Uiber, P.; Mann, A.; Wermuth, C. G.; Boulanger,
T.; Norberg, B.; Evrard, G.; Durrant, F. J. Org. Chem. 1991,
5
6, 5729.
17) (a) Hanessian, S.; Sumi, K. Synthesis 1991, 1083.
b) Flamant-Robin, C.; Wang, Q.; Chiaroni, A.; Sasaki, N.
(
2
131.
4) (a) Singh, S.; Pennington, M. W. Tetrahedron Lett. 2003, 44,
683. (b) Venkatraman, S.; Njoroge, F. G.; Girijavallabhan,
V.; McPhail, A. T. J. Org. Chem. 2002, 67, 2686.
c) Alonso, D. A.; Bertilsson, S. K.; Johnsson, S. Y.; Nordin,
S. J. M.; Södergren, M. J.; Andersson, P. G. J. Org. Chem.
999, 64, 2276.
5) (a) Andersen, L.; Nielson, B.; Jaroszewski, J. W. Chirality
000, 12, 665. (b) Katagiri, N.; Okada, M.; Morishita, Y.;
Kaneko, C. J. Chem. Soc., Chem. Commun. 1996, 2137.
c) Bourgeois-Cury, A.; Doan, D.; Gore, J. Tetrahedron Lett.
992, 33, 1277. (d) Bartlett, P. A.; Barstow, J. F. J. Org.
(
(
(
(
A. Tetrahedron 2002, 58, 10475.
2
(
18) For some recent reviews, see: (a) Grubbs, R. H.; Schrock, R.
R.; Furstner, A. Adv. Synth. Catal. 2007, 349, 1.
(
(
b) Metathesis in Natural Product Synthesis; Cossy, J.;
Arsencyalis, S.; Mayer, C., Eds.; Wiley-VCH: Weinheim,
010. (c) Chattopadhyay, S. K.; Karmakar, S.; Biswas, T.;
Majumdar, K. C.; Rahaman, H.; Roy, B. Tetrahedron 2007,
3, 3919.
19) Brown, H. C.; Garg, C. P.; Liu, K.-T. J. Org. Chem. 1971,
6, 387.
20) (a) Trost, B. M.; Verhoeven, T. R. J. Am. Chem. Soc. 1980,
02, 4730. (b) Kobayashi, Y.; Ito, M.; Igarashi, J.
1
2
2
6
(
(
(
1
3
Chem. 1982, 47, 3933.
6) (a) Rinner, U.; Lentsch, C.; Aichinger, C. Synthesis 2010,
1
Tetrahedron Lett. 2002, 43, 4829. (c) De Clercq, P.;
Van Haver, D.; Vandewalle, M. Tetrahedron 1974, 30, 55.
21) (a) Garner, P.; Park, J. M. Org. Synth. 1991, 70, 18.
3763. (b) Clausen, V.; Frydenvang, K.; Koopmann, R.;
Jørgensen, L. B.; Abbiw, D. K.; Ekpe, P.; Jaroszewski, J. W.
J. Nat. Prod. 2002, 65, 542. (c) Andersen, L.; Clausen, V.;
Oketch-Rabah, H. A.; Lechtenberg, M.; Adsersen, A.;
(
(
(
b) Avenoza, A.; Cativiela, C.; Corzana, F.; Peregrina, J. M.;
Zurbano, M. M. Synthesis 1997, 1146.
22) (a) Dondoni, A.; Merino, P.; Perrone, D. Tetrahedron 1993,
49, 2939. (b) Devel, L.; Vidal-Cros, A.; Thellend, A.
Tetrahedron Lett. 2000, 41, 299.
Synthesis 2012, 44, 304–310
© Thieme Stuttgart · New York