O-Dichlorovinyl Osides: A New Anomeric Protecting Group

Article abstract of DOI:10.1055/s-2003-42487

Dichlorovinyl glycopyranosides are obtained from peracetylated glycopyranoses by a Wittig-type reaction with Ph₃P/CCl₄ on anomeric acetate. This new type of glycosides has been used to get rapid access to the corresponding perbenzylated glycopyranoses.

Full text of DOI:10.1055/s-2003-42487

PAPER
2831
O-Dichlorovinyl Osides: A New Anomeric Protecting Group
O-Dichlorovinyl
eO
sides nata M. de Figueiredo,a Vincent Bailliez,a Didier Dubreuil,b Alain Olesker,a Jeannine Cleophax*a
a
Institut de Chimie des Substances Naturelles du C.N.R.S., Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
Fax +33(1)69077247; E-mail: Jeannine.Cleophax@icsn.cnrs-gif.fr
b
Laboratoire de Synthèse Organique associé au CNRS, UMR 6513, Faculté des Sciences et des Techniques, 2, rue de la Houssinière,
BP 92208, 44322 Nantes Cedex 3, France
Received 29 September 2003; revised 9 October 2003
conditions,4 with the exception of deoxylactones where
the primary acetate can also be partially transformed into
dichlorovinyl ether group.4b,c
Abstract: Dichlorovinyl glycopyranosides are obtained from per-
acetylated glycopyranoses by a Wittig-type reaction with Ph3P/CCl4
on anomeric acetate. This new type of glycosides has been used to
get rapid access to the corresponding perbenzylated glycopyra-
noses.
We have attempted the reaction of Ph3P/CCl4 complex in
concentrated media on easily accessible peracetylated -
and -hexopyranoses 1a–e. In these conditions, the ano-
meric acetate underwent the Wittig-like reaction, leading
to the selective formation of tetra-O-acetyl dichlorovinyl
ethers 2a–e (Scheme 1). The reaction occurred in good
yield under microwave activation (10 min) or classical
heating (50 min) with retention of the anomeric configu-
ration (Table 1).
Key words: glycosides, Wittig-type reactions, regioselectivity, mi-
crowave irradiation
The role of carbohydrates in diverse biological complex
structures is well established.1 Many cellular processes
are regulated through interactions between macromole-
cules, some of them containing carbohydrates as mono-
mers or oligomers. Due to their biological importance,
access to small oligosaccharides by chemical synthesis
continues to be the subject of the main efforts in research
groups.2 Partially or fully benzylated hexoses are key in-
termediates for the elaboration of di- or polysaccharides in
glycosidation processes. An usual way for the preparation
of these protected hexoses required preliminary protec-
tion of the anomeric position, mainly achieved as methyl
or allyl glycosides. Regeneration of the anomeric position
from small pyranoside intermediates is well documented
but often remains a limiting step for the preparation of
more complex derivatives. In this paper, we describe the
synthesis of a novel anomeric protecting group of pyra-
noses that represents an attractive alternative for glyco-
side synthesis. The efficiency of the procedure is
illustrated by the easy preparation of perbenzylated hex-
oses.
Peracetylated sugars are the substrate of choice in these
reactions. As a matter of fact, the perpropionylated -D-
glucopyranose was converted into the corresponding tet-
ra-O-propionyl dichlorovinyl ether under similar condi-
tions in 30% yield. The perbenzoylated
-D-
glucopyranose and the acetyl 2,3,4,6-tetra-O-benzyl -D-
glucopyranose remained unchanged during the same pro-
cess.
A base catalyzed deacetylation (NaOMe, MeOH) of the
hexosides 2a–e furnished in quantitative yield the tetrahy-
droxy derivatives 3a–e. A standard benzylation (NaH/
BnBr in DMF) afforded the tetra-O-benzyl hexosides 4a–
e (yield 80–90%).
The hydrolysis of the anomeric substituent of 4a–e was
carried out by treatment with aqueous trifluoroacetic acid
at 65 °C (yield 60–80%) (Scheme 2). These conditions
were previously employed for the hydrolysis of dichlo-
rovinyl ethers to dichloromethyl ketones by Suda and co-
workers.3a
It is known that the reaction of Ph3P/CCl4 complex on es-
ters and lactones leads to the formation of dichlorometh-
ylene ethers3 by a Wittig-like mechanism. On acetylated
sugar lactones, however, it is noteworthy that, in most cas-
es, only the carbonyl function of the lactone reacts in these
In conclusion, we have developed a new anomeric pro-
tecting group: a dichlorovinyl oside. It is easily and selec-
tively introduced starting from peracetylated sugars. This
Scheme 1
SYNTHESIS 2003, No. 18, pp 2831–2834
x
x.
x
x
.
2
0
0
3
Advanced online publication: 17.11.2003
DOI: 10.1055/s-2003-42487; Art ID: Z14503SS
© Georg Thieme Verlag Stuttgart · New York

2832
R. M. de Figueiredo et al.
PAPER
OAc
O
OH
O
MeONa, MeOH
quantitative
Cl
Cl
AcO
AcO
Cl
Cl
HO
HO
O
O
AcO
HO
H3C
H3C
2 a-e
3 a-e
OBn
O
OBn
O
NaH, BnBr
CF3
COOH aq.
65 °C
Cl
Cl
BnO
BnO
BnO
BnO
O
OH
DMF
80-90%
BnO
BnO
H3C
60-80%
4 a-e
5 a-e
Scheme 2
(2 ,2 -Dichloro-1 -methyl)ethenyl-2,3,4,6-tetra-O-acetyl- -D-
glycopyranosides or (2 ,2 -Dichloro-1 -methyl)ethenyl-2,3,4,6-
tetra-O-acetyl- -D-glycopyranosides (2a–e); General Procedure
The penta-O-acetyl glycopyranose 1 (1.17 g, 3 mmol), Ph3P (2.35
g, 9 mmol), KCl (2 g) were suspended in toluene (3 mL), CCl4 (3
mL) and pyridine (1.5 mL) (method a) or 1,2-dichloroethane (3 mL)
(method b) in a pyrex flask. The mixture was irradiated under mi-
crowave for 10 min (final temperature 90 °C), or heated with mag-
netic stirring at 90 °C for 50 min. The heterogeneous mixture was
filtered through a pad of silica gel, eluted with CH2Cl2–EtOAc (1:1)
and then separation on silica gel gave the dichlorovinyl glycoside 2.
protecting group, orthogonal with several groups (for ex-
ample such as ester, benzyl and silyl groups), is easily re-
moved under mild acidic conditions. As an illustration,
previously reported tedious access to tetrabenzylated hex-
opyranoses, especially in the case of galactose, was effi-
ciently achieved in 4 steps in good overall yields using
this new anomeric protecting group.
The microwave reactor was a Synthewave 402 monomode system
with focused waves. The temperature was controlled during the re-
action and was evaluated by an IR detector. Automatic control of
the irradiation (power and temperature) as well as data treatment
were followed by a computer system. Flash column chromatogra-
phy was performed using 35–70 m silica gel (60) purchased from
S.D.S. Company. 1H and 13C spectra were recorded at 250 MHz and
62.91 MHz and at 300 MHz and 75.49 MHz (Bruker WP 250, WP
300 respectively). 13C NMR chemical shifts for benzyl aromatic
carbons are not given. Mass spectra (CI) were recorded on AEI MS
9 spectrometer. Melting points were measured on a Reichert appa-
ratus and are uncorrected. Optical rotations were determined with a
Perkin-Elmer 241 polarimeter.
2a
Yield: 87%; white solid; mp 72–74 °C (heptane); [ ]D +129 (c 1.0,
CHCl3).
1H NMR (300 MHz, CDCl3): = 5.56 (t, J2,3 = J3,4 = 9.6 Hz, 1 H,
H-3), 5.55 (d, J1,2 = 4.4 Hz, 1 H, H-1), 5.09 (t, J4,5 = 9.6Hz, 1 H, H-
4), 4.93 (dd, 1 H, H-2), 4.25–4.05 (m, 3 H, H-5, H-6,6 ), 2.2–2.0 (m,
5 × CH3).
13C NMR (75.5 MHz, CDCl3): = 146.6 (C-1 ), 109.4 (C-2 ), 94.3
(C-1), 70.5 (C-2), 69,7 (C-3), 69.1 (C-5), 68.2 (C-4), 61.7 (C-6),
20.7 (CH3COO), 15.5 (C-3 ).
MS: m/z = 495 [M + K]+, 479 [M + Na]+, 331.
Table 1 Preparation of O-Dichlorovinyl Ether in Anomeric Position
Starting material
Product
MO
Activation
Classical
heating
87%a
64%b
73%a
54%a
OAc
O
OAc
O
AcO
AcO
AcO
R2
R2
AcO
AcO
R1
AcO
R1
2a R1 = OC(CCl2)CH3; R2 = H
Glucose 1a R1 = OAc; R2 = H
2b R1 = H; R2 = OC(CCl2)CH3
1b R1 = H; R2 = OAc
64%a
64%a
OAc
O
OAc
O
AcO
AcO
AcO
AcO
AcO
AcO
OAc
R2
OC(CCl2)CH3
Mannose 1c
2c
AcO
80%b
48%a
74%a
48%a
OAc
O
AcO
OAc
O
R2
AcO
AcO
AcO
AcO
R1
R1
2d R1 = OC(CCl2)CH3; R2 = H
Galactose 1d R1 = OAc; R2 = H
2e R1 = H; R2 = OC(CCl2)CH3
1e R1 = H; R2 = OAc
a Method a: PhCH3-pyridine, KCl, CCl4.
b Method b: PhCH3(CH2Cl)2, KCl, CCl4.
Synthesis 2003, No. 18, 2831–2834 © Thieme Stuttgart · New York

PAPER
O-Dichlorovinyl Osides
2833
Anal. Calcd for C17H22O10Cl2: C, 44.65; H, 4.84. Found: C, 44.35;
H, 4.86.
3a
White solid; mp 112–114 °C (EtOAc–heptane); [ ]D +68 (c 1.08,
CH3OH).
2b
13C NMR (75.5 MHz, CD3OD): = 148.9 (C-1 ), 107.2 (C-2 ), 98.3
(C-1), 75.5, 74.5 (C-2, C-3), 73.0 (C-5), 71.2 (C-4), 62.2 (C-6), 14.9
(C-3 ).
Yield: 64%; white solid; mp 118–120 °C (heptane); [ ]D –35 (c 0.6,
CHCl3).
1H NMR (300 MHz, CDCl3): = 5.30–5.05 (m, 3 H, H-2, H-3, H-
4), 4.85 (d, J1,2 = 9.2 Hz, 1 H, H-1), 4.24 (dd, J5,6 = 6.0 Hz, J6,6
15.5 Hz, 1 H, H-6), 4.15 (dd, J5,6 = 3.3 Hz, 1 H, H-6 ), 3.75 (m, 1
H, H-5), 1.95–2.21 (m, 5 × CH3).
13C NMR (75.5 MHz, CDCl3): = 147.9 (C-1 ), 110.9 (C-2 ), 99.4
(C-1), 72.5 (C-3), 72,2 (C-5), 71.0 (C-2), 68.3 (C-4), 61.9 (C-6),
20.6 (CH3COO), 17.1 (C-3 ).
Anal. Calcd for C9H14O6Cl2: C, 37.39; H, 4.88. Found: C, 37.41; H,
4.99.
=
3b
White solid; mp 114–116 °C (EtOAc–heptane); [ ]D +2 (c 1.15,
CH3OH).
13C NMR (75.5 MHz, CD3OD): = 149.4 (C-1 ), 107.0 (C-2 ),
101.1 (C-1), 78.3, 77.8 (C-3, C-5), 74.7 (C-2), 71.2 (C-4), 62.4 (C-
6), 15.4 (C-3 ).
Anal. Calcd for C17H22O10Cl2·1/2 H2O: C, 43.78; H, 4.97. Found: C,
43.91; H, 4.68.
Anal. Calcd for C9H14O6Cl2; C, 37.39; H, 4.88. Found: C, 37.69; H,
5.01.
2c
Yield: 64%; white solid; mp 96–98 °C (EtOAc–heptane); [ ]D +22
(c 1.5, CHCl3).
3c
1H NMR (300 MHz, CDCl3): = 5.45 (dd, J2,3 = 3.5 Hz, J3-4 = 10
White solid; mp 118-120 °C (i-PrOH–heptane).
Hz, 1 H, H-3), 5.40–5.25 (m, 3 H, H-1, H-2, H-4), 4.28 (dd, J5,6
5.5 Hz, J6,6 = 12 Hz, 1 H, H-6), 4.20–4.10 (m, 2 H, H-5, H-6), 2.2–
2.0 (m, 5 × CH3).
13C NMR (75.5 MHz, CDCl3): = 146.1 (C-1 ), 109.4 (C-2 ), 95.7
(C-1), 70.4 (C-5), 69.1 (C-3), 68.7 (C-2), 65.7 (C-4), 62.2 (C-6),
20.7 (CH3COO), 15.0 (C-3 ).
=
13C NMR (75.5 MHz, CD3OD): = 148.9 (C-1 ), 107.7 (C-2 );
100.0 (C-1), 76.3 (C-5), 72.0, 71.5 (C-2, C-3) 67.9 (C-4), 62.4 (C-
6), 15.1 (C-3 ).
Anal. Calcd for C9H14O6Cl2·1/2 H2O: C, 35.20; H, 5.25. Found: C,
35.52; H, 4.89.
Anal. Calcd for C17H22O10Cl2: C, 44.65; H, 4.84. Found: C, 44.54;
H, 4.86.
3d
White solid; mp 17 °C (decomp) (EtOAc).
13C NMR (75.5 MHz, CD3OD): = 149.0 (C-1 ), 107.1 (C-2 ), 98.6
(C-1), 74.0 (C-5), 70.7, 71.0, 69.5 (C-2, C-3, C-4), 62.2 (C-6), 14.9
(C-3 ).
2d
Yield: 80%; white solid; mp 106–108 °C (EtOAc–heptane); [ ]D
+132 (c 1.04, CHCl3).
Anal. Calcd for C9H14O6Cl2: C, 37.39; H, 4.88. Found: C, 37.25; H,
5.10.
1H NMR (250 MHz, CDCl3): = 5.61 (d, J1,2 = 3.9 Hz, 1 H, H-1),
5.52 (dd, J3,4 = 3.3 Hz, J4,5 = 1.3 Hz, 1 H, H-4), 5.43 (dd, J2,3 = 10.9
Hz, 1 H, H-3), 5.18 (dd, 1 H, H-2), 4.42 (dt, J5,6 = J5-6 = 6.2 Hz, 1
H, H-5), 4.15 (dd, J6,6 = 10.9 Hz, 1 H, H-6), 4.05 (dd, 1 H, H-6 ),
2.25–1.95 (m, 5 × CH3).
13C NMR (62.9 MHz, CDCl3): = 146.7 (C-1 ), 109.4 (C-2 ), 94.8
(C-1), 68.1 (C-5), 67.8 (C-4), 67.6 (C-2), 67.2 (C-3), 61.7 (C-6),
20.6 (CH3COO), 15.5 (C-3 ).
3e
White solid; mp 152–153 °C (EtOAc); [ ]D +54 (c 1, CH3OH).
13C NMR (75.5 MHz, CD3OD): = 149.6 (C-1 ), 107.3 (C-2 ),
101.9 (C-1), 77.2 (C-5), 74.8 (C-3), 72.2 (C-2), 70.2 (C-4), 62.4 (C-
6), 15.5 (C-3 ).
Anal. Calcd for C9H14O6Cl2·1/4 H2O: C, 37.06; H, 5.01. Found: C,
36.93; H, 4.91.
Anal. Calcd for C17H22O10Cl2: C, 44.65; H, 4.84. Found: C, 44.38;
H, 4.82.
(2 ,2 -Dichloro-1 -methyl)ethenyl-2,3,4,6-tetra-O-benzyl- -D-
glycopyranosides or (2 ,2 -Dichloro-1 -methyl)ethenyl-2,3,4,6-
tetra-O-benzyl- -D-glycopyranosides (4a–e); General Proce-
dure
The tetrol derivative 3 (434 mg, 1.5 mmol) was dissolved in DMF
(5 mL), under Ar. NaH (240 mg, 10 mmol) then was added under
stirring followed bybenzyl bromide (1 mL, 8 mmol). After 4 h at r.t.,
the reaction was quenched by MeOH (1 mL). The mixture was di-
luted with CH2Cl2 and water; the organic phase was separated, dried
on MgSO4 and concentrated to dryness. The pure derivative 4 was
isolated by chromatography on silica gel.
2e
Yield: 48%; colorless oil; [ ]D –21 (c 1.3, CHCl3).
1H NMR (250 MHz, CDCl3): = 5.42 (dd, J3,4 = 3.7 Hz, J4,5 = 2.9
Hz, 1 H, H-4), 5.36 (dd, J1,2 = 7.9 Hz, J2,3 = 10.4 Hz, 1 H, H-2), 5.05
(dd, 1 H, H-3), 4.81 (d, 1 H, H-1), 4.19 (dd, J5,6 = J5,6 = 6.7 Hz, J6,6
= 11.0 Hz, 1 H, H-6), 4.12 (dd, 1 H, H-6 ), 3.95 (t, 1 H, H-5), 1.95–
2.22 (m, 5 × CH3).
13C NMR (62.9 MHz, CDCl3): = 148.1 (C-1 ), 110.4 (C-2 ),
100.1(C-1), 71.3 (C-5), 70.7 (C-3), 68.4 (C-2), 66.9 (C-4), 61.4 (C-
6), 20.7 (CH3COO), 17.3 (C-3 ).
Anal. Calcd for C17H22O10Cl2: C, 44.65; H, 4.84. Found: C, 44.28;
H, 4.93.
4a
Yield: 90%; colorless oil; [ ]D +24 (c 1.2, CHCl3).
1H NMR (300 MHz, CDCl3): = 7.45–7.10 (m, 20 H, aromatic),
5.20 (d, J1,2 = 2.8 Hz, 1 H, H-1), 5.00–4.38 (m, 8 H, 4 × CH2Ph),
(2 ,2 -Dichloro-1 -methyl)ethenyl- -D-glycopyranosides or
(2 ,2 -Dichloro-1 -methyl)ethenyl- -D-glycopyranosides (3a–e);
General Procedure
To tetra-O-acetyl glycoside 2 (500 mg, 1.1 mmol) in absolute
MeOH (5 mL) was added MeONa (25 mg). After 1 h, the solution
was neutralized with Amberlite IRC 50 H. After filtration and evap-
oration, the residue 3 was crystallized.
4.08 (t, J2,3 = J3,4 = 9.5 Hz, 1 H, H-3), 3.95 (dt, J4,5 = 9.6 Hz, J5,6
=
J5,6 = 2.9 Hz, 1 H, H-5), 3.62 (dd, 1 H, H-2), 3.77–3.55 (m, 3 H, H-
4, H-6, H-6 ), 1.98 (s, 3 H, CH3).
Synthesis 2003, No. 18, 2831–2834 © Thieme Stuttgart · New York

2834
R. M. de Figueiredo et al.
PAPER
13C NMR (75.5 MHz, CDCl3): = 146.7 (C-1 ), 107.4 (C-2 ), 95.3
(C-1), 81.5 (C-2), 79.4 (C-3), 76.5 (C-4), 75.7, 74.9, 73.8 and 73.3
(CH2Ph), 71.8 (C-5), 68.0 (C-6), 14.8 (C-3 ).
13C NMR (75.5 MHz, CDCl3): = 148.1 (C-1 ), 106.9 (C-2 ), 101.2
(C-1), 82.1 (C-3), 79.1 (C-2), 74.7 (CH2Ph), 74.0 (C-5), 73.7
(CH2Ph), 73.4 (C-4), 73.2 (CH2Ph), 68.9 (C-6), 16.1 (C-3 ).
Anal. Calcd for C37H38O6Cl2·1/2 H2O: C, 67.47; H, 5.97. Found: C,
67.57; H, 5.91.
Anal. Calcd for C37H38O6Cl2: C, 68.41; H, 5.90. Found: C, 68.66; H,
5.95.
4b
2,3,4,6-Tetra-O-benzyl- -D-glycopyranoses or 2,3,4,6-Tetra-O-
benzyl- -D-glycopyranoses (5a–e); General Procedure
Yield: 80%; white solid; mp 78–79 °C (pentane); [ ]D +2 (c 1.68,
CHCl3).
The tetra-O-benzyl glycoside 4 (974 mg, 1.5 mmol) was dissolved
in a solution of trifluoroacetic acid (4.5 mL) and water (1.5 mL) and
heated at 65 °C for 3 h. The mixture was evaporated to dryness. The
residue was crystallized [for glucose 5a (65% yield) and galactose
5e (70% yield)] or separated on silica gel [for mannose 5c (80%
yield)]. Their physical data were in agreement with the literature.5
1H NMR (300 MHz, CDCl3): = 7.45–7.10 (m, 20 H, aromatic),
5.20 (d, J1,2 = 6.6 Hz, 1 H, H-1), 5.15–4.60 (m, 8 H, 4 × CH2Ph),
3.83–3.65 (m, 5 H, H-2, H-3, H-4, H-6, H-6 ), 3.50 (m, 1 H, H-5),
2.12 (s, 3 H, CH3).
13C NMR (75.5 MHz, CDCl3): = 147.9 (C-1 ), 107.5 (C-2 ), 100.8
(C-1), 84.6 (C-3), 81.9 (C-2), 76.7 (C-4), 75.8 (CH2Ph), 75.4 (C-5),
75.2, 73.6 (CH2Ph), 68.8 (C-6), 16.0 (C-3 ).
Acknowledgment
Anal. Calcd for C37H38O6Cl2: C, 68.41; H, 5.90. Found: C, 68.34; H,
5.92.
We are grateful to Professor P. Potier for a grant (R.M.F.).
4c
References
Yield: 85%; colorless oil; [ ]D +15 (c 1.3, CHCl3).
(1) (a) Nicolaou, K. C.; Mitchell, H. J. Angew. Chem. Int. Ed.
2001, 40, 1576. (b) Sznaidman, M. In Bioorganic
Chemistry: Carbohydrates; Hecht, S. M., Ed.; Oxford
University Press: New York, 1999, 1–56. (c) Witczak, Z. J.
In Carbohydrate in Drug Design; Witczak, K. A.; Nieforth,
Z. J., Eds.; Marcel Dekker: New York, 1997, 1–37.
(2) (a) Schmidt, R. R.; Jung, K.-H. In Preparative Carbohydrate
Chemistry; Hanessian, S., Ed.; Marcel Dekker: New York,
1997, 283–312. (b) Fraser-Reid, B.; Madsen, R. In
Preparative Carbohydrate Chemistry; Hanessian, S., Ed.;
Marcel Dekker: New York, 1997, 339–356. (c) Lou, B.;
Huynh, H. K.; Hanessian, S. In Preparative Carbohydrate
Chemistry; Hanessian, S., Ed.; Marcel Dekker: New York,
1997, 431–448. (d) Lou, B.; Eckhardt, E.; Hanessian, S. In
Preparative Carbohydrate Chemistry; Hanessian, S., Ed.;
Marcel Dekker: New York, 1997, 449. (e) Danishefsky, S.
J.; Allen, J. R. Angew. Chem. Int. Ed. 2000, 39, 836.
(3) (a) Suda, M.; Fukushima, A. Tetrahedron Lett. 1981, 22,
759. (b) Corey, E. J.; Fuchs, P. L. Tetrahedron Lett. 1972,
3769.
1H NMR (250 MHz, CDCl3): = 7.45–7.10 (m, 20 H, aromatic),
5.29 (d, J1,2 = 1.8 Hz, 1 H, H-1), 4.95–4.40 (m, 8 H, 4 × CH2Ph),
4.10–3.95 (m, 2 H, H-3, H-4), 3.93–3.84 (m, 2 H, H-2, H-5), 3.80
(dd, J5,6 = 4.9 Hz, J6,6 = 10.5 Hz, 1 H, H-6), 3.70 (dd, J5,6 = 2 Hz, 1
H, H-6 ), 2.04 (s, 3 H, CH3).
13C NMR (75.5 MHz, CDCl3): = 147.5 (C-1 ), 108.2 (C-2), 97.4
(C-1), 79.6 (C-3), 75.0 (CH2Ph), 74.5 (C-4), 73.4 (C-2, C-5), 73.3
(CH2Ph), 73.1 (CH2Ph), 72.6 (CH2Ph), 69.0 (C-6), 15.6 (C-3 ).
Anal. Calcd for C37H38O6Cl2: C, 68.41; H, 5.90. Found: C, 68.36; H,
5.94.
4d
Yield: 80%; colorless oil; [ ]D +26 (c 1.4, CHCl3).
1H NMR (300 MHz, CDCl3): = 7.45–7.10 (m, 20 H, aromatic),
5.25 (d, J1,2 = 2.2 Hz, 1 H, H-1), 5.00–4.40 (m, 8 H, 4 × CH2Ph),
4.20–4.10 (m, 3 H, H-2, H-3, H-5), 4.03 (m, 1 H, H-4), 3.5 (m, 2 H,
H-6, H-6 ), 2.0 (s, 3 H, CH3).
13C NMR (75.5 MHz, CDCl3): = 147.1 (C-1 ), 107.4 (C-2 ), 96.1
(C-1), 78.7 (C-3), 75.9 (C-2), 75.1 (C-4), 74.0, 73.6, 73.2 (CH2Ph),
71.2 (C-5), 68.6 (C-6), 14.9 (C-3 ).
(4) (a) Chapleur, Y. J. Chem. Soc., Chem. Commun. 1984, 449.
(b) Lakhrissi, M.; Chapleur, Y. Synlett 1991, 583.
(c) Lakhrissi, M.; Chapleur, Y. J. Org. Chem. 1994, 59,
5752. (d) Bandzouzi, A.; Lakhrissi, M.; Chapleur, Y. J.
Chem. Soc., Perkin Trans. 1 1992, 1471.
Anal. Calcd for C37H38O6Cl2; C, 68.41; H, 5.90. Found: C, 68.44; H,
6.06.
(5) (a) Perrine, T. D.; Glaudemans, C. P. J.; Ness, R. K.; Kyle,
J.; Fletcher, H. G. Jr. J. Org. Chem. 1967, 32, 664.
(b) Koto, S.; Morishima, N.; Miyata, Y.; Zen, S. Bull. Chem.
Soc. Jpn. 1976, 49, 2639. (c) Lemieux, R. U.; Suemiti, R.;
Gunner, S. W. Can. J. Chem. 1968, 1040.
4e
Yield: 80%; colorless oil; [ ]D +20 (c 0.7, CHCl3).
1H NMR (250 MHz, CDCl3): = 7.45–7.10 (m, 20 H, aromatic),
5.00–4.35 (m, 8 H, 4 × CH2Ph), 4.73 (d, J1,2 = 7.5 Hz, 1 H, H-1),
3.98 (dd, J1,2 = 7.5 Hz, J2,3 = 9.7 Hz, 1 H, H-2), 3.88 (m, 1 H, H-4),
3.60–3.50 (m, 4 H, H-3, H-5, H-6, H-6 ), 2.1 (s, 3 H, CH3).
Synthesis 2003, No. 18, 2831–2834 © Thieme Stuttgart · New York