A straightforward synthesis of 1,2-dihydronaphtho[2,1-b]furans from 2- naphthols

Article abstract of DOI:10.1055/s-1999-3536

A one-step synthesis of ethyl 1,2-dihydronaphtho[2,1-b]furan-2- carboxylates 2a-g from substituted 2-naphthols and ethyl 2,3- dibromopropanoate is described. 3,4-Dibromobutan-2-one and 2- chloroacrylonitrile react with 2-naphthol (1a) to afford the corres

Full text of DOI:10.1055/s-1999-3536

PAPER
1241
A Straightforward Synthesis of 1,2-Dihydronaphtho[2,1-b]furans from 2-
Naphthols
Axelle Arrault, Frédérique Touzeau, Gérald Guillaumet, Jean-Yves Mérour*
Institut de Chimie Organique et Analytique, associé au CNRS, Université d’Orléans, BP6759, F-45067 Orléans Cedex 2, France
Fax: +33(2)38417081; E-mail: jean-yves.merour@univ-orleans.fr
Received 14 December 1998; revised 13 March 1999
compounds 2b–e, respectively, in relatively good yields
(65–80%) except for 2c (35%) (Scheme 1). Under the
same conditions, the 6-bromo-2-naphthol (1g) gave the
bromonaphtho[2,1-b]furan 2g (yield 67%). The 1,2-dihy-
Abstract: A one-step synthesis of ethyl 1,2-dihydronaphtho[2,1-
b]furan-2-carboxylates 2a–g from substituted 2-naphthols and ethyl
2,3-dibromopropanoate is described. 3,4-Dibromobutan-2-one and
2-chloroacrylonitrile react with 2-naphthol (1a) to afford the corre-
sponding 2-cyano- or 2-acetylnaphtho[2,1-b]furans 6 and 7, respec- dro compounds 2a, 2d were easily and efficiently aroma-
tized to the corresponding naphtho[2,1-b]furans 3a9and
tively.
3d, respectively, by oxidation with 2,3-dichloro-5,6-di-
cyano-1,4-benzoquinone (DDQ) in refluxing toluene
(Scheme 1, Tables 1 and 2).
Key words: 2-naphthols, ethyl 1,2-dihydronaphtho[2,1-b]furan-2-
carboxylates, aromatization, 1,2-dihydronaphtho[2,1-b]furan-2-
carbonitrile, 1-(1,2-dihydronaphtho[2,1-b] furan-2-yl)ethan-1-one
2,3-Dihydro-1,4-benzodioxin and 2,3-dihydro-1,4-benz-
oxazine derivatives have received increasing attention
due to their pharmacological properties and therefore a
large number of related compounds have been synthe-
sized in the past two decades.1 In the course of our search
for new antihypertensive drugs, we have now investigated
the replacement of the benzo group of 2,3-dihydro-1,4-
benzoxazine by a naphtho moiety. 2,3-Dihydro-1,4-
benzodioxin2,3 or 2,3-dihydro-1,4-benzoxazine4,5 deriva-
tives are usually obtained by the reaction of ethyl 2,3-di-
bromopropanoate with 1,2-dihydroxybenzene or 2-
aminophenol, respectively. Unfortunately, in our hands,
the reaction of 3-amino-2-naphthol (1b) with ethyl 2,3-di-
bromopropanoate according to a standard method6 did not
afford the desired ethyl 3,4-dihydro-2H-naphtho[2,3-
b]oxazine-2-carboxylate (I), instead only the naph-
tho[2,1-b]furan 2b was obtained. Usually the synthesis of
such framework, which has been sparingly de-
scribed,7needs the use of functionalized naphthols8 such
as 1-substituted-2-naphthols, which are not always easily
available.
Scheme 1
The formation of naphtho[2,1-b]furan is unexpected and
may be attributed to the different reactivity of naphthol
compared to phenol.10 In order to support the structure of
the naphtho[2,1-b]furan derivative 2b, the free amino
group (if present) has been converted into the acetylated
derivative 2c (82%) and the benzoylated analog 2d (73%),
respectively, and the structure of products obtained were
established. The 1H NMR spectrum of 2a was identical to
the known compound8,11 and show inter alia a missing
peri-H. More, 2D NMR Noesy experiments confirmed the
naphtho[2,1-b]furan ring.
Treatment of 2-naphthol (1a) with ethyl 2,3-dibromo-
propanoate in refluxing acetone in the presence of potas-
sium carbonate gave the ethyl naphtho[2,1-b]furan-2-
carboxylate (2a)7,8 in good yield (83%). Reaction of other
3-substituted-2-naphthols such as 3-amino 1b, 3-protect-
ed amino 1c or 1d, or 3-benzyloxy 1e, afforded the desired
Since ethyl 2,3-dibromopropanoate is easily transformed
in situ into ethyl 2-bromoacrylate with potassium carbon-
ate in refluxing acetone, compound 1a was treated with
this acrylate to give the desired product 2a in 50% yield.
Optimization of the reaction conditions , e.g. acetonitrile/
Synthesis 1999, No. 7, 1241–1245 ISSN 0039-7881 © Thieme Stuttgart · New York

1242
A. Arrault et al.
PAPER
reflux, instead of acetone/reflux, allowed us to obtain 2a
in 71% yield. The suggested mechanism for the formation
of the dihydronaphtho[2,1-b]furan ring is given in
Scheme 2:
Scheme 3
Since we have interest in compounds of type 2 having an
hydroxy substituent in position-3, compound 2e was hy-
drogenolysed to form directly the naphthol 2f (93%).
Naphthol 2f was reacted with ethyl 2,3-dibromopro-
panoate to afford 5 (44%) as a mixture of diastereomers in
the ratio of 65:35 (HPLC and NMR analysis) (Scheme 4).
Scheme 2
First, a Michael-type addition of the naphthalenolate A to
the 2-bromoacrylate generates the C–C bond forming B.
Aromatization and formation of the 2-naphthalenolate an-
ion gives the intermediate C. This is followed by an in-
tramolecular nucleophilic substitution on the carbon
bearing the bromo atom in C affording the dihydrofuran
ring 2a. We cannot completely exclude a direct displace-
ment of the 3-bromo atom of 2,3-dibromopropanoate by
the 2-naphthalenolate A generating the same intermediate
B in the first step. This behavior is not reported in the re-
action of ethyl 2-bromoacrylate with phenol itself since a
mixture of O-alkylated derivatives is obtained.12 No reac-
tion occurred when 2-naphthol (1a) was treated with ethyl
acrylate instead of ethyl 2-bromoacrylate, indicating the
need of a leaving group such as the bromide ion in order
to generate the dihydrofuran ring.
Scheme 4
In order to broaden the scope of this reaction, we have in-
vestigated the synthesis of compounds 6 and 78 which
possess a nitrile or a keto group, respectively, instead of
an ester group on the naphtho[2,1-b]furan skeleton. Fol-
lowing the same methodology as described above, the re-
action of naphthol 1a with 2-chloroacrylonitrile and 3,4-
dibromobutan-2-one afforded 6 and 7, respectively. The
1,2-dihydronaphtho[2,1-b]furan derivatives 6 and 7 were
easily and efficiently aromatized to the corresponding
naphtho[2,1-b]furan 815 (85%) and 916 (90%), respective-
ly, by oxidation with DDQ in refluxing toluene (Scheme
5, Tables 1 and 2).
The reaction of ethyl acrylate, which did not possess a
leaving group, with 2-naphthol (1a) gave a retro-Michael
as the predominant reaction; in the case of ethyl 2-bro-
moacrylate or ethyl 2,3-dibromopropanoate, the presence
of a bromine atom as a leaving group allows the reaction
to go to completion with the formation of the dihydrofu-
ran ring which displaces all the equilibria. To illustrate
this behavior, Stanovnik et al13 have reported a C-alkyla-
tion of 2-naphthol (1a) with methyl (Z)-2-acetylamino-3-
dimethylaminopropenoate according to a Michael-type
addition to afford the lactone derivative 2-acetylamino-
3H-benzo[f]chromen-3-one by expulsion of the dimethy-
lamino group.
In conclusion, we have described an efficient one-pot syn-
thesis of several functionalized 1,2-dihydronaphtho[2,1-
b] derivatives from easily available 2-naphthols. The be-
havior of 1-naphthols is under investigation and results
will be reported in due course.
1H NMR and 13C NMR spectra were obtained with a Bruker instru-
ment Avance DPX250 (250 MHz) in CDCl3 with TMS as internal
standard, chemical shifts (δ values) were reported in parts per mil-
lion and coupling constants (J values) in Hz. IR spectra were record-
ed as a thin film on NaCl plates for the oils and in a KBr pellet for
the solids on a Perkin-Elmer spectrometer FT PARAGON 1000 PC.
MS were recorded on a Perkin-Elmer mass spectrometer SCIEX
When 2,3-dihydroxynaphthalene (1f) was treated by ethyl
2,3-dibromopropanoate, the dioxino derivative 414 was
exclusively obtained without formation of a naphtho[2,1-
b]furan derivative (Scheme 3). The formation of 4 was the
result of a preferential O-alkylation.
Synthesis 1999, No. 7, 1241–1245 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
A Straightforward Synthesis of 1,2-Dihydronaphtho[2,1-b]furans from 2-Naphthols
1243
chromatography on silica gel (EtOAc/petroleum ether, 2:1) to give
2a (281 mg, 83%) as a yellow oil (Tables 1 and 2).
Method B: To a solution of 2-naphthol ( 1a; 200 mg, 1.38 mmol) in
anhyd MeCN (4 mL) were added K2CO3 (536 mg, 3.88 mmol) and
ethyl 2-bromoacrylate (274 mg, 1.53 mmol). The mixture was re-
fluxed for 18 h and cooled to r.t. and worked up similarly as for
Method A to give 2a (240 mg, 71%) as a yellow oil (Tables 1 and 2)
Ethyl 4-Hydroxy-1,2-dihydronaphtho[2,1-b]furan-2-carboxy-
late (2f)
A solution of 2e (1.15 g, 3.30 mmol) in MeOH (40 mL) and Pd/C
(10%) (115 mg) was stirred in a Parr apparatus under H2 (1 atm) for
18 h at r.t. The mixture was filtered on Celite and then evaporated.
Purification by column chromatography on silica gel (EtOAc/petro-
leum ether, 2:1) gave 2f (800 mg, 93%) as a white solid (Tables 1
and 2).
Scheme 5
Ethyl Naphtho[2,1-b]furan-2-carboxylate (3a); Typical proce-
dure
API 300 (ionspray or heat nebuliser). Mps were measured using a
Kofler hot stage apparatus and are uncorrected. Flash chromatogra-
phy (FC) was performed on silica gel (Merck 60, 230–400 mesh).
TLC was performed on pre-coated silica gel plates (Merck 60,
F254, 0,25mm). The solvents used were HPLC grade. Petroleum
ether used had bp ??°C.
DDQ (238 mg, 1.05 mmol) was added to a solution of 2a (243 mg,
1 mmol) in toluene (6 mL). The mixture was refluxed for 5 h and
then cooled to r.t. The solution was hydrolyzed and neutralized with
aq 5% NaOH solution. The organics were extracted with EtOAc (3
× 75 mL) and the combined extracts were dried (MgSO4). After
evaporation of the solvent, the residual syrup was purified by col-
umn chromatography on silica gel (EtOAc/petroleum ether, 2:1) to
give 3a (200 mg, 83%) as a yellow solid (Tables 1 and 2).
The naphthols 1c17, 1d18, 1e19 were prepared according to literature
procedure
.
1,2-Dihydronaphtho[2,1-b]furan-2-carbonitrile (6)
Prepared according to Method B, as described for 2a, using 2-chlo-
roacrylonitrile instead of ethyl 2-bromoacrylate.The residual red-
dish syrup was purified by column chromatography on silica gel
(EtOAc/petroleum ether, 1:4) to give 6 (1.02 g, 75%) as a white sol-
id (Tables 1 and 2).
Ethyl 1,2-Dihydronaphtho[2,1-b]furan-2-carboxylate (2a);
Typical Procedure
Method A: To a solution of 2-naphthol ( 1a; 200 mg, 1.38 mmol) in
anhyd acetone (4 mL) were added K2CO3 (536 mg, 3.88 mmol) and
ethyl 2,3-dibromopropanoate (0.22 mL, 1.53 mmol). The mixture
was refluxed for 18 h and cooled to r.t. The salts were filtered and
washed with acetone. The filtrate was evaporated in vacuo and the
residue poured into H2O (15 mL), extracted with EtOAc (3 × 20
mL) and the combined extracts were dried (MgSO4). After evapo-
ration of the solvent, the residual reddish syrup was purified by flash
1-(1,2-Dihydronaphtho[2,1-b]furan-2-yl)ethan-1-one (7)
Prepared according to Method A, as described for 2a, using 3,4-di-
bromobutan-2-one instead of ethyl 2,3-dibromopropanoate. The re-
sidual reddish syrup was purified by column chromatography on
silica gel (EtOAc/petroleum ether, 1:3) to give 7 (880 mg, 60%)
(Tables 1 and 2).
Table 1 Characterisation of Compounds 2–9
Producta
Yield
(%)
Method
mp (°C)b
IR (film/KBr)
MS
ν (cm–1)
m/z (M++1)
2a7,8,11
83
71
80
35
65
75
93
67
83
73
77
44
75
60
85
90
A
B
A
A
A
A
A
A
_
oil
1727 (C=O)
243
2b
2c
2d
2e
2f
2g
3a9,15
3d
414
5
131–132
137–138
oil
104–105
154–155
oil
98–99
oil
oil
oil
131–132
oil
81–82
113–114
1736 (C=O), 3342 (NH), 3442 (NH)
1680 (C=O), 1750 (C=O), 3317 (NH)
1674 (C=O), 1754 (C=O), 3420 (NH)
1746 (C=O)
1724 (C=O), 3257 (OH)
1756 (C=O)
1727 (C=O)
1660 (C=O), 1732 (C=O), 3332 (NH)
1757 (C=O)
1759 (C=O)
2244 (C≡N)
1723 (C=O)
2229 (C≡N)
258
300
362
349
259
321, 323
241
360
259
357
196
213
194
211
_
A
A
B
A
–
6
78
815
916
_
1703 (C=O)
a Satisfactory elemental analyses obtained: C ± 0.35, H ± 0.16, N ± 0.19.
b Literature values: 2a,8 bp 140°C/0.1 Torr; 3a,15 mp 97–98°C; 4,14 mp 61–62°C; 7,8 bp 130°C/0.1 Torr; 8,15 mp 86°C; 9,16 mp 114°C.
Synthesis 1999, No. 7, 1241–1245 ISSN 0039-7881 © Thieme Stuttgart · New York

1244
A. Arrault et al.
PAPER
Table 2 1H NMR and 13C NMR data of Compounds 2–9
Product
1H NMR (CDCl3/TMS)
13C NMR (CDCl3/TMS)
d, J (Hz)
d
2a
1.33 (t, 3H, J = 7.1, CH3), 3.64 (dd, 1H, J = 7.0, 16.0, ArCH2),
3.80 (dd, 1H, J = 11.2, 16.0, ArCH2), 4.30 (q, 2H, J = 7.1,
OCH2), 5.37 (dd, 1H, J = 7.0, 11.2, HCO), 7.22 (d, 1H, J = 8.0,
Harom), 7.33 (t, 1H, J = 8.0, Harom), 7.48 (t, 1H, J = 8.0, Harom),
7.57 (d, 1H, J = 8.0, Harom), 7.71 (d, 1H, J = 8.0, Harom),
16.6 (CH3), 35.4 (CH2), 64.1 (CH2), 82.2 (CH), 114.5 (CH),
119.2 (C), 125.1 (CH), 125.7 (CH), 128.9 (C), 129.3 (CH),
131.2 (CH), 132.0 (CH), 132.8 (C), 159.2 (C), 173.7 (C=O)
7.81 (d, 1H, J = 8.0, Harom
)
2b
1.33 (t, 3H, J = 7.1, CH3), 3.64 (dd, 1H, J = 7.0, 15.2, ArCH2),
3.82 (dd, 1H, J = 11.1, 15.2, ArCH2), 3.98 (br s, 2H, NH2),
4.29 (q, 2H, J = 7.1, OCH2), 5.39 (dd, 1H, J = 7.0, 11.1, HCO),
6.91 (s, 1H, Harom), 7.25 (m, 2H, Harom), 7.45 (m, 1H, Harom),
14.2 (CH3), 33.6 (CH2), 61.7 (CH2), 80.0 (CH), 109.4 (CH),
116.8 (C), 122.5 (CH), 123.1 (CH), 123.7 (CH), 124.6 (C),
126.4 (CH), 131.2 (C), 132.2 (C), 147.7 (C), 171.2 (C=O)
7.59 (m, 1H, Harom
)
2c
1.30 (t, 3H, J = 7.1, CH3), 2.24 (s, 3H, COCH3), 3.63 (dd, 1H,
J = 7.1, 15.6, ArCH2), 3.82 (dd, 1H, J = 10.8, 15.6, ArCH2),
4,29 (q, 2H, J = 7.1, OCH2), 5.38 (dd, 1H, J = 7.1, 10.8, HCO),
7.39 (m, 3H, Harom), 7.79 (m, 2H, Harom), 8.68 (br s, 1H, NH)
13.3 (CH3), 24.0 (CH3), 32.8 (CH2), 61.0 (CH2), 79.4 (CH),
115.7 (C), 116.1 (CH), 121.4 (CH), 122.6 (C), 123.2 (CH),
124.8 (CH), 125.9 (C), 127.9 (CH), 129.6 (C), 146.3 (C),
167.7 (C=O), 169.9 (C=O)
2d
1.32 (m, 3H, CH3), 3.55 (m, 1H, ArCH2), 3.80 (m, 1H, ArCH2),
4.27 (q, 2H, J = 7.2, OCH2), 5.40 (m, 1H, HCO), 7.33–7.52
(m, 7H, Harom), 7.92 (m, 3H, Harom), 8.84 (br s, 1H, NH)
14.6 (CH3), 34.2 (CH2), 62.3 (CH2), 80.7 (CH), 117.1 (C),
117.5 (CH), 122.7 (CH), 123.9 (C), 124.5 (CH), 126.2 (C),
136.3 (CH), 127.0 (C), 127.3 (C), 127.6 (2CH), 129.2
(2CH), 129.3 (CH), 130.9 (C), 132.4 (CH), 165.3 (C=O),
171.1 (C=O)
2e
2f
1.32 (t, 3H, J = 7,1, CH3), 3.67 (dd, 1H, J = 6.9, 15.5, ArCH2),
3.86 (dd, 1H, J = 10.7, 15.5, ArCH2), 4.20 (q, 2H, J = 7.1,
OCH2), 5.17 (s, 2H, OCH2Ph), 5.34 (dd, 1H, J = 6.9, 10.7,
HCO), 7.12 (s, 1H, Harom), 7.33 (m, 5H, Harom), 7.51 (m, 3H,
14.6 (CH3), 33.9 (CH2), 62.1 (CH2), 71.1 (CH2), 80.7 (CH),
109.7 (CH), 119.1 (C), 122.9 (CH), 124.4 (CH), 125.1
(CH), 126.9 (C), 127.9 (2CH), 128.0 (CH), 128.4 (CH),
129.0 (2CH), 131.1 (C), 133.1 (C), 145.2 (C), 148.7 (C),
171.5 (C=O)
Harom), 7.67 (d, 1H, J = 7.6, Harom
)
1.35 (t, 3H, J = 7.1, CH3), 3.00 (br s, 1H, OH), 3.72 (dd, 1H,
J = 6.9, 15.5, ArCH2), 3.91 (dd, 1H, J = 10.8, 15.5, ArCH2),
4.53 (q, 2H, J = 7.1, OCH2), 5.47 (dd, 1H, J=6.9, 10.8, HCO),
7.22 (s, 1H, Harom), 7.36 (m, 2H, Harom), 7.52 (m, 1H, Harom),
14.6 (CH3), 34.1 (CH2), 62.4 (CH2), 80.7 (CH), 111.8 (CH),
118.4 (C), 122.9 (CH), 124.4 (CH), 124.7 (CH), 125.8 (C),
127.8 (CH), 131.4 (C), 141.7 (C), 148.5 (C), 171.4 (C=O)
7.71 (m, 1H, Harom
)
2g
3a
3d
1.30 (t, 3H, J = 7.1, CH3), 3.55-3.64 (m, 1H, ArCH2), 3.71–3.81
(m, 1H, ArCH2), 4.28 (q, 2H, J = 7.1, OCH2), 5.36 (dd, 1H,
J = 7.5, 10.5, HCO), 7.18 (d, 1H, J = 7.8, Harom), 7.28 (d, 1H,
J = 7.8, Harom), 7.47-58 (m, 2H, Harom), 7.90 (d, 1H, J = 2.8,
13.5 (CH3), 32.1 (CH2), 61.1 (CH2), 79.1 (CH), 112.4 (CH),
116.1 (C), 116.4 (C), 123. 7 (CH), 127.9 (CH), 128.1 (C),
129.4 (CH), 130.0 (CH), 138,5 (C), 156.4 (C), 170.3 (C=O)
Harom
)
1.46 (t, 3H, J = 7.1, CH3), 4.48 (q, 2H, J = 7.1, OCH2), 7.48
(td, 1H, J = 1.3, 8.2, Harom), 7.62 (td, 1H, J = 1.3, 8.2, Harom),
7.67 (td, 1H, J = 1.3, 8.2, Harom), 7.84 (d, 1H, J = 8.2, Harom),
7.95 (d, 1H, J = 8.2, Harom), 7.99 (d, 1H, J = 0.9, =CH), 8.13
14.4 (CH3), 61.4 (CH2), 112.7 (2CH), 122.5 (C), 123.3
(CH), 125.9 (CH), 127.2 (CH), 128.0 (C), 128.9 (CH),
129.0 (CH), 130.4 (C), 145.0 (C), 153.95 (C), 159.5 (C=O)
(d, 1H, J = 8.2, Harom
)
1.44 (t, 3H, J = 7.2, CH3), 4.44 (q, 2H, J =7 .2, OCH2),
7.46–7.61 (m, 5H, Harom), 7.88-7.93 (m, 1H, Harom), 7.95
(s, 1H, =CH), 7.95-8.01 (m, 3H, Harom), 8.59 (s, 1H, Harom),
8.90 (br s, 1H, NH)
14.8 (CH3), 62.0 (CH2), 113.8 (CH), 117.4 (CH), 123.2
(CH), 123.3(C), 123.9 (C), 125.1 (C), 126.3 (CH), 126.5
(CH), 127.7 (2CH), 129.3 (2CH), 129.5 (CH), 131.8 (C),
132.6 (CH), 134.7 (C), 145.3 (C), 146.0 (C), 159.5 (C=O),
166.3 (C=O)
4
5
1.25 (t, 3H, J = 7.2, CH3), 4.15 (q, 2H, J = 7.1, OCH2), 4,43
(dd, 1H, J=3.0, 11.5, OCH2), 4,30–4.47 (m, 2H, OCH2), 4.85
(dd, 1H, J = 3.0, 4.4, HCO), 7.28 (m, 3H, Harom), 7.41 (s, 1H,
16.9 (CH3), 65.5 (CH2), 67.9 (CH2), 74.9 (CH), 115.6 (CH),
116.0 (CH), 127.1 (2CH), 127.9 (2CH), 129.1 (C), 129.4
(C), 145.5 (C), 146.2 (C), 170.9 (C=O)
Harom), 7.59–7.63 (m, 2H, Harom
)
1.34 (m, 6H, J = 7.0, 2 CH3), 3.72 (m, 4H, 2 ArCH2), 4.29
(m, 4H, 2 OCH2), 5.38 (t, 1H, J = 7.0, HCO, dia A), 5.43 (t, 1H,
J = 7.0, HCO, dia B) , 7.38 (m, 2H, Harom), 7.53 (m, 2H, Harom
15.8 (2CH3), 34.9 (2CH2), 63.4 (2CH2), 82.0 (2CH), 121.1
(2C), 124.2 (2CH), 125.8 (2CH), 127.7 (2C), 144.8 (2C),
172.6 (2C=O)
)
Synthesis 1999, No. 7, 1241–1245 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
A Straightforward Synthesis of 1,2-Dihydronaphtho[2,1-b]furans from 2-Naphthols
1245
Table 2 (continued)
Product
1H NMR (CDCl3/TMS)
δ, J (Hz)
13C NMR (CDCl3/TMS)
δ
6
3.11 (m, 2H, ArCH2), 5.50 (dd, 1H, J = 6.8, 9.3, HCO), 7.15
(d, 1H, J = 8.8, Harom), 7.42 (m, 1H, Harom), 7.54 (d, 2H, J = 3.5,
37.0 (CH2), 70.9 (CH), 114.1 (CH), 118.1 (C), 120.5 (C),
125.0 (CH), 126.3 (CH), 129.6 (CH), 131.2 (CH), 132.4
(C), 132.5 (C), 132.9 (CH), 157.8 (C).
Harom), 7.74 (d, 1H, J = 8.8, Harom), 7.85 (d, 1H, J = 7.5, Harom
)
7
8
9
2.24 (s, 3H, CH3), 3.54 (m, 2H, ArCH2), 5.11 (m, 1H, HCO),
7.13 (d, 1H, J = 8.8, Harom), 7.27 (t, 1H, J = 8.1, Harom), 7.44
26.1 (CH3), 31.8 (CH2), 86.3 (CH), 112.7 (CH), 117.1 (C),
122.7 (CH), 123.3 (CH), 126.9 (CH), 128.6 (CH), 129.4
(C), 129.8 (C), 130.4 (CH), 156.4 (C) , 208.6 (C=O)
(m, 2H, Harom), 7.63 (d, 1H, J = 8.8, Harom), 7.74 (d, 1H, J = 8.1,
Harom
)
7.51 (dd, 1H, J = 1.3, 7.8, Harom), 7.53 (td, 1H, J = 1.3, 7.2,
Harom), 7.62 (td, 1H, J = 1.3, 7.2, Harom), 7.70 (d, 1H, J = 0.6,
=CH), 7.80 (d, 1H, J = 9.1, Harom), 7.88 (d, 1H, J = 7.8, Harom),
111.8 (CH), 111.8 (C), 116.9 (CH), 121.1 (C), 122.9 (CH),
125.7 (CH), 126.1 (C), 126.9 (C), 127.5 (CH), 128.8 (CH),
129.7 (CH), 130.2 (C), 157.5 (C)
7.97 (d, 1H, J = 7.8, Harom
)
2.66 (s, 3H, CH3), 7.56 (td, 1H, J = 1.2, 7.5, Harom), 7.60–7.70
(m, 2H, Harom), 7.88 (d, 1H, J = 9.1, Harom), 7.95 (s, 1H, CH),
26.3 (CH3), 112.4 (CH), 113.1 (CH), 123.3 (C), 123.7
(CH), 125.9 (CH), 127.8 (CH), 128.5 (C), 129.4 (CH),
130.3 (CH), 130.9 (C), 152. 7 (C), 154.4 (C), 188.4 (C=O)
7.96 (d, 1H, J = 7.1, Harom), 8,14 (d, 1H, J = 7.1, Harom
)
Lhoste, P.; Massacret, M.; Sinou, D. Bull. Soc. Chim. Fr.
1997, 134, 343.
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Acknowledgement
Financial support of this work by ADIR is gratefully acknowledged.
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Article Identifier:
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Synthesis 1999, No. 7, 1241–1245 ISSN 0039-7881 © Thieme Stuttgart · New York