Efficient allylation of 4-silyloxyquinolinium triflates and other positively charged heteroaromatic systems

Article abstract of DOI:10.1016/S0040-4020(00)01066-8

The regioselective allylation of 4-silyloxyquinolinium triflates with allyltri-n-butyltin has been performed to give 2-allyl-4-silyloxy-1,2-dihydroquinolines with excellent yields. Similiar results have been obtained with 4-silyloxy-1-benzopyrylium triflates and 4-silyloxy-1-benzothiopyrylium triflates.

Full text of DOI:10.1016/S0040-4020(00)01066-8

TETRAHEDRON
Pergamon
Tetrahedron 57 (2001) 1005±1013
Ef®cient allylation of 4-silyloxyquinolinium tri¯ates and other
positively charged heteroaromatic systems
Uwe Beifuss,a,p Ursula Schniskeb and Gerald Federa
a
È
È
È
È
Institut fur Organische Chemie der Georg-August-Universitat Gottingen, Tammannstr. 2, D-37077 Gottingen, Germany
b
È È È
Laboratorium fur Organische Chemie der Universitat Bayreuth, Universitatsstr. 30, D-95447 Bayreuth, Germany
Received 4 October 2000; accepted 8 November 2000
AbstractÐThe regioselective allylation of 4-silyloxyquinolinium tri¯ates with allyltri-n-butyltin has been performed to give 2-allyl-4-
silyloxy-1,2-dihydroquinolines with excellent yields. Similiar results have been obtained with 4-silyloxy-1-benzopyrylium tri¯ates and
4-silyloxy-1-benzothiopyrylium tri¯ates. q 2001 Elsevier Science Ltd. All rights reserved.
The 1,2-addition of allylic organometallic reagents to alde-
hydes, ketones and imines is one of the most important
CZC bond-forming reactions as the allyl group represents
a versatile functional carbon substituent.1 This is why
numerous protocols for this transformation have been
developed. In most cases Lewis acids have been employed
as activating reagents, because allylations without acti-
vation do not proceed under mild conditions.2 In com-
parison, fewer conjugate additions of allylic organo-
metallic reagents have been reported1,3 and the conjugate
addition to non activated vinylogous lactones, thiolactones
and lactams remains almost unexplored.4 An alternative is
the use of double-activated Michael acceptors.5 The allyl-
ation of azaaromatics is of great importance for the syn-
thesis of biologically active nitrogen compounds,
including alkaloids. Here the activation typically is
achieved by use of the corresponding N-acyliminium salts
that can be produced by reaction of the azaaromatics with
acyl chlorides.6 Using this approach, however, the allylation
of vinylogous lactams like 4-quinolones cannot be achieved.
heterocyclic vinylogous carbonyl compounds 1 is based on
the 1,2-addition of nucleophiles to the corresponding 4-silyl-
oxy substituted positively charged heteroaromatic systems 2
(Scheme 1). They can be prepared in situ and exhibit both a
reactive CyX1 bond and a silyl enol ether. Due to the
masking of the CyO group as a silyl enol ether, nucleophiles
exclusively add to the CyX1 bond to yield the 2-substituted
silyl enol ethers 3 selectively. The silyl enol ethers can
either be isolated or further transformed. Using this
methodology the regioselective 1,2-addition of enamines,7a
organolithium and organomagnesium reagents7b to 4-silyl-
oxyquinolinium tri¯ates has been reported to deliver the
conjugate addition products without any side products. In
addition it has been found that 4-silyloxyquinolinium
tri¯ates can be annulated in a highly regio- and diastereo-
selective manner employing 2-silyloxybuta-1,3-dienes7c,d
and 2-aminobuta-1,3-dienes.7a Similar results have been
obtained with 4-silyloxy-1-benzothiopyrylium tri¯ates.8
Here we report the regioselective allylation of several
positively charged 4-silyloxy-substituted heteroaromatics
corresponding to the conjugate allylation of vinylogous
lactams, lactones and thiolactones (Scheme 2).
Our concept for the conjugate addition of nucleophiles to
Scheme 1.
Keywords: allylation; quinolines; benzopyrans; sulfur heterocycles; tin and compounds; silicon and compounds.
Corresponding author. Tel.: 149-551-39-3253; fax: 149-551-39-9660; e-mail: ubeifus@gwdg.de
p
0040±4020/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)01066-8

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U. Beifuss et al. / Tetrahedron 57 (2001) 1005±1013
Scheme 2.
First the allylation of 4-silyloxyquinolinium tri¯ates 5a±e
was investigated, easily obtained in situ by reaction of the
N-protected 4-quinolones 4a,b with a tri¯uoromethane-
sulfonic acid trialkylsilyl ester under mild conditions.7
Treatment of the N-benzyloxycarbonyl- as well as the
N-ethoxycarbonyl protected quinolinium tri¯ates 5a±e
with 1.3 equiv. allyltri-n-butyltin at room temperature
gave the 2-allyl-4-silyloxy-1,2-dihydroquinolines 6a±e as
single products in high yields (Table 1, Entries 1±5). It
was found that this transformation can be performed with
tri¯uoromethanesulfonic acid trialkyl silyl esters like
lones, but can be used for the selective allylation of vinyl-
ogous lactones and thiolactones like 4g and 4h, too. The
structure of all products 6a±k was established by NMR
spectroscopy.
trimethylsilyl
tri¯uoromethanesulfonate
(TMSOTf),
triethylsilyl tri¯uoromethanesulfonate (TESOTf) and tri-
iso-propylsilyl tri¯uoromethanesulfonate (TIPSOTf).9 In
almost all cases the addition products could be isolated
and puri®ed without any dif®culties by ¯ash chroma-
tography. The only exception was the reaction of the
trimethylsilyloxy derivative 5a; here, the resulting
trimethylsilyl enol ether 6a undergoes partial hydrolysis to
the corresponding 2-allyl tetrahydroquinolone 7a upon
isolation and puri®cation (Table 1, Entry 1). Tetrahydro-
quinolones 7 can also be obtained by hydrolysis of the
corresponding tri-iso-propylsilyl ethers. As an example,
treatment of 6d with 2 N sulfuric acid affords the tetra-
hydroquinolone 7a in 70% yield. Allyltrimethylsilane,
which has been widely used as an allylating reagent1 does
not react with 5a±i under a variety of reaction conditions,
indicating that allylic silicon reagents are not suf®ciently
nucleophilic to react with a 4-silyloxy quinoliniumtri¯ate.10
Also, exclusive a-functionalization and high yields were
observed with the allylation of 4-silyloxy-1-benzopyrylium-
and 4-silyloxy-1-benzothiopyrylium tri¯ates 5j and 5k
(Table 1, Entries 10, 11). These results show that this
method is not restricted to the functionalization of 4-quino-
Martinellic acid (8) and related compounds are of great
interest in the ®eld of medicinal chemistry as they represent
the ®rst nonpeptide natural products that have been identi-
®ed as bradykinin receptor antagonists.11 In connection with
studies towards the synthesis of 8 the allylation with
6-substituted 4-quinolones like 4c±f was investigated.
Again, the regioselective allylation occurred and the corre-
sponding 2-allylated 1,2-dihydroquinolines 6f±i could be
isolated in yields from 78±90% (Table 1, Entries 6±9).
The silyl enol ether functionality in 6 offers numerous
perspectives for further functionalization at C-3 and C-4.
Preliminary experiments show that treatment of 6a and 6b
with N-bromosuccinimide (NBS) at 2788C proceeds
diastereoselectively as only the 2,3-trans-disubstituted
compound 9 was formed. With respect to the synthesis of
8 further studies will concentrate on radical transformations
of 9 as well as reactions of silyl enol ethers 6 with C-elec-
trophiles.
Table 1. The allylation of 4-silyloxy substituted positively charged hetero-
aromatics 5
Entry
4
X
R1
5
R2
6
Yield 6 [%]
1
2
3
4
5
6
7
8
a
a
b
a
b
c
d
e
f
N-CO2Bn
N-CO2Bn
N-CO2Et
N-CO2Bn
N-CO2Et
N-CO2Bn
N-CO2Et
N-CO2Bn
N-CO2Et
O
H
H
H
H
a
b
c
d
e
f
g
h
i
Me3
Et3
Et3
a
b
c
d
e
f
g
h
i
52a
88
94
80
86
84
90
78
90
86
91
(i-Pr)3
(i-Pr)3
(i-Pr)3
(i-Pr)3
(i-Pr)3
(i-Pr)3
(i-Pr)3
(i-Pr)3
H
Br
Br
CO2Bn
CO2Bn
H
9
10
11
g
h
j
k
j
k
S
H
a Due to its hydrolytic instability, 6a could not be obtained analytically
pure. Besides 6a, 28% of the corresponding tetrahydroquinolone 7a was
isolated.
The assignment of the stereochemistry of 9 is mainly based
on 1H NMR spectroscopy. 3H resonates at dˆ4.39 ppm as a

U. Beifuss et al. / Tetrahedron 57 (2001) 1005±1013
1007
Scheme 3.
doublet with a coupling constant of Jˆ2.0 Hz (3J2,3ˆ
2.0 Hz): The small value for this vicinal coupling constant
proves the trans-arrangement of the substituents at C-2 and
C-3. The assignment ®nds support from the results of
the X-ray crystal structure analysis of some related com-
pounds.12
further puri®cation or prepared by standard methods: ¯ash
chromatography, silica gel 60 (0.040±0.063 mm), Merck;
TLC, silica gel 60 F254 glass plates, Merck [compounds
were visualized by conc. H2SO4 (1808C, 5 min)]; melting
points (uncorrected), BuÈchi 510; UV, Perkin±Elmer
Lambda 9 or Shimadzu 160 A; IR, Perkin±Elmer Paragon
1000 FT IR spectrometer or Bruker IFS 25 FTIR spectro-
1
The N-protected 4-quinolones 4a,b are easily accessible by
protection of 4-quinolone 4i (XˆNH) using standard pro-
cedures.13 6-Bromo-4-quinolone (11a) and 6-benzyloxy-
carbonyl-4-quinolone (11b) were synthesized according to
the procedure of Valderrama employing 4-bromoaniline
(12a) and 4-benzyloxycarbonylaniline (12b) as starting
materials.14 The reaction of the para-substituted anilines
12 with Meldrum's acid (13) and methyl orthoformate
(14) gave the corresponding arylaminomethylene
Meldrum's derivatives 10a,b, that in turn were heated in
boiling diphenyl ether to deliver 11a and 11b with high
yields. 11a and 11b were transformed into the N-protected
4-quinolones 4c±f employing standard procedures (Scheme
3).13
meter; H and 13C NMR, Jeol JNM-EX 270 or Bruker AM-
500-FT; d in ppm calibrated to residual solvent signal with
chemical shifts referred to TMS (0.00 ppm); J in [Hz]; * assign-
ments interchangeable; MS, MAT 312 mass spectrometer;
combustion analyses, Microanalytical Laboratory of the Institut
È È
fuÈr Organische Chemie der Universitat Gottingen.
1.1.1. General procedure for the allylation of 4. If not
stated otherwise 1.3 equiv. TIPSOTf was added dropwise
to 1.0 equiv. 4 and the mixture was held at room tempera-
ture for 1 h under argon. After the successive addition of dry
dichloromethane (2 ml/1.0 mmol 4), 1.3 equiv. 2,6-lutidine
and 1.3 equiv. allyltri-n-butyltin at 08C the resulting solu-
tion was stirred for 3 h at room temperature. The reaction
mixture was poured into icecold 5% aqueous potassium
hydrogen carbonate (20 ml/1.0 mmol 4), and extracted
with cold dichloromethane (3£30 ml/1.0 mmol 4). The
combined organic phases were dried over magnesium sul-
fate and the solvent was removed at reduced pressure on a
rotary evaporator. Finally the crude product was puri®ed by
¯ash chromatography on silica gel.
To summarize, we have presented the ®rst examples for the
conjugate addition of allylstannanes to 4-quinolones. The
new method relies on the ef®cient addition of allyltri-n-
butyltin to 4-silyloxy quinolinium tri¯ates, that are obtained
from the corresponding 4-quinolones in situ. The allylation
products are envisioned to be ideal building blocks for
synthesizing biologically important molecules such as
martinellic acid (8) and pumiliotoxin C. In addition it was
shown, that the allylations are not restricted to 4-quinolones,
but can be performed with 4-benzopyranones and 4-benzo-
thiopyranones, too.
1.1.2. 1-Benzyloxycarbonyl-2-(2-propenyl)-4-trimethyl
silyloxy-2H-quinoline (6a). Reaction of 0.40 g (1.43
mmol) 4a with 0.34 ml (1.76 mmol) TMSOTf, 0.22 ml
(1.89 mmol) 2,6-lutidine and 0.58 ml (1.87 mmol) allyltri-
n-butyltin according to the General Procedure yielded after
¯ash chromatography on 95 g silica gel (cyclohexane/
diethyl etherˆ14:1) 0.13 g (28%) 7a and 0.29 g (52%) 6a
as a colourless and sensitive oil. Rfˆ0.32 (cyclohexane/
1. Experimental
1
diethyl etherˆ9:1). H NMR (270 MHz, CDCl3): dˆ0.24
1.1. Methods and materials
3
[s, 9H, Si(CH3)3], 2.17 (t, Jˆ6.5 Hz, 2H, CH2CHyCH2),
3
4.85±5.00 (m, 2H, CH2CHyCH2), 5.06 (q, Jˆ6.5 Hz, 1H,
All solvents were distilled prior to use. CH2Cl2 was dried
over basic alumina. Reagents and materials were either
obtained from commercial suppliers and used without
2H), 5.18 (d, 3Jˆ6.5 Hz, 1H, 3H), 5.19 (d, 2Jˆ12.0 Hz, 1H,
CO2CHaHC6H5), 5.26 (d, 2Jˆ12.0 Hz, 1H, CO2CHHbC6H5),

1008
U. Beifuss et al. / Tetrahedron 57 (2001) 1005±1013
5.70 (mc, 1H, CH2CHyCH2), 7.08 (dt, 4Jˆ1.5 Hz, 3Jˆ
according to the General Procedure yielded after ¯ash
chromatography on 95 g silica gel (cyclohexane/diethyl
etherˆ9:1) 0.55 g (88%) 6b as a colourless oil. Rfˆ0.43
,
7.5 Hz, 1H, 6H), 7.15±7.26 (m, 1H, 7H), 7.28±7.39 (m,
4
3
5H, 20H, 30H, 40H, 50H, 60H), 7.42 (dd, Jˆ1.5 Hz, Jˆ
7.5 Hz, 1H, 5H), 7.48±7.62 (br, 1H, 8H). 13C NMR
(cyclohexane/diethyl etherˆ9:1) IR (CCl4): nˆ3074 cm21
(68 MHz,
CDCl3):
dˆ0.08
[Si(CH3)3],
38.73
3035 (arom. CH, CyCH); 2958, 2912, 2877 (CH); 1705
(CyO); 1646 (CyC); 1488; 1456; 1395; 1355; 1320;
1245. UV (acetonitrile): lmax (log e)ˆ240 nm (4.39), 270
(3.76). 1H NMR (270 MHz, CDCl3): dˆ0.73 (q, 3Jˆ8.0 Hz,
6H, 3£CH2CH3), 0.98 (t, 3Jˆ8.0 Hz, 9H, 3£CH2CH3), 2.16
(t, 3Jˆ7.0 Hz, 2H, CH2CHyCH2), 4.85±5.00 (m, 2H,
(CH2CHyCH2), 52.23 (C-2), 67.55 (CO2CH2C6H5),
106.12 (C-3), 117.59 (CH2CHyCH2), 122.25 (C-8),
122.46 (C-6), 123.86 (C-5), 126.31 (C-4a), 127.82 (C-30,
C-50)*, 127.91 (C-7), 128.01 (C-40), 128.45 (C-20, C-60)*,
133.87 (CH2CHyCH2), 134.24 (C-4), 136.21 (C-10), 145.82
(C-8a), 153.94 (CO2CH2C6H5).
3
3
CH2CHyCH2), 5.06 (q, Jˆ7.0 Hz, 1H, 2H), 5.17 (d, Jˆ
7.0 Hz, 1H, 3H), 5.19 (d, 2Jˆ12.5 Hz, 1H, CO2CHaHC6H5),
2
1.1.3. 1-Benzyloxycarbonyl-2-(2-propenyl)-4-oxo-1,2,3,4-
tetrahydroquinoline (7a). 0.84 ml (4.34 mmol) TMSOTf
was added dropwise to 1.00 g (3.58 mmol) 4a and the
mixture was held at room temperature for 1 h under
argon. After successive addition of 7.5 ml dry dichloro-
methane, 0.54 ml (4.64 mmol) 2,6-lutidine and 1.44 ml
(4.64 mmol) allyltri-n-butyltin at 08C the resulting solution
was stirred for 3 h at room temperature. The reaction
mixture was poured into 60 ml ice-cold 5% aqueous potas-
sium hydrogen carbonate and extracted with cold dichloro-
methane (3£80 ml). The organic phases were combined and
the solvent was removed at reduced pressure on a rotary
evaporator. The combined organic phases were dried over
magnesium sulfate and the solvent was removed. The resi-
due was dissolved in 15 ml THF and treated with 10 ml 10%
sulfuric acid. After stirring for 2 h at room temperature the
reaction mixture was extracted with diethyl ether (3£80 ml).
The combined organic phases were dried over magnesium
sulfate and the solvent was removed. Puri®cation of the
crude product by ¯ash chromatography on 95 g silica gel
(cyclohexane/ethyl acetateˆ6:1) afforded 0.81 g (70%) 7a
as a colourless oil. Rfˆ0.31 (cyclohexane/ethyl acetateˆ
4:1). IR (CCl4): nˆ3078 cm21, 3035 (arom. CH, CyCH);
2927, 2851 (CH); 1711 (CyO, carbamate); 1693 (CyO);
1603 (CyC); 1480; 1460; 1390; 1336; 1320; 1302; 1288;
1260; 1226. UV (acetonitrile): lmax (log e)ˆ234 nm (4.49),
258 (4.03), 325 (3.56). 1H NMR (270 MHz, CDCl3):
dˆ2.14±2.40 (m, 2H, CH2CHyCH2), 2.66 (dd, 3Jˆ
5.26 (d, Jˆ12.5 Hz, 1H, CO2CHHbC6H5), 5.71 (mc, 1H,
4
3
CH2CHyCH2), 7.09 (dt, Jˆ1.0 Hz, Jˆ7.5 Hz, 1H, 6H),
4
3
7.22 (dt, Jˆ1.5 Hz, Jˆ7.5 Hz, 1H, 7H), 7.27±7.37 (m,
4
3
5H, 20H, 30H, 40H, 50H, 60H), 7.48 (dd, Jˆ1.5 Hz, Jˆ
7.5 Hz, 1H, 5H), 7.50±7.58 (br, 1H, 8H). 13C NMR
(68 MHz, CDCl3): dˆ4.93 (3£CH2CH3), 6.68 (3£
CH2CH3), 38.70 (CH2CHyCH2), 52.26 (C-2), 67.55
(CO2CH2C6H5), 105.37 (C-3), 117.55 (CH2CHyCH2),
122.25 (C-8), 123.94 (C-6), 124.37 (C-5), 126.46 (C-4a),
127.81 (C-30, C-50)*, 127.89 (C-7), 128.02 (C-40), 128.47
(C-20, C-60)*, 133.98 (CH2CHyCH2), 134.96 (C-4), 136.28
(C-10), 146.02 (C-8a), 153.98 (CO2CH2C6H5). MS (70 eV);
m/z (%): 394 (53) [M1-C3H5], 350 (83) [394-CO2], 261 (12),
230 (12), 91 (100) [C7H17 ]. Anal. calcd. for C26H33NO3Si
(435.64): C, 71.68; H, 7.63; N 3.22: Found: C, 71.87; H,
7.84; N, 3.14.
1.1.5. 1-Ethoxycarbonyl-2-(2-propenyl)-4-triethyl silyl-
oxy-2H-quinoline (6c). Reaction of 1.2 g (5.52 mmol) 4b
with 1.62 ml (7.16 mmol) TESOTf, 0.84 ml (7.21 mmol)
2,6-lutidine and 2.23 ml (7.19 mmol) allyltri-n-butyltin
according to the General Procedure yielded after ¯ash
chromatography on 95 g silica gel (cyclohexane/diethyl
etherˆ9:1) 1.93 g (94%) 6c as a colourless oil. Rfˆ0.32
(cyclohexane/diethyl etherˆ9:1). IR (CCl4): nˆ
3076 cm21, 3026 (arom. CH, CyCH); 2958, 2911, 2877
(CH); 1700 (CyO); 1646 (CyC); 1488; 1456; 1399; 1356;
1320; 1242. UV (acetonitrile): lmax (log e)ˆ240 nm (4.42),
274 (3.79). 1H NMR (270 MHz, CDCl3): dˆ0.73 (q,
3Jˆ8.0 Hz, 6H, 3£ CH2CH3), 0.98 (t, 3Jˆ8.0 Hz, 9H,
2
3
2
1.5 Hz, Jˆ17.5 Hz, 1H, 3Ha), 3.01 (dd, Jˆ6.0 Hz, Jˆ
17.5 Hz, 1H, 3Hb), 4.86 (dd, 2Jˆ1.5 Hz, 3Jˆ17.0 Hz,
1H, CH2CHyCHH(trans)), 4.96±5.10 (m, 2H, 2H,
CH2CHyCHH(cis)), 5.24±5.35 (m, 2H, CO2CH2C6H5),
5.69 (mc, 1H, CH2CHyCH2), 7.16 (dt, 4Jˆ1.0 Hz, 3Jˆ
8.0 Hz, 1H, 6H), 7.30±7.40 (m, 5H, 20H, 30H, 40H, 50H,
3
3£CH2CH3), 1.28 (t, Jˆ7.0 Hz, 3H, CO2CH2CH3), 2.16
(t, 3Jˆ6.5 Hz, 2H, CH2CHyCH2), 4.12±4.32 (m, 2H,
CO2CH2CH3), 4.86±5.00 (m, 2H, CH2CHyCH2), 5.03 (q,
3Jˆ6.5 Hz, 1H, 2H), 5.17 (d, 3Jˆ6.5 Hz, 1H, 3H), 5.73 (mc,
4
3
4
3
60H), 7.49 (dt, Jˆ1.5 Hz, Jˆ8.0 Hz, 1H, 7H), 7.76 (dbr,
1H, CH2CHyCH2), 7.08 (dt, Jˆ1.0 Hz, Jˆ7.5 Hz, 1H,
3Jˆ8.0 Hz, 1H, 8H), 7.97 (dd, Jˆ1.5 Hz, Jˆ8.0 Hz, 1H,
5H). 13C NMR (68 MHz, CDCl3): dˆ36.07 (CH2CHyCH2),
42.52 (C-3), 53.39 (C-2), 68.19 (CO2CH2C6H5), 118.43
(CH2CHyCH2), 124.19, 124.66 (C-8, C-6), 124.87 (C-4a),
126.63 (C-5), 128.08 (C-30, C-50)*, 128.39 (C-40), 128.63
(C-20, C-60)*, 133.37 (CH2CHyCH2), 134.47 (C-7), 135.73
(C-10), 140.91 (C-8a), 153.94 (CO2CH2C6H5), 193.02 (C-4).
MS (70 eV); m/z (%): 321 (4) [M1], 280 (33) [M1-C3H5],
236 (30) [280-CO2], 146 (6), 91 (100) [C7H17 ], 65 (18)
[C5H15 ]. Anal. calcd. for C20H19NO3 (321.37): C, 74.75;
H, 5.96; N, 4.36. Found: C, 74.60; H, 5.81; N 4.38.
6H), 7.22 (dt, Jˆ1.5 Hz, Jˆ7.5 Hz, 1H, 7H), 7.47 (dd,
4
3
4
3
3
4Jˆ1.5 Hz, Jˆ7.5 Hz, 1H, 5H), 7.42±7.57 (br, 1H, 8H).
13C NMR (68 MHz, CDCl3): dˆ4.95 (3£CH2CH3), 6.69
(3£ CH2CH3), 14.46 (CO2CH2CH3), 38.75 (CH2CHyCH2),
52.06 (C-2), 61.91 (CO2CH2CH3), 105.42 (C-3), 117.43
(CH2CHyCH2), 122.22 (C-8), 123.72 (C-6), 124.31 (C-5),
126.40 (C-4a), 127.81 (C-7), 134.06 (CH2CHyCH2), 135.17
(C-4), 145.99 (C-8a), 154.18 (CO2CH2CH3). MS (70 eV);
m/z (%): 373 (1) [M1], 332 (100) [M1-C3H5], 288 (20) [332
CO2], 260 (59) [288-C2H4], 230 (20), 172 (14), 87 (42), 59
(11), 32 (11). Anal. calcd. for C21H31NO3Si (373.57): C,
67.52; H, 8.36; N, 3.75. Found: C, 67.77; H, 8.51; N, 3.69.
1.1.4. 1-Benzyloxycarbonyl-2-(2-propenyl)-4-triethyl silyl-
oxy-2H-quinoline (6b). Reaction of 0.40 g (1.43 mmol) 4a
with 0.42 ml (1.86 mmol) TESOTf, 0.22 ml (1.89 mmol)
2,6-lutidine and 0.58 ml (1.87 mmol) allyltri-n-butyltin
1.1.6. 1-Benzyloxycarbonyl-2-(2-propenyl)-4-tri-iso-propyl
silyloxy-2H-quinoline (6d). Reaction of 0.46 g (1.65 mmol)
4a with 0.45 ml (1.67 mmol) TIPSOTf, 0.20 ml (1.72 mmol)

U. Beifuss et al. / Tetrahedron 57 (2001) 1005±1013
1009
2,6-lutidine and 0.66 ml (2.13 mmol) allyltri-n-butyltin
according to the General Procedure yielded after ¯ash chro-
matography on 95 g silica gel (cyclohexane/diethyl etherˆ
9:1) 0.63 g (80%) 6d as a colourless oil. Rfˆ0.38 (cyclo-
hexane/diethyl etherˆ9:1). IR (CCl4): nˆ3075 cm21, 3035
(arom. CH, CyCH); 2945, 2893, 2867 (CH); 1705 (CyO);
1644 (CyC); 1488; 1463; 1455; 1395; 1353; 1320; 1245.
UV (acetonitrile): lmax (log e)ˆ240 nm (4.33), 274 (3.77).
0.30 g (0.84 mmol) 4c with 0.29 ml (1.08 mmol) TIPSOTf,
0.13 ml (1.12 mmol) 2,6-lutidine and 0.34 ml (1.10 mmol)
allyltri-n-butyltin according to the General Procedure
yielded after ¯ash chromatography on 95 g silica gel (cyclo-
hexane/diethyl etherˆ14:1) 0.39 g (84%) 6f as a colourless
oil. Rfˆ0.45 (cyclohexane/diethyl etherˆ9:1). IR (CCl4):
nˆ3072 cm21, 3030 (arom. CH, CyCH); 2946, 2881,
2867 (CH); 1710 (CyO); 1646 (CyC); 1482; 1394; 1342;
1310; 1244. UV (acetonitrile): lmax (log e)ˆ247 nm (4.44).
3
1H NMR (270 MHz, CDCl3): dˆ1.10 [d, Jˆ7.0 Hz, 18H,
3
3£CH(CH3)2], 1.18±1.35 [m, 3H, 3£CH(CH3)2], 2.17 (t,
3Jˆ6.5 Hz, 2H, CH2CHyCH2), 4.86±5.00 (m, 2H,
CH2CHyCH2), 5.07 (q, 3Jˆ6.5 Hz, 1H, 2H), 5.18 (d,
3Jˆ6.5 Hz, 1H, 3H), 5.21 (d, 2Jˆ12.5 Hz, 1H,
1H NMR (270 MHz, CDCl3): dˆ1.09 [d, Jˆ6.5 Hz, 18H,
3£CH(CH3)2], 1.18±1.32 [m, 3H, 3£CH(CH3)2], 2.12±2.17
(m, 2H, CH2CHyCH2), 4.83±5.00 (m, 2H, CH2CHyCH2),
3
3
5.05 (q, Jˆ6.5 Hz, 1H, 2H), 5.18 (d, Jˆ6.5 Hz, 1H, 3H),
5.19±5.30 (m, 2H, CO2CH2C6H5), 5.68 (mc, 1H,
CH2CHyCH2), 7.26±7.46 (m, 7H, 20H, 30H, 40H, 50H,
2
CO2CHaHC6H5), 5.27 (d, Jˆ12.5 Hz, 1H, CO2CHHbC6H5),
5.72 (mc, 1H, CH2CHyCH2), 7.10 (dt, 4Jˆ1.0 Hz, 3Jˆ7.5 Hz,
1H, 6H), 7.22 (dt, 4Jˆ1.5 Hz, 3Jˆ7.5 Hz, 1H, 7H), 7.27±7.38
(m, 5H, 20H, 30H, 40H, 50H, 60H), 7.42±7.58 (br, 1H, 8H),
7.56 (dd, 4Jˆ1.5 Hz, 3Jˆ7.5 Hz, 1H, 5H). 13C NMR (68 MHz,
CDCl3): dˆ12.71 [3£CH(CH3)2], 18.02, 18.06 [3£CH(CH3)2],
38.66 (CH2CHyCH2), 52.27 (C-2), 67.53 (CO2CH2C6H5),
104.86 (C-3), 117.53 (CH2CHyCH2), 122.42 (C-8), 123.98
(C-6), 124.41 (C-5), 126.63 (C-4a), 127.78 (C-30, C-50)*,
127.99 (C-7), 128.46 (C-20, C-40, C-60)*, 134.00
(CH2CHyCH2), 134.95 (C-4), 136.29 (C-10), 146.26 (C-8a),
153.97 (CO2CH2C6H5). MS (70 eV); m/z (%): 436 (74) [M1-
C3H5], 392 (100) [436-CO2], 258 (10), 202 (12), 188 (7), 172
(6), 91 (98) [C7H71]. Anal. calcd. for C29H39NO3Si (477.72):
C, 72.91; H 8.23. Found: C, 73.07; H, 8.50.
4
60H, 7H, 8H), 7.64 (d, Jˆ2.5 Hz, 1H, 5H). 13C NMR
(68 MHz, CDCl3): dˆ12.67 [3£CH(CH3)2], 18.00, 18.03
[3£CH(CH3)2], 38.80 (CH2CHyCH2), 52.29 (C-2), 67.78
(CO2CH2C6H5), 105.71 (C-3), 117.14 (C-6), 117.82
(CH2CHyCH2), 125.44 (C-8), 125.96 (C-5), 127.89 (C-30,
C-50)*, 128.17 (C-40), 128.44 (C-4a), 128.55 (C-20, C-60)*,
130.61 (C-7), 133.67 (CH2CHyCH2), 134.03 (C-4), 136.02
(C-10), 145.25 (C-8a), 153.73 (CO2CH2C6H5). MS (70 eV);
m/z (%): 516 (8) [M1-C3H5], 514 (8) [M1-C3H5], 472 (21)
[516-CO2], 470 (20) [514-CO2], 186 (7), 91 (100) [C7H17 ].
Anal. calcd. for C29H38BrNO3Si (556.61): C, 62.58; H, 6.88.
Found: C, 62.66; H, 6.85.
1.1.9. 6-Bromo-1-ethoxycarbonyl-2-(2-propenyl)-4-tri-
iso-propyl silyloxy-2H-quinoline (6g). Reaction of 0.30 g
(1.01 mmol) 4d with 0.36 ml (1.34 mmol) TIPSOTf,
0.15 ml (1.29 mmol) 2,6-lutidine and 0.41 ml (1.32 mmol)
allyltri-n-butyltin according to the General Procedure
yielded after ¯ash chromatography on 95 g silica gel (cyclo-
hexane/diethyl etherˆ9:1) 0.45 g (90%) 6g as a colourless
oil. Rfˆ0.38 (cyclohexane/diethyl etherˆ9:1). IR (CCl4):
nˆ3078 cm21 (arom. CH, CyCH); 2946, 2882, 2868
(CH); 1707 (CyO); 1642 (CyC); 1482; 1397; 1342; 1311;
1.1.7. 1-Ethoxycarbonyl-2-(2-propenyl)-4-tri-iso-propyl
silyloxy-2H-quinoline (6e). Reaction of 0.40 g (1.84
mmol) 4b with 0.50 ml (1.85 mmol) TIPSOTf, 0.22 ml
(1.89 mmol) 2,6-lutidine and 0.74 ml (2.39 mmol) allyltri-
n-butyltin according to the General Procedure yielded after
¯ash chromatography on 95 g silica gel (cyclohexane/
diethyl etherˆ9:1) 0.66 g (86%) 6e as a colourless oil.
Rfˆ0.29 (cyclohexane/diethyl etherˆ9:1). IR (CCl4): nˆ
3077 cm21 (arom. CH, CyCH); 2945, 2881, 2867 (CH);
1703 (CyO); 1644 (CyC); 1488; 1463; 1399; 1354; 1320;
1246. UV (acetonitrile): lmax (log e)ˆ240 nm (4.33), 270
(3.69). 1H NMR (270 MHz, CDCl3): dˆ1.10 [d, 3Jˆ6.5 Hz,
18H, 3£CH(CH3)2], 1.18±1.33 [m, 6H, 3£CH(CH3)2,
1
1244. UV (acetonitrile): lmax (log e)ˆ247 nm (4.35). H
3
NMR (270 MHz, CDCl3): dˆ1.10 [d, Jˆ6.5 Hz, 18H, 3£
CH(CH3)2], 1.18±1.35 [m, 6H, 3£CH(CH3)2, CH2CH3],
2.11±2.17 (m, 2H, CH2CHyCH2), 4.12±4.29 (m, 2H,
CH2CH3), 4.84±5.09 (m, 3H, 2H, CH2CHyCH2), 5.19 (d,
3Jˆ6.5 Hz, 1H, 3H), 5.70 (mc, 1H, CH2CHyCH2), 7.32 (dd,
3
CH2CH3], 2.16 (t, Jˆ6.5 Hz, CH2CHyCH2), 4.16±4.35
(m, 2H, CH2CH3), 4.87±5.00 (m, 2H, CH2CHyCH2), 5.04
3
3
3
(q, Jˆ6.5 Hz, 1H, 2H), 5.17 (d, Jˆ6.5 Hz, 1H, 3H), 5.72
4Jˆ2.0 Hz, Jˆ8.5 Hz, 1H, 7H), 7.36±7.46 (br, 1H, 8H),
4
3
4
(mc, 1H, CH2CHyCH2), 7.09 (dt, Jˆ1.0 Hz, Jˆ6.0 Hz,
7.64 (d, Jˆ2.0 Hz, 1H, 5H). 13C NMR (68 MHz, CDCl3):
4
3
1H, 6H), 7.22 (dt, Jˆ1.0 Hz, Jˆ6.0 Hz, 1H, 7H), 7.46±
7.58 (br, 1H, 8H), 7.55 (dd, 4Jˆ1.0 Hz, 3Jˆ6.0 Hz, 1H, 5H).
13C NMR (68 MHz, CDCl3): dˆ12.69 [3£CH(CH3)2],
14.42 (CO2CH2CH3), 18.00, 18.04 [3£CH(CH3)2], 38.67
(CH2CHyCH2), 52.04 (C-2), 61.89 (CO2CH2CH3), 104.85
(C-3), 117.38 (CH2CHyCH2), 122.36 (C-8), 123.76 (C-6),
124.35 (C-5), 126.54 (C-4a), 127.72 (C-7), 134.06
(CH2CHyCH2), 135.12 (C-4), 146.20 (C-8a), 154.15
(CO2CH2CH3). MS (70 eV); m/z (%): 415 (3) [M1], 374
(100) [M1-C3H5], 330 (16) [374-CO2], 302 (17) [330-
C2H4], 258 (8) [M1 C9H21Si], 202 (8), 172 (7), 115 (6)
[C6H15Si1], 87 (7), 73 (7) [C3H9Si1], 59 (9). Anal. calcd.
for C24H37NO3Si (415.65): C, 69.35; H, 8.97; N, 3.37.
Found: C, 69.29; H, 8.89; N, 3.39.
dˆ12.63 [3£CH(CH3)2], 14.37 (CO2CH2CH3), 17.94, 17.97
[3£CH(CH3)2], 38.78 (CH2CHyCH2), 52.04 (C-2), 62.05
(CO2CH2CH3), 105.71 (C-3), 116.86 (C-6), 117.63
(CH2CHyCH2), 125.33 (C-8), 125.88 (C-5), 128.30
(C-4a), 130.48 (C-7), 133.66 (CH2CHyCH2), 134.20
(C-4), 145.17 (C-8a), 153.81 (CO2CH2CH3). MS (70 eV);
m/z (%): 454 (99) [M1-C3H5], 452 (100) [M1-C3H5], 410
(8) [454-CO2], 408 (8) [452-CO2], 382 (8) [410-C2H4], 380
(8) [408-C2H4], 338 (4) [M1-C9H21Si], 336 (4) [M1-
C9H21Si], 286 (4), 258 (6), 214 (4), 186 (10), 172 (5), 115
(11) [C6H15Si1], 87 (8), 73 (8) [C3H9Si1], 59 (13). Anal.
calcd. for C24H36BrNO3Si (494.54): C, 58.29; H, 7.34.
Found: C, 58.57; H, 7.38.
1.1.10.
1,6-Dibenzyloxycarbonyl-2-(2-propenyl)-4-tri-
1.1.8. 1-Benzyloxycarbonyl-6-bromo-2-(2-propenyl)-4-
tri-iso-propyl silyloxy-2H-quinoline (6f). Reaction of
iso-propyl silyloxy-2H-quinoline (6h). Reaction of 0.40 g
(0.97 mmol) 4e with 0.34 ml (1.26 mmol) TIPSOTf,

1010
U. Beifuss et al. / Tetrahedron 57 (2001) 1005±1013
0.15 ml (1.29 mmol) 2,6-lutidine and 0.39 ml (1.26 mmol)
allyltri-n-butyltin according to the General Procedure
yielded after ¯ash chromatography on 95 g silica gel (cyclo-
hexane/diethyl etherˆ9:1) 0.46 g (78%) 6h as a colourless
oil. Rfˆ0.26 (cyclohexane/diethyl etherˆ9:1). IR (CCl4):
nˆ 3067 cm21, 3034 (arom. CH, CyCH); 2946, 2892,
2867 (CH); 1717 (CyO); 1652 (CyC); 1491; 1456; 1394;
1351; 1302; 1280; 1232. UV (acetonitrile): lmax (log
e)ˆ261 nm (4.66), 293 (3.95). 1H NMR (500 MHz,
CDCl3): dˆ1.07 [d, 3Jˆ7.5 Hz, 18H, 3£CH(CH3)2],
1.20±1.30 [m, 3H, 3£CH(CH3)2], 2.11±2.21 (m, 2H,
CH2CHyCH2), 4.90 (ddd, 4Jˆ1.5 Hz, 2Jˆ2.0 Hz,
3Jˆ17.0 Hz, 1H, CH2CHyCHH(trans)), 4.96 (ddd, 4Jˆ
1.0 Hz, 2Jˆ2.0 Hz, 3Jˆ10.0 Hz, 1H, CH2CHyCHH(cis)),
(CH2CHyCH2), 136.04 (C-100), 139.65 (C-4), 145.63
(C-8a), 153.85 (CO2CH2CH3), 166.03 (CO2CH2C6H5). MS
(70 eV); m/z (%): 549 (1) [M1], 508 (100) [M1-C3H5], 464
(5) [508-CO2], 436 (6) [464-C2H4], 392 (5) [M1-C9H21Si],
374 (4), 91 (62) [C7H17 ], 59 (6). Anal. calcd. for
C32H43NO5Si (549.78): C, 69.91; H, 7.88; N, 2.55. Found:
C, 70.19; H, 7.95; N, 2.54.
1.1.12. 2-(2-Propenyl)-4-tri-iso-propylsilyloxy-2H-chro-
mene (6j). Reaction of 0.31 g (2.12 mmol) 4g with
0.58 ml (2.16 mmol) TIPSOTf, 0.25 ml (2.15 mmol) 2,6-
lutidine and 0.85 ml (2.74 mmol) allyltri-n-butyltin accord-
ing to the General Procedure yielded after ¯ash chromato-
graphy on 95 g silica gel (cyclohexane/diethyl etherˆ80:1)
0.63 g (86%) 6j as a colourless oil. Rfˆ0.41 (cyclohexane/
diethyl etherˆ80:1). IR (CCl4): nˆ3078 cm21, 3040 (arom.
CH, CyCH); 2945, 2893, 2867 (CH); 1646 (CyC); 1606;
1484; 1454; 1356; 1231. UV (acetonitrile): lmax (log
e)ˆ215 nm (4.27), 269 (3.51), 306 (3.62). 1H NMR
(270 MHz, CDCl3): dˆ1.11 [d, 3Jˆ7.0 Hz, 18H, 3£
CH(CH3)2], 1.18±1.32 [m, 3H, 3£CH(CH3)2], 2.34±2.61
3
3
5.07 (q, Jˆ6.5 Hz, 1H, 2H), 5.19 (d, Jˆ6.5 Hz, 1H, 3H),
5.22 (d, 2Jˆ12.5 Hz, 1H, NCO2CHaHC6H5), 5.26 (d,
2
2Jˆ12.5 Hz, 1H, NCO2CHHbC6H5), 5.31 (d, Jˆ12.5 Hz,
1H, CO2CHaHC6H5), 5.35 (d, 2Jˆ12.5 Hz, 1H,
CO2CHHbC6H5), 5.68 (mc, 1H, CH2CHyCH2), 7.29±7.43
(m, 10H, 20H, 30H, 40H, 50H, 60H, 200H, 300H, 400H, 500H,
600H), 7.62±7.71 (br, 1H, 8H), 7.94 (dd, 4Jˆ2.0 Hz,
3Jˆ8.5 Hz, 1H, 7H), 8.29 (d, 4Jˆ2.0 Hz, 1H, 5H). 13C
NMR (68 MHz, CDCl3): dˆ12.67 [3£CH(CH3)2], 17.97,
18.00 [3£CH(CH3)2], 39.25 (CH2CHyCH2), 52.64 (C-2),
66.65 (CO2CH2C6H5), 67.95 (NCO2CH2C6H5), 105.04
(C-3), 117.93 (CH2CHyCH2), 123.91 (C-8), 124.24 (C-5),
125.36 (C-6), 126.28 (C-4a), 127.96 (C-300, C-500)*, 128.14
(C-400)*, 128.18 (C-200, C-600)*, 128.24 (C-40)*, 128.53
(C-30, C-50)*, 128.57 (C-20, C-60)*, 129.44 (C-7), 133.52
(CH2CHyCH2), 135.84 (C-10)*, 136.03 (C-100)*, 139.43
(C-4), 145.66 (C-8a), 153.68 (NCO2CH2C6H5), 165.99
(CO2CH2C6H5). MS (70 eV); m/z (%): 570 (17) [M1-
C3H5], 526 (67) [570-CO2], 392 (8), 91 (100) [C7H17 ].
Anal. calcd. for C37H45NO5Si (611.85): C, 72.63; H, 7.41.
Found: C, 72.55; H, 7.33.
3
(m, 2H, CH2CHyCH2), 4.81 (d, Jˆ3.5 Hz, 1H, 3H), 4.95
3
3
(dt, Jˆ3.5 Hz, Jˆ6.5 Hz, 1H, 2H), 5.06±5.15 (m, 2H,
CH2CHyCH2), 5.77±5.94 (m, 1H, CH2CHyCH2), 6.76
4
3
4
(dd, Jˆ1.0 Hz, Jˆ7.5 Hz, 1H, 8H), 6.87 (dt, Jˆ1.0 Hz,
3Jˆ7.5 Hz, 1H, 6H), 7.12 (dt, Jˆ1.5 Hz, Jˆ7.5 Hz, 1H,
4
3
7H), 7.39 (dd, Jˆ1.5 Hz, Jˆ7.5 Hz, 1H, 5H). 13C NMR
(68 MHz, CDCl3): dˆ12.73 [3£CH(CH3)2], 18.04, 18.05
[3£CH(CH3)2], 40.72 (CH2CHyCH2), 75.35 (C-2), 100.78
(C-3), 115.69 (C-8), 117.71 (CH2CHyCH2), 120.64 (C-6)*,
121.69 (C-4a), 122.47 (C-5)*, 129.49 (C-7), 133.65
(CH2CHyCH2), 145.92 (C-4), 154.66 (C-8a). MS (70 eV);
m/z (%): 344 (1) [M1], 303 (100) [M1-C3H5], 259 (8), 173
(5), 157 (5) [C9H21Si1], 131 (6), 115 (37) [C6H15Si1], 102
(18), 87 (10), 73 (9) [C3H9Si1], 59 (10). Anal. calcd. for
C21H32O2Si (344.57): C, 73.20; H, 9.36. Found: C, 73.10; H,
9.49.
4
3
1.1.11. 6-Benzyloxycarbonyl-1-ethoxycarbonyl-2-(2-pro-
penyl)-4-tri-iso-propyl silyloxy-2H-quinoline (6i). Reac-
tion of 0.30 g (0.85 mmol) 4f with 0.30 ml (1.12 mmol)
TIPSOTf, 0.13 ml (1.12 mmol) 2,6-lutidine and 0.34 ml
(1.10 mmol) allyltri-n-butyltin according to the General
Procedure yielded after ¯ash chromatography on 95 g silica
gel (cyclohexane/diethyl etherˆ9:1) 0.42 g (90%) 6i as a
colourless oil. Rfˆ0.21 (cyclohexane/diethyl etherˆ9:1)
IR (CCl4): nˆ3068 cm21, 3034 (arom. CH, CyCH); 2945,
2881, 2867 (CH); 1719 (CyO); 1649 (CyC); 1492; 1463;
1385; 1351; 1304; 1243. UV (acetonitrile): lmax (log
1.1.13. 2-(2-Propenyl)-4-tri-iso-propyl silyloxy-2H-thio-
chromene (6k). Reaction of 0.30 g (1.85 mmol) 4h with
0.50 ml (1.86 mmol) TIPSOTf, 0.22 ml (1.89 mmol)
2,6-lutidine and 0.75 ml (2.42 mmol) allyltri-n-butyltin
according to the General Procedure yielded after ¯ash
chromatography on 95 g silica gel (cyclohexane/diethyl
etherˆ80:1) 0.61 g (91%) 6k as a yellow oil. Rfˆ0.43
(cyclohexane/diethyl etherˆ80:1). IR (CCl4): nˆ
3063 cm21, 3030 (arom. CH, CyCH); 2945, 2892, 2867
(CH); 1634 (CyC); 1468; 1346; 1259. UV (acetonitrile):
1
e)ˆ261 nm (4.61). H NMR (270 MHz, CDCl3): dˆ1.07
[d, 3Jˆ7.0 Hz, 18H, 3£CH(CH3)2], 1.16±1.33 [m, 6H,
3£CH(CH3)2, CH2CH3], 2.06±2.26 (m, 2H, CH2CHyCH2),
4.16±4.31 (m, 2H, CH2CH3), 4.85±5.00 (m, 2H,
CH2CHyCH2), 5.05 (q, 3Jˆ6.5 Hz, 1H, 2H), 5.19 (d,
3Jˆ6.5 Hz, 1H, 3H), 5.25±5.34 (m, 2H, CO2CH2C6H5),
5.70 (mc, 1H, CH2CHyCH2), 7.26±7.45 (m, 5H, 200H,
lmax (log e)ˆ225 nm (4.14), 255 (4.06), 325 (3.29). H
1
NMR (270 MHz, CDCl3): dˆ1.10 [d, 3Jˆ7.0 Hz, 18H,
3£CH(CH3)2], 1.18±1.32 [m, 3H, 3£CH(CH3)2], 2.39 (t,
3
3Jˆ6.5 Hz, 2H, CH2CHyCH2), 3.63 (q, Jˆ6.5 Hz, 1H,
2H), 5.00±5.10 (m, 2H, CH2CHyCH2), 5.19 (d, 3Jˆ
6.5 Hz, 1H, 3H), 5.78 (mc, 1H, CH2CHyCH2), 7.06±7.14
(m, 2H, 6H, 8H), 7.18±7.23 (m, 1H, 7H), 7.58±7.63 (m, 1H,
5H). 13C NMR (68 MHz, CDCl3): dˆ12.78 [3£CH(CH3)2],
18.07, 18.09 [3£CH(CH3)2], 38.51 (C-2), 40.79
(CH2CHyCH2), 104.26 (C-3), 117.47 (CH2CHyCH2),
124.14 (C-6), 125.09 (C-8), 127.13 (C-7), 128.12 (C-5),
131.63 (C-4a), 132.67 (C-8a), 134.71 (CH2CHyCH2),
149.06 (C-4). MS (70 eV); m/z (%): 360 (5) [M1], 319
(100) [M1-C3H5], 275 (6), 189 (5), 157 (4) [C9H21Si1],
115 (22) [C6H15Si1], 110 (24), 102 (17), 87 (10), 73 (11)
3
300H, 400H, 500H, 600H), 7.63 (d, Jˆ8.5 Hz, 1H, 8H), 7.94
4
3
4
(dd, Jˆ2.0 Hz, Jˆ8.5 Hz, 1H, 7H), 8.28 (d, Jˆ2.0 Hz,
1H, 5H). 13C NMR (68 MHz, CDCl3): dˆ12.64
[3£CH(CH3)2], 14.38 (CO2CH2CH3), 17.96, 17.99
[3£CH(CH3)2], 39.27 (CH2CHyCH2), 52.46 (C-2), 62.32
(CO2CH2CH3), 66.63 (CO2CH2C6H5), 105.06 (C-3),
117.81 (CH2CHyCH2), 123.81 (C-8), 124.21 (C-5),
125.16 (C-6), 126.20 (C-4a), 128.13 (C-400), 128.16 (C-300,
C-500)*, 128.52 (C-200, C-600)*, 129.36 (C-7), 133.59

U. Beifuss et al. / Tetrahedron 57 (2001) 1005±1013
1011
[C3H9Si1], 59 (13). Anal. calcd. for C21H32OSSi (360.63):
C, 69.94; H, 8.94. Found: C, 69.87; H 8.84.
50H), 8.57 (d, 3Jˆ14.5 Hz, 1H, yCH), 11.20 (dbr,
3Jˆ14.5 Hz, 1H, NH, D2O exchangeable). 13C NMR
(68 MHz, CDCl3): dˆ27.05 (2£CH3), 87.81 (C-2), 105.32
(C-5), 119.47 (C-20, C-60), 119.93 (C-40), 133.15 (C-30,
C-50), 136.89 (C-10), 152.28 (CH), 163.27 (CyO), 165.48
(CyO). MS (70 eV); m/z (%): 327 (38) [M1], 325 (40)
[M1], 312 (2) [M1-CH3], 310 (1) [M1-CH3], 269 (92)
[M1-C3H6O], 267 (88) [M1-C3H6O], 252 (10), 250 (12),
241 (6) [269-CO], 239 (7) [267-CO], 225 (58) [269-CO2],
224 (100), 223 (60) [267-CO2], 222 (99), 197 (75) [225-
CO], 195 (78) [223-CO], 182 (12), 173 (14), 171 (16),
169 (14), 157 (22) [C6H4Br1], 155 (20) [C6H4Br1], 144
(87), 116 (97), 89 (48), 76 (22), 63 (20), 53 (18).
1.1.14. (2SR,3SR)-1-Benzyloxycarbonyl-3-bromo-2-(2-
propenyl)-4-oxo-1,2,3,4-tetrahydroquinoline (9). 0.18 ml
(0.93 mmol) TMSOTf was added dropwise to 0.20 g (0.72
mmol) 4a and the mixture was held at room temperature for
1 h under argon. After the successive addition of 1.5 ml dry
dichloromethane, 0.11 ml (0.94 mmol) 2,6-lutidine and
0.29 ml (0.94 mmol) allyltri-n-butyltin at 08C the resulting
solution was stirred for 3 h at room temperature. The reac-
tion mixture was cooled to 2788C, treated with 0.14 g
(0.79 mmol) NBS, warmed to room temperature, poured
into 20 ml saturated potassium hydrogen carbonate solution
and extracted with dichloromethane (3£20 ml). The com-
bined organic phases were dried over sodium sulfate and the
solvent was removed at reduced pressure on a rotary
evaporator. Finally the crude product was puri®ed by ¯ash
chromatography on 95 g silica gel (cyclohexane/ethyl
acetateˆ6:1) to yield 138 mg (48%) 9 as a yellow oil.
Rfˆ0.27 (cyclohexane/ethyl acetateˆ6:1) IR (CCl4): nˆ
3080 cm21, 3035 (arom. CH, CyCH); 2979 (CH); 1721
(CyO, carbamate); 1693 (CyO); 1602 (CyC); 1481;
1461; 1388; 1335; 1300; 1238; 1225. UV (acetonitrile):
1.1.16.
2,2-Dimethyl-5-(4-benzyloxycarbonyl-phenyl-
amino-methylene)-[1.3]dioxan-4,6-dione (10b). A solu-
tion of 4.6 g (31.9 mmol) Meldrum0s acid (13) and 30 ml
(273.9 mmol) methyl orthoformate (14) was heated to re¯ux
for 2 h under argon. At room temperature 4.99 g
(22.0 mmol) benzyl 4-amino benzoate (12b) were added
and the reaction mixture was heated for another 6 h under
re¯ux. The precipitate was collected after cooling followed
by recrystallization from methanol to yield 7.56 g (90%)
10b as pale yellow crystals. Mp.: 194.5±1968C (methanol).
Rfˆ0.20 (toluene/ethyl acetateˆ9:1). IR (KBr): nˆ
3164 cm21 (NH); 3031, 3008 (arom. CH, CyCH); 2993
(CH); 1723, 1683 (CyO); 1634 (CyC); 1605; 1581; 1461;
1414; 1379; 1310; 1282. UV (acetonitrile): lmax (log
e)ˆ223 nm (4.19), 335 (4.59). 1H NMR (270 MHz,
CDCl3): dˆ1.74 (s, 6H, 2£CH3), 5.35 (s, 2H,
1
lmax (log e)ˆ237 nm (4.40), 268 (3.89), 346 (3.52). H
NMR (270 MHz, CDCl3): dˆ2.20±2.40 (m, 2H,
CH2CHyCH2), 4.39 (d, 3Jˆ2.0 Hz, 1H, 3H), 4.90 (dd,
2Jˆ1.5 Hz, 3Jˆ17.0 Hz, 1H, CH2CHyCHH(trans)), 5.04
2
3
(dd, Jˆ1.5 Hz, Jˆ10.0 Hz, 1H, CH2CHyCHH(cis)), 5.13
3
3
2
(dt, Jˆ2.0 Hz, Jˆ7.0 Hz, 1H, 2H), 5.27 (d, Jˆ12.5 Hz,
1H, CO2CHaHC6H5), 5.36 (d, 2Jˆ12.5 Hz, 1H,
CO2CH2C6H5), 7.27 (d, Jˆ9.0 Hz, 2H, 20H, 60H), 7.28±
3
3
3
3
3
CO2CHHbC6H5), 5.68 (tdd, Jˆ7.0 Hz, Jˆ10.0 Hz, Jˆ
17.0 Hz, 1H, CH2CHyCH2), 7.20 (dt, 4Jˆ1.0 Hz, 3Jˆ
8.0 Hz, 1H, 6H), 7.30±7.44 (m, 5H, 20H, 30H, 40H, 50H,
7.41 (m, 5H, CO2CH2C6H5), 8.13 (d, Jˆ9.0 Hz, 2H, 30H,
50H), 8.67 (d, 3Jˆ14.0 Hz, 1H, yCH), 11.29 (dbr,
3Jˆ14.0 Hz, 1H, NH, D2O exchangeable). 13C NMR
4
3
60H), 7.56 (dt, Jˆ1.5 Hz, Jˆ8.0 Hz, 1H, 7H), 7.81 (dbr,
(68 MHz,
CDCl3):
dˆ27.12
(2£CH3),
67.04
3Jˆ8.0 Hz, 1H, 8H), 8.04 (dd, Jˆ1.5 Hz, Jˆ8.0 Hz, 1H,
5H). 13C NMR (68 MHz, CDCl3): dˆ34.69 (CH2CHyCH2),
48.16 (C-3), 59.71 (C-2), 68.47 (CO2CH2C6H5), 119.30
(CH2CHyCH2), 121.59 (C-4a), 124.48, 124.59 (C-8, C-6),
128.14, 128.39, 128.55 (C-5, C-20, C-30, C-40, C-50, C-60),
132.05 (CH2CHyCH2), 135.17 (C-7), 135.48 (C-10), 140.02
(C-8a), 154.28 (CO2CH2C6H5), 186.13 (C-4). MS (70 eV);
m/z (%): 401 (1) [M1], 399 (1) [M1], 360 (5) [M1-C3H5],
358 (5) [M1-C3H5], 316 (5) [360-CO2], 314 (5) [358-CO2],
226 (30), 224 (29), 145 (10), 91 (100) [C7H17 ], 84 (40).
Anal. calcd. for C20H18BrNO3 (400.27): C, 60.01; H, 4.53.
Found: C, 60.23; H, 4.73.
(CO2CH2C6H5), 88.65 (C-2), 105.48 (C-5), 117.33 (C-20,
C-60), 128.18 (C-40), 128.33 (C-300, C-500)*, 128.43 (C-400),
128.65 (C-200, C-600)*, 131.89 (C-30, C-50), 135.69 (C-100),
141.38 (C-10), 151.94 (CH), 163.17 (CyO), 165.20, 165.39
(CO2CH2C6H5, CyO). MS (70 eV); m/z (%): 381 (18) [M1],
323 (86) [M1 C3H6O], 278 (53), 172 (21), 144 (100), 91 (86)
[C7H17 ], 65 (5) [C5H51]. Anal. calcd. for C21H19NO6
(381.38): C, 66.14; H, 5.02. Found: C, 66.31; H, 4.91.
4
3
1.1.17. 6-Bromo-4-oxo-4H-quinoline (11a). 5.75 g (17.6
mmol) 10a were dissolved in 91 ml hot diphenyl ether and
re¯uxed until the formation of gaseous products ceased. The
product was precipitated by cooling and subsequent mixing
with 91 ml pentane. After 48 h at room temperature the
precipitate was isolated by ®ltration followed by washing
with 68 ml pentane and drying under vacuum (1.33£1023
mbar). Puri®cation of the crude product by sublimation
(2008C, 1.33£1023 mbar) delivered 2.82 g (72%) 11a as a
colourless solid. Mp.: 286±2918C. Rfˆ0.47 (ethyl acetate/
ethanolˆ7:3). IR (KBr): nˆ3300±2500 cm21 (NH); 3061
(arom. CH, CyCH); 1625 (CyO); 1603 (CyC); 1552; 1510;
1465; 1346; 1304; 1198. UV (acetonitrile): lmax (log
e)ˆ212 nm (4.33), 236 (4.03), 292 (3.52), 326 (3.72), 339
(3.74). 1H NMR (270 MHz, CD3OD / [D6] DMSO): dˆ6.32
1.1.15. 2,2-Dimethyl-5-(4-bromo-phenylamino-methyl-
ene)-[1.3]dioxan-4,6-dione (10a). A solution of 4.6 g
(31.9 mmol) Meldrum0s acid (13) and 60 ml (547.9 mmol)
methyl orthoformate (14) was heated to re¯ux for 2 h under
argon. At room temperature 3.8 g (22.1 mmol) 4-bromoani-
line (12a) were added and the reaction mixture was heated
for another 6 h under re¯ux. The precipitate was collected
after cooling followed by recrystallization from methanol to
yield 6.11 g (85%) 10a as yellow crystals. Mp.: 208±2098C
(methanol). Rfˆ0.42 (cyclohexane/ethyl acetateˆ2:1). IR
(KBr): nˆ3258 cm21 (NH); 3100 (arom. CH, CyCH);
2993, 2925 (CH); 1719, 1674 (CyO); 1627 (CyC); 1578;
1483; 1407; 1391; 1337; 1289; 1269; 1204. 1H NMR
(270 MHz, CDCl3): dˆ1.74 (s, 6H, 2£CH3), 7.11 (d,
3
3
(d, Jˆ7.5 Hz, 1H, 3H), 7.52 (d, Jˆ9.0 Hz, 1H, 8H), 7.80
4
3
3
(dd, Jˆ2.5 Hz, Jˆ9.0 Hz, 1H, 7H), 7.98 (d, Jˆ7.5 Hz,
1H, 2H), 8.35 (d, 4Jˆ2.5 Hz, 1H, 5H). 13C NMR
(68 MHz, CD3OD / [D6] DMSO): dˆ110.23 (C-3), 118.47
3
3Jˆ9.0 Hz, 2H, 20H, 60H), 7.54 (d, Jˆ9.0 Hz, 2H, 30H,

1012
U. Beifuss et al. / Tetrahedron 57 (2001) 1005±1013
(C-6), 121.75 (C-8), 128.11 (C-4a), 128.69 (C-5), 136.43
(C-7), 140.30 (C-8a), 141.74 (C-2), 179.26 (C-4). MS
(70 eV); m/z (%): 225 (99) [M1], 223 (100) [M1], 197
(17) [M1-CO], 195 (18) [M1-CO], 169 (8), 144 (12) [M1-
Br], 116 (37), 89 (17). Anal. calcd. for C9H6BrNO (224.06):
C, 48.25; H, 2.70. Found: C, 48.10; H, 2.82.
(2) [M1], 357 (2) [M1], 315 (1) [M1-CO2], 313 (3) [M1-
CO2], 150 (3), 147 (9), 119 (3), 116 (3), 91 (100) [C7H17 ], 65
(5) [C5H15 ]. Anal. calcd. for C17H12BrNO3 (358.19): C,
57.01; H, 3.38. Found: C, 56.74; H, 3.60.
1.1.20. 6-Bromo-1-ethoxycarbonyl-4-oxo-4H-quinoline
(4d). 1.00 g (4.5 mmol) 11a was added to a suspension of
0.28 g (11.7 mmol) sodium hydride in 20 ml dry THF under
argon. At 508C 1.25 g (11.5 mmol) ethyl chloroformate was
added dropwise and the reaction mixture was stirred for 48 h
at room temperature. After quenching with 7.1 ml water the
mixture was neutralized with 2N hydrochloric acid and
extracted with dichloromethane (3£20 ml). The combined
organic phases were dried over sodium sulfate and the
solvent was removed at reduced pressure on a rotary
evaporator. Finally the crude product was puri®ed by ¯ash
chromatography on 95 g silica gel (cyclohexane/ethyl
acetateˆ1.9:1) to yield 0.96 g (73%) 4d as a colourless
solid. Mp.: 104±1058C. Rfˆ0.18 (cyclohexane/ethyl acetateˆ
2:1). IR (CCl4): nˆ3130 cm21 (arom. CH, CyCH); 2985
(CH); 1758 (CyO, carbamate); 1659 (CyO); 1621 (CyC);
1594; 1468; 1444; 1370; 1345; 1270; 1216. UV (aceto-
nitrile): lmax (log e)ˆ216 nm (4.17), 240 (4.37), 328
(4.06). 1H NMR (270 MHz, CDCl3): dˆ1.47 (t, 3Jˆ
7.0 Hz, 3H, CO2CH2CH3), 4.52 (q, 3Jˆ7.0 Hz, 2H,
CO2CH2CH3), 6.28 (d, 3Jˆ8.5 Hz, 1H, 3H), 7.74 (dd,
1.1.18. 6-Benzyloxycarbonyl-4-oxo-4H-quinoline (11b).
4.68 g (12.3 mmol) 10b were dissolved in 74 ml hot
diphenyl ether and re¯uxed until the formation of gaseous
products ceased. The product was precipitated by cooling
and subsequent mixing with 74 ml pentane. After 18 h at
room temperature the precipitate was isolated by ®ltration
followed by washing with 150 ml pentane and drying under
vacuum (1.33£1023 mbar). Flash chromatography of the
crude product on 95 g silica gel (ethyl acetate/ethanolˆ
4:1) gave 2.53 g (74%) 11b as a pale yellow solid. Mp.:
244±2478C. Rfˆ0.44 (ethyl acetate/ethanolˆ4:1). IR
(KBr): nˆ3300±2700 cm21 (NZH); 3061 (arom. CH,
CyCH); 2970, 2885, 2835 (CH); 1717 (CyO, ester); 1635
(CyO); 1559; 1498; 1280; 1246. UV (acetonitrile): lmax
(log e)ˆ221 nm (3.97), 250 (3.47), 258 (3.47), 305 (3.20),
1
325 (3.31), 335 (3.33). H NMR (270 MHz, CD3OD/[D6]
DMSO): dˆ5.44 (s, 2H, CO2CH2C6H5), 6.33 (d, 3Jˆ7.5 Hz,
3
1H, 3H), 7.38±7.55 (m, 5H, CO2CH2C6H5), 7.68 (d, Jˆ
3
9.0 Hz, 1H, 8H), 8.02 (d, Jˆ7.5 Hz, 1H, 2H), 8.30 (dd,
3
4
3
3
4Jˆ2.0 Hz, Jˆ9.0 Hz, 1H, 7H), 8.94 (d, Jˆ2.0 Hz, 1H,
5H). 13C NMR (68 MHz, CD3OD/[D6] DMSO): dˆ67.96
(CO2CH2C6H5), 111.08 (C-3), 120.16 (C-8), 126.18 (C-6)*,
126.61 (C-4a)*, 129.10 (C-40), 129.45 (C-5, C-30, C-50)*,
129.79 (C-20, C-60)*, 133.27 (C-7), 137.63 (C-10), 142.03
(C-2), 144.28 (C-8a), 166.81 (CO2CH2C6H5), 180.19 (C-4).
MS (70 eV); m/z (%): 279 (26) [M1], 172 (100) [M1-
C7H7O], 145 (18), 116 (10), 91 (64) [C7H17 ], 65 (7) [C5H51].
4Jˆ2.5 Hz, Jˆ9.5 Hz, 1H, 7H), 8.37 (d, Jˆ8.5 Hz, 1H,
4
3
2H), 8.48 (d, Jˆ2.5 Hz, 1H, 5H), 8.58 (d, Jˆ9.5 Hz, 1H,
8H). 13C NMR (68 MHz, CDCl3): dˆ14.16 (CO2CH2CH3),
65.36 (CO2CH2CH3), 112.47 (C-3), 119.44 (C-6), 122.03
(C-8), 127.99 (C-4a), 129.13 (C-5), 135.71 (C-7), 137.28
(C-8a), 138.46 (C-2), 151.10 (CO2CH2CH3), 177.56 (C-4).
MS (70 eV); m/z (%): 297 (97) [M1], 295 (96) [M1], 253
(5), 251 (5), 238 (20), 236 (19), 225 (70), 223 (100), 197
(10), 196 (10), 195 (10), 194 (10), 172 (5), 170 (5), 147 (5),
144 (19), 116 (21), 115 (23), 89 (10), 88 (10), 29 (97)
[C2H15 ]. Anal. calcd. for C12H10BrNO3 (296.12): C, 48.67;
H, 3.40. Found: C, 48.97; H, 3.56.
1.1.19. 1-Benzyloxycarbonyl-6-bromo-4-oxo-4H-quino-
line (4c). 1.00 g (4.5 mmol) 11a was added to a suspension
of 0.30 g (12.5 mmol) sodium hydride in 20 ml dry THF
under argon. At 608C 1.15 g (6.7 mmol) benzyl chloro-
formate was added dropwise and the reaction mixture was
stirred for 24 h at room temperature. After quenching with
13 ml water the mixture was neutralized with 2N hydro-
chloric acid and extracted with dichloromethane (3£
15 ml). The combined organic phases were dried over
sodium sulfate and the solvent was removed at reduced
pressure on a rotary evaporator. Finally the crude product
was puri®ed by crystallization from cyclohexane/ethyl
acetateˆ1:2 to yield 1.23 g (77%) 4c as pale yellow crystals.
Mp.: 134±1378C (cyclohexane/ethyl acetateˆ1:2). Rfˆ0.27
(cyclohexane/ethyl acetateˆ2:1). IR (KBr): nˆ3067 cm21
(arom. CH, CyCH); 2985 (CH); 1754 (CyO, carbamate);
1644 (CyO); 1592; 1468; 1373; 1350; 1266; 1211. UV
1.1.21. 1,6-Dibenzyloxycarbonyl-4-oxo-4H-quinoline (4e).
20.00 g (71.6 mmol) 11b was added to a suspension of 2.23 g
(93.1 mmol) sodium hydride in 143 ml dry THF and the
mixture was re¯uxed for 1 h under argon. 15.8 g
(93.1 mmol) benzyl chloroformate was added dropwise and
the reaction mixture was stirred for 1 h at room temperature.
After quenching with 72 ml water the mixture was extracted
with dichloromethane (3£70 ml). The combined organic
phases were dried over sodium sulfate and the solvent was
removed at reduced pressure on a rotary evaporator. Finally
the crude product was puri®ed by ¯ash chromatography on
500 g silica gel (diethyl ether/light petroleumˆ1:1) to give
26.6 g (90%) 4e as a colourless solid. Mp.: 110±1118C.
Rfˆ0.20 (cyclohexane/ethyl acetateˆ2:1). IR (KBr):
nˆ3052 cm21, 3030 (arom. CH, CyCH); 2952 (CH); 1760
(CyO, carbamate); 1715 (CyO, ester); 1649 (CyO); 1610
(CyC); 1456; 1353; 1266; 1213. UV (acetonitrile): lmax
(log e)ˆ210 nm (4.46), 253 (4.41), 260 (4.44), 287 (3.40),
307 (4.05), 319 (4.12). 1H NMR (270 MHz, CDCl3): dˆ5.38
(s, 2H, CO2CH2C6H5), 5.46 (s, 2H, NCO2CH2C6H5), 6.27 (d,
3Jˆ9.0 Hz, 1H, 3H), 7.32±7.46 (m, 10H, 20H, 30H, 40H, 50H,
60H, 200H, 300H, 400H, 500H, 600H), 8.30 (dd, 4Jˆ2.5 Hz,
1
(acetonitrile): lmax (log e)ˆ240 nm (4.40), 328 (4.10). H
NMR (270 MHz, CDCl3): dˆ5.45 (s, 2H, CO2CH2C6H5),
3
6.25 (d, Jˆ8.5 Hz, 1H, 3H), 7.40±7.44 (m, 5H, 20H, 30H,
4
3
40H, 50H, 60H), 7.72 (dd, Jˆ2.5 Hz, Jˆ9.5 Hz, 1H, 7H),
3
4
8.35 (d, Jˆ8.5 Hz, 1H, 2H), 8.47 (d, Jˆ2.5 Hz, 1H, 5H),
8.59 (d, Jˆ9.5 Hz, 1H, 8H). 13C NMR (68 MHz, CDCl3):
3
dˆ70.76 (CO2CH2C6H5), 112.60 (C-3), 119.51 (C-6),
122.03 (C-8), 127.96 (C-4a), 128.91 (C-30, C-50)*, 128.98
(C-20, C-60)*, 129.11, 129.37 (C-40, C-5), 133.67 (C-10),
135.72 (C-7), 137.21 (C-8a), 138.34 (C-2), 150.97
(CO2CH2C6H5), 177.47 (C-4). MS (70 eV); m/z (%): 359
3
3Jˆ9.0 Hz, 1H, 7H), 8.35 (d, Jˆ9.0 Hz, 1H, 2H), 8.72 (d,
3Jˆ9.0 Hz, 1H, 8H), 9.02 (d, 4Jˆ2.5 Hz, 1H, 5H). 13C NMR

U. Beifuss et al. / Tetrahedron 57 (2001) 1005±1013
1013
Org. React. 1989, 37, 57±575. (c) Fleming, I. In Comprehen-
sive Organic Synthesis, Trost, B. M., Fleming, I., Eds.; Perga-
mon Press: Oxford, 1991; Vol. 2, pp 563±593.
(68 MHz, CDCl3): dˆ67.09 (CO2CH2C6H5), 70.89
(NCO2CH2C6H5), 113.13 (C-3), 120.33 (C-8), 126.30 (C-6),
127.20 (C-4a), 128.37 (C-5), 128.42 (C-300, C-500)*, 128.63
(C-200, C-600)*, 128.75 (C-400)*, 128.96 (C-30, C-50)*, 129.02
(C-20, C-60)*, 129.44 (C-40)*, 133.41 (C-7), 133.65 (C-10),
135.71 (C-100), 138.47 (C-2), 141.31 (C-8a), 151.07
(NCO2CH2C6H5), 165.26 (CO2CH2C6H5), 178.27 (C-4).
MS (70 eV); m/z (%): 413 (5) [M1], 369 (60), 262 (5), 172
(4), 91 (100) [C7H17 ], 65 (7) [C5H15 ], 44 (44). HRMS calcd.
for C25H19NO5: 413.1263. Found: 413.1263.
È
2. Konig, K.; Neumann, W. P. Tetrahedron Lett. 1967, 6, 495±
498.
3. Perlmutter, P. Conjugate Addition Reactions in Organic
Synthesis; Pergamon Press: Oxford, 1992.
4. Sato, M.; Aoyagi, S.; Yago, S.; Kibayashi, C. Tetrahedron
Lett. 1996, 37, 9063±9066.
Â
5. Brocherieux-Lanoy, S.; Dhimane, H.; Vanucci-Bacque, C.;
Lhommet, G. Synlett 1999, 405±408.
1.1.22. 6-Benzyloxycarbonyl-1-ethoxycarbonyl-4-oxo-4H-
quinoline (4f). 3.00 g (10.7 mmol) 11b was added to a
suspension of 0.33 g (13.9 mmol) sodium hydride in 21 ml
dry THF and the mixture was re¯uxed for 1 h under argon.
1.51 g (13.9 mmol) ethyl chloroformate was added dropwise
and the reaction mixture was stirred for 2 h at room tempera-
ture. After quenching with 11 ml water the mixture was
extracted with dichloromethane (3£10 ml). The combined
organic phases were dried over sodium sulfate and the solvent
was removed at reduced pressure on a rotary evaporator.
Finally the crude product was puri®ed by ¯ash chromato-
graphy on silica gel (ethyl acetate/light petroleumˆ2:1) to
yield 3.52 g (94%) 4f as a colourless solid. Mp.: 132±
1348C. Rfˆ0.13 (cyclohexane/ethyl acetateˆ2:1). IR (KBr):
nˆ3116 cm21, 3059 (arom. CH, CyCH); 2999 (CH); 1744
(CyO, carbamate); 1721 (CyO, ester); 1657 (CyO); 1610
(CyC); 1480; 1448; 1387; 1365; 1332; 1294; 1282; 1223.
UV (acetonitrile): lmax (log e)ˆ224 nm (4.40), 252 (4.37),
6. (a) Itoh, T.; Miyazaki, M.; Nagata, K.; Hasegawa, H.;
Ohsawa, A.; Nakamura, K. T. Heterocycles 1998, 47, 125±
128. (b) Yamaguchi, R.; Hatano, B.; Nakayasu, T.; Kozima, S.
Tetrahedron Lett. 1997, 38, 403±406. (c) Itoh, T.;
Hasegawa, H.; Nagata, K.; Matsuya, Y.; Okada, M.;
Ohsawa, A. Chem. Pharm. Bull. 1994, 42, 1768±1773.
(d) Itoh, T.; Hasegawa, H.; Nagata, K.; Ohsawa, A. J. Org.
Chem. 1994, 59, 1319±1325. (e) Yamaguchi, R.;
Mochizuki, K.; Kozima, S.; Takaya, H. J. Chem. Soc.,
Â
Chem. Commun. 1993, 981±982. (f) Magnus, P.; Rodrõguez-
Â
Lopez, J.; Mulholland, K.; Matthews, I. J. Am. Chem. Soc.
1992, 114, 382±383. (g) Yamaguchi, R.; Moriyasu, M.;
Yoshioka, M.; Kawanisi, M. J. Org. Chem. 1988, 53, 3507±
3512. (h) Yamaguchi, R.; Moriyasu, M.; Yoshioka, M.;
Kawanisi, M. J. Org. Chem. 1985, 50, 287±288.
7. (a) Beifuss, U.; Taraschewski, M. J. Chem. Soc, Perkin Trans.
1 1997, 2807±2809. (b) Beifuss, U.; Ledderhose, S. Synlett
1997, 313±315. (c) Beifuss, U.; Ledderhose, S. Synlett 1995,
938±940. (d) Beifuss, U.; Ledderhose, S. In Organosilicon
Chemistry II: From Molecules to Materials, Auner, N.,
Weis, J., Eds.; VCH: Weinheim, 1996; pp 225±230.
8. (a) Beifuss, U.; Tietze, M.; Gehm, H. Synlett 1996, 182±184.
(b) Beifuss, U.; Gehm, H.; Tietze, M. In Organosilicon
Chemistry II: From Molecules to Materials, Auner, N.,
Weis, J., Eds.; VCH: Weinheim, 1996; pp 219±224.
(c) Beifuss, U.; Gehm, H.; Noltemeyer, M.; Schmidt, H.-G.
Angew. Chem. 1995, 107, 705±707; Angew. Chem., Int. Ed.
Engl. 1995, 34, 647±649. (d) Beifuss, U.; Gehm, H.
Phosphorus, Sulfur and Silicon 1994, 95&96, 339±340.
9. Simchen, G. In Advances in Silicon Chemistry, Larson, G. L.,
Ed.; JAI Press: Greenwich, 1991; Vol. 1, pp 189±301.
10. Hagen, G.; Mayr, H. J. Am. Chem. Soc. 1991, 113, 4954±
4961.
1
260 (4.40), 287 (3.98), 308 (4.03), 320 (4.09). H NMR
(270 MHz, CDCl3): dˆ1.48 (t, 3Jˆ7.0 Hz, 3H,
3
CO2CH2CH3), 4.54 (q, Jˆ7.0 Hz, 2H, CO2CH2CH3), 5.39
3
(s, 2H, CO2CH2C6H5), 6.30 (d, Jˆ8.5 Hz, 1H, 3H), 7.35±
4
7.46 (m, 5H, 200H, 300H, 400H, 500H, 600H), 8.31 (dd, Jˆ
3
3
2.0 Hz, Jˆ9.0 Hz, 1H, 7H), 8.37 (d, Jˆ8.5 Hz, 1H, 2H),
3
4
8.71 (d, Jˆ9.0 Hz, 1H, 8H), 9.03 (d, Jˆ2.0 Hz, 1H, 5H).
13C NMR (68 MHz, CDCl3): dˆ14.16 (CO2CH2CH3), 65.48
(CO2CH2CH3), 67.08 (CO2CH2C6H5), 112.96 (C-3), 120.31
(C-8), 126.29 (C-6), 127.10 (C-4a), 128.37 (C-5), 128.41
(C-300, C-500)*, 128.63 (C-200, C-600)*, 128.76 (C-400), 133.36
(C-7), 135.71 (C-100), 138.60 (C-2), 141.33 (C-8a), 151.16
(CO2CH2CH3), 165.28 (CO2CH2C6H5), 178.34 (C-4). MS
(70 eV); m/z (%): 351 (20) [M1], 244 (44) [M1-C7H7O],
234 (5), 217 (12), 200 (12), 172 (22), 144 (5), 116 (5), 91
(100) [C7H17 ], 65 (5) [C5H51]. Anal. calcd. for C20H17NO5
(351.36): C, 68.37; H, 4.88. Found: C, 68.43; H, 5.04.
11. Witherup, K. M.; Ransom, R. W.; Graham, A. C.;
Bernard, A. M.; Salvatore, M. J.; Lumma, W. C.;
Anderson, P. S.; Pitzenberger, S. M.; Varga, S. L. J. Am.
Chem. Soc. 1995, 117, 6682±6685.
Â
12. Beifuss, U.; Feder, G.; Bes, T.; Uson, I. Synlett 1998, 649±
651.
Acknowledgements
Financial support from the Fonds der Chemischen Industrie,
Frankfurt am Main, is gratefully acknowledged.
13. Kocienski, P. J. Protecting Groups; Thieme: Stuttgart, 1994.
14. Cassis, R.; Tapia, R.; Valderrama, J. A. Synthetic Commun.
1985, 15, 125±133.
References
1. (a) Yamamoto, Y.; Asao, N. Chem. Rev. 1993, 93, 2207±
Á
2293. (b) Fleming, I.; Dunogues, J.; Smithers, R.