Palladium catalysed queuing processes. Part 2: Termolecular cyclization-anion capture employing carbon monoxide as a relay switch with in situ generated vinylstannanes

Article abstract of DOI:10.1016/S0040-4020(00)01104-2

The palladium catalysed termolecular queuing processes involving aryl iodides, carbon monoxide (1 atm) and in situ generated vinylstannanes as terminating agents afford a variety of complex heterocyclic α,β-unsaturated ketones in good yield.

Full text of DOI:10.1016/S0040-4020(00)01104-2

TETRAHEDRON
Pergamon
Tetrahedron 57 (2001) 1361±1367
Palladium catalysed queuing processes. Part 2:
Termolecular cyclization±anion capture employing carbon monoxide
as a relay switch with in situ generated vinylstannanes
p
Usman Anwar, Adele Casaschi, Ronald Grigg and Jose M. Sansano
Â
Molecular Innovation, Diversity and Automated Synthesis (MIDAS) Centre, Leeds University, Leeds LS2 9JT, UK
Received 29 August 2000; revised 10 November 2000; accepted 16 November 2000
AbstractÐThe palladium catalysed termolecular queuing processes involving aryl iodides, carbon monoxide (1 atm) and in situ generated
vinylstannanes as terminating agents afford a variety of complex heterocyclic a,b-unsaturated ketones in good yield. q 2001 Elsevier
Science Ltd. All rights reserved.
In the preceding paper1 we outlined the general concept of
relay switch reactants and their impact on our general
palladium catalysed cascade cyclization±anion capture
methodology.2 The new relay switch strategy has enabled
a wide variety of ter-, tetra-, penta-, hexa- and octamolecu-
lar queuing cascades to be developed1±3 with CO and allene
proving exceptionally versatile relay switch components.
hydrates, nucleosides, purines, benzodiazepinones,
b-lactams, a-amino esters, nitrogen heterocycles and
b-aryl/heteroaryl ethylamines.
The methodology outlined in Scheme 1 allows a highly
regioselective, temperature controlled cascade to occur,
which furnishes enones 4 in good yield (Table 1). We
have previously reported ter-, tetra- and pentamolecular
queuing cascades in which enones,4 a,b-unsaturated esters
and a,b-unsaturated amides5 are generated by processes
involving the combination of two relay switch reactants
(allene and CO). The enone functionality in 4 provides
considerable opportunities for further extended cascades
by combination with Michael additions, as 2p or 4p
In this paper we report examples of cascade processes
involving iodoarenes, CO (1 atm) and in situ generated
vinylstannanes (Scheme 1). We have previously demon-
strated the versatility of in situ generated vinylstannanes
in palladium catalysed cascade reactions3 and have provided
examples involving vinylstannanes derived from carbo-
Scheme 1.
Keywords: cascade reactions; palladium catalysis; hydrostannylation; Stille coupling; carbonylation; cyclization; termolecular queuing process.
p Corresponding author. Tel.: 144-113-233-6501; fax: 144-113-233-6501; e-mail: r.grigg@chem.leeds.ac.uk
0040±4020/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)01104-2

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U. Anwar et al. / Tetrahedron 57 (2001) 1361±1367
Table 1. Cascade hydrostannylation±cyclization±carbonylation±anion capture for synthesis of 4
Aryl iodide
Alkyne
HSnBu3(eq):1(eq)
3a:3ba
Time (h)
6
Product
Yield (%)b
65
1c
2a
1:2
90:10
1b
2b
1:1
90:10
16
61c
1c
1c
2b
1:1
1:1
90:10
90:10
16
18
60c
2c
60c
1d
1c
2c
1:1
1:1
90:10
85:15
18
18
58c
2d
63
Aryl iodide
Alkyne
HSnBu3(eq):4(eq)
3a:3ba
Time (h)
1
Product
Yield (%)b
53
1d
2e
1:1
85:15
1d
1d
2f
1:1
1:1
85:15
85:15
39
39
53
45
2g

U. Anwar et al. / Tetrahedron 57 (2001) 1361±1367
1363
Table 1. (continued)
Aryl iodide
Alkyne
HSnBu3(eq):1(eq)
3a:3ba
Time (h)
1
Product
Yield (%)b
1a
2h
1:1
90:10
58
1d
2h
1:1
90:10
1
63
1c
2i
1:1
85:15
16
56d
a Calculated by 1H NMR.
b Isolated yields after puri®cation by column chromatography (SiO2).
c Obtained as a 1:1 mixture of diastereomers.
d Reaction run in absence of carbon monoxide.
components in Diels±Alder reactions, as dipolarophiles in
1,3-dipolar cycloaddition reactions, and in cyclocondensa-
tion (e.g. Michael±imine formation) reactions. All these
processes have been achieved as part of related work on
cascades generating 3-methylene-chroman-4-ones and
quinolin-4-ones.6
it afforded a complex mixture of products due, presumably,
to the sensitivity of the expected 2-methylene-1,3-dicarbonyl
product 5 to the reaction conditions. However, product 4l
was obtained in good yield when the same reaction was run
in the absence of CO. The products arising from alkynes 2b
and 2c were 1:1 mixtures of diastereoisomers (1H NMR). A
similar ratio was observed in the early stages of the reaction
even at lower temperatures.
The ®rst step in Scheme 1 involves generation of the vinyl-
stannane 3 from the appropriate alkyne 2 (Chart 1). We
selected a range of acyclic 2a±d and cyclic 2e±h N-pro-
pargyl substrates together with acetylenic ketone 2i. The
palladium catalysed hydrostannylation7 of 2a±i occurred
smoothly in toluene at 08C over 1 h using Bu3SnH and a
catalytic system comprising 5 mol% Pd2dba3 and 20 mol%
tri(2-furyl)phosphine.3,8 A small aliquot of the reaction
The very fast reaction observed for the organostannane
derived from 3,7-dimethylxanthine is ascribed to a rapid
transmetallation step caused by co-ordination between tin
and the amide oxygen atom. This chair-like intermediate 6
is also favoured by the highly conjugated mesoionic form
containing the endocyclic double bond.
1
mixture was removed for H NMR analysis of the vinyl-
stannane regioisomeric ratio. The ratio of 3a:3b varied from
85:15 to 90:10 (Table 1) and this selectivity was judged
adequate for the proposed cascades. At this point 1a±d
were added and a CO ®lled balloon attached to the con-
denser. Raising the temperature to 90±1008C then initiated
the cascade as outlined in Scheme 1 affording enones 4a±k
(Table 1) in a well-ordered queuing process.
When 1c was reacted with alkyne 2i under these conditions

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U. Anwar et al. / Tetrahedron 57 (2001) 1361±1367
Chart 1.
Scheme 2.
Once again, the coupling reaction of the corresponding
b-vinylstannanes 3b furnished small amounts of products
7, which were discarded during puri®cation of the desired
major compounds 4. Regioisomeric E-enone 9 was
prepared, as a unique isomer in good yield (60%), employ-
ing different methodology for the generation of organo-
stannane 57b,9 using a lithium cuprate10 at 2788C (Scheme
2). E-Vinylstannane 8 was isolated after quenching the reac-
tion at 2788C with water. The coupling process was
completed in 6 h at 908C under a CO atmosphere employing
1c as starter affording 9 in 60% yield (Scheme 2). This latter
process illustrates the utility of N-propargyl substrates, such
as 2a±h, since 9 and its analogues provide additional oppor-
tunities for extended cascades as noted previously for 4.
recorded on Bruker QE300 and AM 400 machines operating
at 300 and 400 MHz, respectively. Unless otherwise
speci®ed, deuterochloroform was used as solvent with tetra-
methylsilane as internal standard. Microanalyses were
obtained using a Carlo Erba MOD 11016 instrument. Thin
layer chromatography was carried out on Whatman PESIL
G/UV polyester plates coated with a 0.2 mm layer of silica-
gel 60 (Merck 9385). Column chromatography was
performed with silica-gel 60 (Merck 9385). Petroleum
ether refers to the fraction with bp 40±608C. Anhydrous
DMF was commercially available (Aldrich), THF and
toluene were sodium dried under a nitrogen atmosphere
and n-hexane was distilled prior to use. Compounds 2a,
2b, 2g and 2h have been previously prepared by us3 and
2f and 2i are commercially available (ACROS).
In conclusion, the above discussion demonstrates that a
wide range of N-containing enones can be accessed through
a simple one pot protocol proceeding via palladium
catalysed hydrostannylation followed by cyclization±
carbonylation±anion capture, or through a sequential
process using a non-palladium catalysed hydrostannylation
reaction of a wide variety of alkynes. The unsaturated
ketones offer many synthetic possibilities due to their high
reactivity which permit the development of new extended
cascade processes.
1.1. Synthesis of propargyl derivatives 2c, 2d and 2e
1.1.1. N-Phenylsulphonyl-N-propargylleucine methyl
ester, 2c. Benzensulphonyl chloride (1.8 g, 10 mmol) was
added to a solution of (^)-leucine methyl ester hydro-
chloride (1.81 g, 10 mmol) and triethylamine (3.5 ml,
25 mmol) in dry dichloromethane (50 ml) cooled at 08C
and the mixture was stirred for 16 h at room temperature.
Water was added and the organic layer was separated, dried
(MgSO4), ®ltered and evaporated in vacuo to yield a pale
yellow solid. Sodium hydride (95% powder, 177 mg,
7 mmol) was slowly added to a solution of sulphonylated
amino ester (2.5 g, 7 mmol) in dry DMF (10 ml). After 2 h
at room temperature, propargyl bromide (80% in toluene,
2 g, 14 mmol) was added and stirring was continued for a
further 2 h at the same temperature. The mixture was diluted
with Et2O (30 ml) and water (50 ml) was added. The organic
1. Experimental
Melting points were determined on a Kof¯er hot-stage
apparatus and are uncorrected. Mass spectral data were
obtained from a VG Autospec mass spectrometer operating
at 70 eV. Nuclear magnetic resonance spectra were

U. Anwar et al. / Tetrahedron 57 (2001) 1361±1367
1365
layer was separated, dried (MgSO4), ®ltered and evaporated
in vacuo yielding a thick pale yellow oil, which was puri®ed
by column chromatography eluting with 1:1 v/v n-hexane±
ethyl acetate affording the product (1.8 g, 76%) as a thick
yellow oil. (Found: C, 59.2; H, 6.5; N, 4.05; S, 9.7.
C16H21NO4S requires: C, 59.4; H, 6.55, N, 4.3; S, 9.9%);
d 0.89, 0.91 (2d, Jˆ6.5 Hz, 6H, (CH3)2C), 1.55±1.85 (m,
3H, CH2CH), 2.22 (t, Jˆ2.5 Hz, 1H, CHxC), 3.51 (s, 3H,
CH3O), 4.13, 4.31 (2£dd, Jˆ19.0 and 2.5 Hz, 2H, CH2N),
4.59 (dd, Jˆ10.0 and 4.8 Hz, 1H, CHN) and 7.43±7.90 (m,
5H, ArH); m/z (%) 323 (M1, 8), 266 (25), 265 (45), 264
(100), 208 (17), 182 (43), 141 (35), 125 (18), 122 (20), 80
(15) and 77 (30).
potassium ¯uoride (10 ml) was added and stirring continued
for an additional hour. The suspension was ®ltered and ethyl
acetate added (20 ml). The organic phase was separated,
washed with water (10 ml), dried (Na2SO4) and concen-
trated under vacuo. The residue was puri®ed by ¯ash chro-
matography (SiO2) eluting with mixtures of petroleum
ether±ether. Yields and reaction times are given in Table 1.
1.2.1. Methyl 2-{2-[2-(3-methyl-1-phenylsulphonyl-2,3-
dihydro-1H-3-indolyl)acetyl]allyl(phenyl)sulphona-
mido}acetate, 4a. Viscous pale yellow oil. (Found: C, 59.5;
H, 5.2; N, 4.55; S, 11.0. C29H30N2O7S2 requires: C, 59.75;
H, 5.2; N, 4.8; S, 11.0%); d 1.13 (2£s, 3H, CH3C), 2.56,
3.03 (2£d, Jˆ17.3 Hz, 2H, CCH2CO), 3.57 (s, 3H, CH3O),
3.75, 3.93 (2£d, Jˆ11.0 Hz, 2H, CH2NAr), 4.02, 4.07 (2£s,
4H, CH2NCH2CO), 5.96, 6.03 (2£s, 2H, CH2yC) and 7.01±
7.83 (m, 14H, ArH); m/z (%) 582 (M1, 9), 272 (45), 271
(100), 170 (28), 144 (22), 141 (37), 131 (20), 130 (60), 77
(71) and 51 (16).
1.1.2. N-Acetyl-N-propargylbenzylamine, 2d. Sodium
hydride (95% powder, 252 mg, 10 mmol) was slowly
added to a solution of N-acetylbenzylamine (1.5 g,
10 mmol) in dry DMF (10 ml). After 2 h at room tempera-
ture propargyl bromide (80% in toluene, 2 g, 14 mmol) was
added and stirring was continued for a further 2 h at the
same temperature. The mixture was diluted with Et2O
(30 ml) and water (50 ml) was added. The organic layer
was separated, dried (MgSO4), ®ltered and evaporated in
vacuo yielding a thick yellow oil, which was puri®ed by
column chromatography eluting with 9:1 v/v n-hexane±
ethyl acetate affording 1.5 g (81%) of 2d as thick yellow
oil. (Found: C, 77.2; H, 6.8; N, 7.4. C12H13NO requires: C,
77.0; H, 6.95, N, 7.5%); d 2.18 (s, 3H, CH3), 2.20 (t,
Jˆ2.5 Hz, 1H, CHxC), 4.64±4.71 (m, 4H, 2£CH2N) and
7.15±7.68 (m, 5H, ArH); m/z (%) 187 (M1, 8), 149 (21),
148 (20), 106 (84), 91 (24), 51 (15), 44 (36) and 43 (100).
1.2.2. Methyl (2S)-2-{2-[2-(1-benzyl)-3-methyl-2,3-dihy-
dro-1H-3-indolyl)acetyl]allyl(phenyl)sulphonamido}-
propanoate, 4b. Viscous pale yellow oil. (Found: C, 66.2;
H, 5.8; N, 4.7; S, 5.85. C31H32N2O6S requires: C, 66.4; H,
5.75, N, 5.0; S, 5.7%); d (mixed diastereomers) 1.15 and
1.18 (2£d, Jˆ7 Hz, 3H, CH3), 1.25 and 1.27 (2£s, 3H,
CH3CCO), 3.29 and 3.36 (2£s, 3H, CH3O), 3.39±3.58 (m,
2H, CH2CO), 3.81±4.04 (m, 2H, CH2NAr), 4.53±4.64 (m,
1H, NCHCO2), 4.87, 5.09 (m, 2H, NCHPh), 6.23±6.32 (m,
2H, CH2yC) and 6.68±7.75 (m, 14H, ArH); m/z (%) 560
(M1, 12), 419 (54), 236 (54), 91 (100) and 77 (49).
1.1.3. N-Propargylsuccinimide, 2e. Sodium hydride (95%
powder, 177 mg, 7 mmol) was slowly added to a solution of
succinimide (0.69 g, 7 mmol) in dry DMF (10 ml). After 2 h
at room temperature propargyl bromide (80% in toluene,
2 g, 14 mmol) was added and stirring was continued for a
further 2 h at the same temperature. The mixture was diluted
with Et2O (30 ml) and water (50 ml) was added. The organic
layer was separated, dried (MgSO4), ®ltered and evaporated
in vacuo yielding a thick yellow oil, which was puri®ed by
column chromatography eluting with 1:1 v/v n-hexane±
ethyl acetate affording 0.84 g (87%) of 2e as thick yellow
oil. (Found: C, 61.25; H, 5.2; N, 10.25. C7H7NO2 requires:
C, 61.3; H, 5.15; N, 10.2%); d 2.20 (t, Jˆ2.5 Hz, 1H,
CHxC), 2.78 (s, 4H, 2£CH2CO), 4.34 and 4.20 (deform.
2£dd, Jˆ19.0 and 2.5 Hz, 2H, CH2N); m/z (%) 137 (M1,
13), 109 (29), 95 (100), 80 (18), 56 (28), 55 (26), 54 (25), 52
(26) and 39 (36).
1.2.3. Methyl (2S)-2-{2-[2-(3-methyl-1-phenylsulphonyl-
2,3-dihydro-1H-3-indolyl)acetyl]allyl(phenyl)sulphona-
mido}propanoate, 4c. Viscous pale brown oil. (Found: C,
60.5; H, 5.45; N, 4.6; S, 10.5. C30H32N2O7S2 requires: C,
60.4; H, 5.4; N, 4.7; S, 10.7%); d (mixed diastereomers)
1.16, 1.17 (2£s, 3H, CH3CCH2N), 1.29 (d, Jˆ7.3 Hz, 3H,
Me), 2.51, 2.65, 3.00 and 3.1 (4£d, Jˆ17.0 Hz, 2H,
CCH2CO), 3.40 (s, 3H, OMe), 3.77±4.20 (m, 4H,
CyCCH2N and CH2NAr), 4.65 (q, Jˆ7.6 Hz, 1H,
NCHCO2), 6.00, 6.03, 6.20 and 6.21 (4£s, 2H, CH2yC)
and 7.00±7.84 (m, 14H, ArH); m/z (%) 596 (M1, 15), 271
(40), 184 (59), 130 (55), 77 (83) and 57 (100).
1.2.4. Methyl 4-methyl-2-{2-[2-(3-methyl-1-phenylsul-
phonyl-2,3-dihydro-1H-3-indolyl)acetyl]allyl(phenyl)-
sulphonamido}pentanoate, 4d. Viscous pale yellow oil.
(Found: C, 61.9; H, 6.1; N, 4.15; S, 10.2. C33H38N2O7S2
requires: C, 62.0; H, 6.0; N, 4.4; S, 10.4%); d (mixed
diastereomers) 0.87 and 0.93 (2£d, Jˆ5.2 Hz, 6H, 2£Me),
1.16 (s, 3H, Me), 1.25±1.43 (m, 1H, Me2CH), 1.54±1.59
(m, 2H, CH2), 2.51, 2.62, 3.04 and 3.11 (4£d, Jˆ17.5 Hz,
2H, CH2CO), 3.37 (s, 3H, OMe), 3.82, 3.86, 3.95 and 3.99
(4£d, Jˆ11.2 Hz, 2H, CyCCH2N), 4.10 (s, 2H, CH2NAr),
4.53 (t, Jˆ6.0 Hz, 1H, NCH), 6.02, 6.05, 6.20 and 6.21
(4£s, 2H, CH2yC) and 7.01±7.85 (m, 14H, ArH); m/z (%)
639 (M111, 23), 272 (100), 131 (52) and 81 (45).
1.2. General procedure for 4a±l
Tri-n-butyltin hydride (0.150 ml, 0.5 mmol) was added
dropwise to a stirred solution of propargylic derivative 2
(0.5 mmol), Pd2dba3 (11.2 mg, 0.025 mmol) and tri-(2-
furyl)phosphine (11.6 mg, 0.10 mmol) in anhydrous toluene
(5 ml) cooled at 08C. The reaction mixture was stirred at
room temperature for 1 h before a solution of 1 (0.5 or
1 mmol, see Table 1) dissolved in toluene (2 ml) was
added. The reaction mixture was then saturated with carbon
monoxide (1 atm, balloon) and heated at 90±1008C with
stirring for the times indicated on Table 1. The reaction
mixture was cooled and a saturated aqueous solution of
1.2.5. Methyl 4-methyl-2-{2-[2-(3-methyl-2,3-dihydro-
benzo[b]furan-3-yl)acetyl]allyl(phenyl)sulphonamido}-
pentanoate, 4e. Viscous pale yellow oil. (Found: C, 65.0;
H, 6.65; N, 2.7; S, 6.35. C27H33NO6S requires: C, 65.0; H,

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U. Anwar et al. / Tetrahedron 57 (2001) 1361±1367
6.65; N, 2.8; S, 6.4%); d (mixed diastereomers) 0.85±0.94
(m, 6H, 2£Me), 1.25±1.37 (m, 1H, Me2CH), 1.41±1.43
(2£s, 3H, Me), 1.53±1.65 (m, 2H, CH2), 2.93±3.28 (m,
2H, CH2CO), 3.35 and 3.37 (2£s, 3H, MeCO), 4.14 (s,
2H, CH2N), 4.46 (s, 2H, CH2O), 4.50±4.57 (m, 1H,
NCHCO2Me), 6.22 and 6.28 (2£s, 2H, CyCH2) and 6.79±
7.86 (m, 9H, ArH); m/z (%) 499 (M1, 11), 440 (80), 358
(55), 226 (64) and 133 (100).
1.2.11. 3,9-Dimethyl-1-{2-[2-(3-methyl-2,3-dihydrobenzo-
[b]furan-3-yl)acetyl]allyl}-2,3,6,9-tetrahydro-1H-2,6-
purine dione, 4k. Colourless prisms, mp 788C (from petro-
leum ether±ether); d 1.43 (s, 3H, CCH3), 3.00, 3.38 (2£d,
Jˆ3.0 Hz, 2H, CH2O), 3.58, 3.98 (2£s, 6H, 2£NCNCH3),
4.48, 4.50 (2£d, Jˆ4.5 Hz, 2H, CyCCH2N), 4.84 (s, 2H,
CH2CO), 5.50, 6.00 (2£s, 2H, CyCH2), 6.70±7.20 (m, 4H,
ArH) and 7.60 (s, 1H, NCHN); m/z (%) 394 (M1, 12), 379
(21), 262 (44) and 219 (100). Accurate mass found:
394.1649. C21H20N4O2 requires: 394.1641.
1.2.6. N-1-Benzyl-N-1-{2-[2-(3-methyl-1-phenylsulpho-
nyl-2,3-dihydro-1H-3-indolyl)acetyl]allyl}acetamide, 4f.
Viscous pale yellow oil. (Found: C, 69.2; H, 6.3; N, 5.4.
C29H30N2O4S requires: C, 69.3; H, 6.0; N, 5.2%); d
(rotomers) 1.43 and 1.61 (2£s, 3H, Me), 2.09 and 2.16
(2£s, 3H, Me), 2.09 and 2.16 (2£s, 3H, MeCO), 2.56,
2.65, 2.97 and 3.04 (4£d, Jˆ17.0 Hz, 2H, CH2CO), 3.66
and 3.77 (2£d, 1H of CH2NCH2), 3.92±4.15 (m, 3H of
CH2NCH2), 4.50 (m, 2H, CH2N), 5.66, 5.77, 5.90 and
5.92 (4£s, 2H, CH2yC) and 6.99±7.85 (m, 14H, Ar); m/z
(%) 503 (M111, 15), 459 (19), 272 (24), 188 (60), 130 (45),
91 (100) and 77 (60).
1.2.12. 3-[(3-Methyl-1-phenylsulphonyl-2,3-dihydro-1H-
3-indolylmethyl)-3-buten-2-one, 4l. Colourless prisms, mp
114±1178C (from petroleum ether±ether). (Found; C,
67.55; H, 6.1; N, 3.65; S, 9.0. C20H21NO3S requires: C,
67.6; H, 6.0; N, 3.9; S, 9.0%); d 1.15 (s, 3H, Me), 2.21 (s,
3H, OMe), 2.33 and 2.69 (2£d, 2H, Jˆ13.1 Hz, CH2), 3.31
and 3.90 (2£d, 2H, CH2N), 5.34, 5.85 (2£s, 2H, CH2yC)
and 6.99±7.85 (m, 9H, ArH); m/z (%) 355 (M1, 30), 272
(100), 141 (51), 130 (80) and 84 (77).
1.2.13. Methyl 2-[(E)-5-(3-methyl-1-phenylsulphonyl-
2,3-dihydro-1H-3-indolyl)-4-oxo-2-pentenyl(phenyl)-
sulphonamido]acetate, 9. Compound 9 was synthesized
using the same procedure as that described for the synthesis
of compounds 4 but this time the vinylstannane was
prepared previously according to the literature.10 After 6 h
at 908C extractive work-up and puri®cation (SiO2) eluting
with mixtures v/v 3:1 of petroleum ether±ether, product 9
was obtained as pale yellow oil. (Found: C, 59.7; H, 5.2; N,
4.5; S, 11.0. C29H30N2O7S2 requires: C, 59.75; H, 5.2; N,
4.8; S, 11.0%); d 1.17 (s, 3H, CH3C), 2.40, 2.79 (2£d,
Jˆ17.0 Hz, 2H, CCH2CO), 3.59 (s, 3H, CH3O), 3.75, 3.96
(2£d, Jˆ11.1 Hz, 1H, CH2NAr), 3.98 (s, 2H, NCH2CO),
6.48 (d£t, Jˆ16.0 and 5.4 Hz, 1H, CHyCHCO) and 6.99±
7.87 (m, 14H, ArH); m/z (%) 582 (M1, 1), 272 (55), 271
(100), 168 (28), 144 (30), 141 (40), 131 (26), 130 (76), 78
(28), 77 (98) and 51 (42).
1.2.7. 1-{2-[2-(3-Methyl-2,3-dihydrobenzo[b]furan-3-yl)-
acetyl]allyl}-2,5-pyrrolidine dione, 4g. Colourless prisms
137±1408C (from petroleum ether±ether). (Found: C, 69.0;
H, 6.15; N, 4.2. C18H17O4N requires: C, 69.3; H, 6.0; N,
4.5%); d 1.42 (s, 3H, Me), 2.76 (s, 4H, CH2CH2), 2.96
and 3.28 (4£d, Jˆ17.3 Hz, 2H, CH2CO), 4.34 (s, 2H,
CH2N), 4.45 (s, 2H, CH2O), 5.60 and 6.04 (2£s, 2H,
CH2yC) and 6.79±7.26 (m, 4H, ArH); m/z (%) 313 (M1,
15), 132 (41), 100 (100), 92 (19), 77 (34) and 56 (67).
1.2.8. 1-(3-Methyl-2,3-dihydrobenzo[b]furan-3-yl)-3-(2-
pyridyl)-3-buten-2-one, 4h. Viscous pale yellow oil.
(Found: C, 77.25; H, 6.2; N, 4.8. C18H17NO2 requires: C,
77.3; H, 6.1; N, 5.0%); d 1.46 (s, 3H, CH3), 2.98 and 3.26
(2£d, Jˆ17 Hz, 2H, CH2CO), 4.47 and 4.56 (2£d,
Jˆ9.0 Hz, 2H, CH2CO), 6.80±7.75 (m, 7H, ArH and
CH2yC) and 8.56 (d, 1H, ArH); m/z (%) 279 (M1, 12),
132 (34), 103 (31), 92 (14), 91 (10), 78 (16), 77 (23) and
55 (43).
Acknowledgements
1.2.9. 1-{2-[2-(3-Methyl-2,3-dihydrobenzo[b]furan-3-yl)-
acetyl]allyl}-1,2-dihydro-2-pyridone, 4i. Colourless oil.
(Found: C, 73.85; H, 6.3; N, 4.6. C19H19NO3 requires: C,
73.75; H, 6.2; N, 4.5%); d 1.38 (s, 3H, CH3), 2.95 and 3.25
(2£d, Jˆ17 Hz, 2H, CH2O), 4.39 and 4.46 (2£d, Jˆ9.0 Hz,
2H, CH2N), 4.68 and 4.73 (2£d, Jˆ15 Hz, 2H, CH2O), 5.92
(s, 1H, CHyC), 6.12±6.18 (m, 2H, ArH and CHyC), 6.12±
6.18 (m, 2H, ArH and CHyC), 6.55 (d, 1H, ArH) and 6.76±
7.36 (m, 6H, ArH); m/z (%) 310 (M111, 100), 214 (83), 177
(65), 134 (97) and 105 (55).
We thank the EPSR, the Spanish Government (MEC) and
the EU Human Capital and Mobility Scheme and Leeds
University for support.
References
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1.2.10. 1-{2-[2-(1,3-Dimethyl-2,3-dihydro-1H-3-indolyl)-
acetyl}allyl-3,9-dimethyl-2,3,6,9-tetrahydro-1H-2,6-
purine dione, 4j. Colourless prisms, mp 888C (from petro-
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Â
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