A New Platinum Complex Catalyzed Reaction Involving Nucleophilic Substitution at the Central Carbon Atom of the π-Allyl Ligand

Article abstract of DOI:10.1021/jo990845x

The reaction of 2-chloro-allyl acetate with sodium ethyl acetoacetate in the presence of a platinum-(0) complex gave furan derivatives. The key feature of this new platinum-catalyzed reaction is the nucleophilic substitution at the central carbon atom of π-allyl complexes. The regioselectivity of the nucleophilic attacks (central or terminal) is dependent on the pK_a of the nucleophile. In addition, a labeling experiment revealed that a rapid syn-anti isomerization of the (π-allyl) platinum complexes occurs.

Full text of DOI:10.1021/jo990845x

J . Org. Chem. 1999, 64, 7523-7527
7523
A New P la tin u m Com p lex Ca ta lyzed Rea ction In volvin g
Nu cleop h ilic Su bstitu tion a t th e Cen tr a l Ca r bon Atom of th e
π-Allyl Liga n d
J oji Kadota, Shinji Komori, Yoshiya Fukumoto, and Shinji Murai*
Department of Applied Chemistry, Faculty of Engineering, Osaka University,
Suita, Osaka 565-0871, J apan
Received May 24, 1999
The reaction of 2-chloro-allyl acetate with sodium ethyl acetoacetate in the presence of a platinum-
(0) complex gave furan derivatives. The key feature of this new platinum-catalyzed reaction is the
nucleophilic substitution at the central carbon atom of π-allyl complexes. The regioselectivity of
the nucleophilic attacks (central or terminal) is dependent on the pKa of the nucleophile. In addition,
a labeling experiment revealed that a rapid syn-anti isomerization of the (π-allyl) platinum
complexes occurs.
Sch em e 1
In tr od u ction
The extensive investigations of reactions of π-allyl
transition metal complexes with nucleophiles has led to
a number of synthetically useful methods for the intro-
duction of three-carbon units into organic compounds.
Typically, the nucleophilic attack takes place at the
terminal carbon atom of π-allyl complexes to give ally-
lated products.1 The recent report of a nucleophilic attack
at the central carbon atom of π-allyl complexes has
attracted attention. This process converts π-allyl com-
plexes into a variety of metalacyclobutanes2 and, in some
cases, leads to the formation of cyclopropane derivatives
via reductive elimination with metallacyclobutanes.3 In
the majority of these examples, the attached group on
the central carbon atom was a hydrogen atom and, in a
few cases, an alkyl group. If, however, group X (Scheme
1) represents a viable leaving group, this could substan-
tially alter the reaction pathway. Thus, nucleophilic
substitution would be expected to proceed via nucleophilic
attack at the central carbon atom of the π-allyl complex
(I) followed by the elimination of X- from metalacyclobu-
tane (II), rather than cyclopropane, giving rise to a
reductive elimination.
In a preliminary communication we reported the first
example of this type of reaction.4 In the presence of a
platinum catalyst, the reaction of 2-chloro-allyl acetate
with 2 equiv of sodium diethyl methylmalonate gave a
doubly alkylated product, and in the case of sodium ethyl
benzoyl acetate, a furan derivative was obtained. More
recently, three examples of nucleophilic substitutions of
this type at the central carbon atom have been reported
by other groups. Ba¨ckvall reported the stoichiometric
reaction of (π-allyl) palladium complexes with sodium
diethyl methylmalonate,5 and Chen reported the forma-
tion of trimethylenemethane platinum complexes.6 Organ
reported the palladium-catalyzed reaction of 2,3-dibro-
mopropene with phenoxides as nucleophiles.7 In this
paper, we report further results of the platinum-catalyzed
reaction of 2-chloro-allyl acetate with a variety of carbon
nucleophiles. Our findings show that the regioselectivity
of the nucleophilic attack on the central or terminal
carbon is dependent on the nature of the nucleophiles
used.
(1) Trost, B. M.; Verhoven, T. R. In Comprehensive Organometallic
Chemistry; Wilkinson, G., Stone, F. G., Abel, E. W., Eds.; Pergamon
Press: Oxford, U.K., 1982; Vol. 8, p 799.
(2) (a) Ephritikhine, M.; Green, M. L. H.; Mackenzie, R. E. J . Chem.
Soc., Chem. Commun. 1976, 619. (b) Ephritikhine, M.; Francis, B. R.;
Green, M. L. H.; Mackenzie, R. E.; Smith, M. J . J . Chem. Soc., Dalton
Trans. 1977, 1131. (c) Adam, G. J . A.; Davies, S. G.; Ford, K. A.;
Ephritikhine, M.; Todd, P. F.; Green, M. L. H. J . Mol. Catal. 1980, 8,
15. (d) Periana, R. A.; Bergman, R. G. J . Am. Chem. Soc. 1984, 106,
7272. (e) McGhee, W. D.; Bergman, R. G. J . Am. Chem. Soc. 1985,
107, 3388. (f) Periana, R. A.; Bergman, R. G. J . Am. Chem. Soc. 1986,
108, 7346. (g) Tjaden, E. B.; Stryker, J . M. J . Am. Chem. Soc. 1990,
112, 6420. (h) Wakefield, J . B.; Stryker, J . M. J . Am. Chem. Soc. 1991,
113, 7057. (i) Tjaden, E. B.; Stryker, J . M. Organometallics 1992, 11,
16. (j) Tjaden, E. B.; Schwiebert, K. E.; Stryker, J . M. J . Am. Chem.
Soc. 1992, 114, 1100. (k) Schwiebert, K. E.; Stryker, J . M. Organome-
tallics 1993, 12, 600. (l) Tjaden, E. B.; Stryker, J . M. J . Am. Chem.
Soc. 1993, 115, 2083.
Resu lts a n d Discu ssion
2-Chloro-allyl acetate 1 was chosen as the simplest
(3) (a) Hegedus, L. S.; Danlington, W. H.; Russell, C. E. J . Org.
Chem. 1980, 45, 5193. (b) Carfagna, C.; Maniani, L.; Musco, A.; Sallese,
G.; Santi, R. J . Org. Chem. 1991, 56, 3924. (c) Carfagna, C.; Galarini,
R.; Musco, A.; Santi, R. Organometallics 1991, 10, 3956. (d) Hoffmann,
H. M. R.; Otte, A. R.; Wilde, A. Angew. Chem., Int. Ed. Engl. 1992, 31,
234. (e) Wilde, A.; Otte, A. R.; Hoffmann, H. M. R. J . Chem. Soc., Chem.
Commun. 1993, 615. (f) Formica, M.; Musco, A.; Pontellini, R.; Linn,
K.; Mealli, C. J . Organomet. Chem. 1993, 448, C6. (g) Carfagna, C.;
Galarini, R.; Linn, K.; Lo´pez, J . A.; Mealli, C.; Musco, A. Organome-
tallics 1993, 12, 3019. (h) Hoffmann, H. M. R.; Otte, A. R.; Wilde, A.;
Menzer, S.; Williams, D. J . Angew. Chem., Int. Ed. Engl. 1995, 34,
100. (i) Satake, A.; Nakata, T. J . Am. Chem. Soc. 1998, 120, 10391. (j)
Satake, A.; Koshino, H.; Nakata, T. Chem. Lett. 1999, 49.
allyl acetate with a leaving group on the central carbon.
(4) Ohe, K.; Matsuda, H.; Morimoto, T.; Ogoshi, S.; Chatani, N.;
Murai, S. J . Am. Chem. Soc. 1994, 116, 4125.
(5) (a) Castan˜o, A. M.; Aranyos, A.; Szabo´, K. J .; Ba¨ckvall, J . E.
Angew. Chem., Int. Ed. Engl. 1995, 34, 2551. (b) Aranyos, A.; Szabo´,
K. J .; Castan˜o, A. M.; Ba¨ckvall, J . E. Organometallics 1997, 16, 1058.
(6) Tsai, F.-Y.; Chen, H.-W.; Chen, J .-T.; Lee, G.-H.; Wang, Y.
Organometallics 1997, 16, 822.
(7) (a) Organ, M. G.; Miller, M. Tetrahedron Lett. 1997, 38, 8181.
(b) Organ, M. G.; Miller, M.; Konstantinou, Z. J . Am. Chem. Soc. 1998,
120, 9283.
10.1021/jo990845x CCC: $18.00 © 1999 American Chemical Society
Published on Web 09/14/1999

7524 J . Org. Chem., Vol. 64, No. 20, 1999
Kadota et al.
Ta ble 1. Va r ia tion of Liga n d s
Ta ble 2. P la tin u m -Ca ta lyzed Rea ction of 2-Ch lor o-a llyl
Aceta tes w ith Ca r bon Nu cleop h ilesa
yield (%)a
entry
ligand
time (h)
of 5
1
2
3
4
5
6
7
PPh3
P(OMe)3
dppe
dppb
dppf
2
8
85(83b)
73
21
18
28
20
18
n.r.c
20d
61d
n.r.
n.r.
TMEDA
bipy
a
d
GC yield. b Isolated yield. c No reaction. Allyl acetate was not
consumed completely.
The reaction of 1 with sodium diethyl malonate 2 in the
presence of a platinum complex such as Pt(C2H4)(PPh3)2
resulted in no reaction.8 In contrast, however the reaction
of 2-chloro-allyl acetate 1 (1.0 mmol) with 2 equiv of
sodium ethyl acetoacetate 3 in the presence of Pt(C2H4)-
(PPh3)2 (0.1 mmol) as catalyst in THF at reflux gave ethyl
2,4-dimethyl-3-furoate 5 as the result of a nucleophilic
attack at the central carbon (eq 1).
This reaction proceeds as follows. First, a nucleophilic
attack at the central carbon atom of 2-chloro-(π-allyl)
platinum(II) 6 gives platinacyclobutane 7. The elimina-
tion of a chloride anion in 7, followed by deprotonation
by the excess nucleophile, which serves as a base, affords
2-alkylated (π-allyl) platinum(II) 8. (In fact, it must also
exist in trimethylenemethane-platinum form.) An eno-
late O-cyclization, followed by exo to endo double-bond
isomerization would have given furan 5.9
a
Reactions were run as follows: protonated nucleophile (2.0
Several different ligands for platinum(0) were exam-
ined in this reaction (eq 1) using platinum complexes
prepared in situ from Pt(dba)2 (10 mol %) and an
appropriate ligand (20 mol % for the monodentate, 10
mol % for the bidentate) as catalyst instead of Pt(C2H4)-
(PPh3)2 (Table 1). The use of PPh3 gave the highest yield
(entry 1). Platinum-bidentate phosphine ligand systems,
such as Pt(dba)2-dppe, -dppb, and -dppf, gave moder-
ate to poor yields (entries 3-5). No reaction was observed
with σ-donor nitrogen ligands, such as TMEDA or bipy-
ridyl, although some nitrogen ligands have been reported
to be effective for the attack on a central carbon.5
With Pt(C2H4)(PPh3)2 (10 mol %) as the catalyst,
reactions of 1,3-substituted allyl acetates (1.0 mmol) with
some carbon nucleophiles (2.0 mmol) were carried out
under the same condition as were used for the reaction
of eq 1. These results are summarized in Table 2.
mmol) was added to a suspension of NaH (2.0 mmol) in THF at 0
°C. After the solution was stirred for 30 min at room temperature,
Pt(C2H4)(PPh3)2 (0.1 mmol) and allyl acetate (1.0 mmol) were
b
added. In refluxing dioxane. No reaction in THF. c This product
underwent isomerization within 30 min in CDCl3 to the corre-
sponding furan derivative.
Allyl acetate 1 reacted with sodium acetylacetonate 13
to give a furan derivative 14 in dioxane at reflux, whereas
no reaction took place in refluxing THF (entry 2). The
reaction of 3-phenylallyl acetate 9 with sodium ethyl
acetoacetate 3 gave the 2,3-dihydrofuran derivative 15,
which was formed through enolate O-cyclization at the
terminal carbon atom, which carries a phenyl group in
π-allyl ligand (entry 3). It is likely that the regioselectivity
of enolate O-cyclization onto C1 or C3 termini is depend-
ent on the stabilization of the partial positive charge on
the terminal carbon, in this case, the phenyl group. The
reactions of 1-methyl-3-phenylallyl acetate 10 with nu-
cleophiles were also examined (entries 4-6). Interest-
ingly, with nucleophiles bearing an acetyl group, the
corresponding dihydrofurans 16 and 17 were obtained.
The cyclization took place at the terminal carbon carrying
the smaller substituent, i.e., a methyl group. Thus, steric
(8) The lack of reaction appears to be due to stable trimethylene-
methane-plainum complex formation through nucleophilic substitu-
tion at the central carbon atom of the π-allyl ligand, followed by
deprotonation. Actually, the stoichiometric reaction of 2-chloro-(π-allyl)
platinum complex with sodium diethyl malonate gave a trimethylene-
methane-platinum complex in 21% yield.
(9) A preliminary result of a similar reaction using sodium ethyl
benzoyl acetate has been reported; see ref 4.

Nucleophilic Substitution of the π-Allyl Ligand
J . Org. Chem., Vol. 64, No. 20, 1999 7525
congestion appears to compete with phenyl stabilization.
It is noteworthy that sodium diethyl malonate 2 did not
undergo attack at the central carbon atom but attacked
at the terminal carbon atom in a classic manner (entry
6). A similar result was obtained in the reaction where
1,3-diphenylallyl acetate 12 was used as the substrate
(entry 10). At present, the reason for why the regiose-
lectivity of nucleophilic attack (central or terminal) varies
with the nature of the nucleophile used is unclear.
Recently, Ba¨ckvall has reported that the site of nucleo-
philic attack (central or terminal) in the reaction of a
2-chloro-(π-allyl) palladium complex with carbon nucleo-
philes changed with the type of ligand.5 Central attack
was observed when bipyridyl or TMEDA was used as the
ligand, but terminal attack occurred with a phosphine
ligand. Calculation for (π-allyl) palladium complexes with
the σ-donor nitrogen ligands indicated that the LUMO
is the molecular orbital with a large coefficient at the
central carbon. They proposed that the nucleophilic
attack at the central carbon is frontier orbital controlled.
However, the data herein suggest that the regioselectivity
of nucleophilic attack on (π-allyl) platinum complexes
varies with the structure of the nucleophiles. It seems
likely that the energy level of the nucleophile’s HOMO
also is a factor in determining whether the central or
terminal carbon atom of the π-allyl ligand is attacked.
Thus, when the difference of energy level between the
nucleophile’s HOMO and LUMO of π-allyl complexes is
sufficiently small to allow the interaction of molecular
orbitals, central attack will be observed. The pKa values
for 13, 3, and 2 are 9, 11, and 13, respectively, and relate,
in part, to the strength of their nucleophilicity. To make
the relation of regioselectivities with the pKa values
clearly, cyclic â-dicarbonyls (1,3-cyclohexanedione, Mel-
drum’s acid) were used but unfortunately resulted in no
reaction.
Con clu sion
The data herein provide clear evidence for the platinum-
catalyzed reaction of 2-chloro-allyl acetate with stabilized
carbon nucleophiles. This reaction is a new type of
catalytic reaction, in which the nucleophilic substitution
at the central carbon atom of π-allyl complexes predomi-
nates. The site of nucleophilic attack on either the central
or terminal carbon atom appears to depend on the small
difference in the pKa of the nucleophiles.
Exp er im en ta l Section
Ma ter ia ls. Protonated nucleophiles, diethyl malonate 2,
ethyl acetoacetate 3, and acetylacetone 13, were purificated
by distillation. THF and dioxane were distilled over Na-
benzophenone or CaH prior to use. Pt(C2H4)(PPh3)2 and Pt-
(dba)2 were prepared according to published procedures.
11
12
P r ep a r a tion of 2-Ch lor o-a llyl Aceta tes. 2-Ch lor o-2-
p r op en yl Aceta te (1). A mixture of 2,3-dichloro-1-propene
(11.1 g, 100 mmol) and K2CO3 (15.2 g, 110 mmol) in water
(100 mL) was stirred at reflux temperature for 12 h. After
cooling to room temperature, the mixture was extracted with
diethyl ether, and the combined organic layer was dried over
MgSO4 and concentrated in vacuo to give a yellow oil. The
residue was distilled under atmospheric pressure to give
2-chloro-2-propen-1-ol (8.51 g, 92 mmol, bp 127-129 °C). To a
mixture of this alcohol (8.51 g) and triethylamine (40 mL, 287
mmol) in diethyl ether (100 mL) at 0 °C was added acetyl
chloride (14.2 mL, 200 mmol) dropwise, and the resulting
solution was stirred at room temperature for 1 h. After 2 N
HCl (200 mL) was added to the reaction mixture, it was
extracted with diethyl ether, and the combined organic layer
was dried over MgSO4 and concentrated in vacuo to give a
yellow oil. The residue was distilled under reduced pressure
to give 2-chloro-2-propenyl-acetate 1 (8.34 g, 62 mmol, overall
62% yield, bp 79-80 °C/100 mmHg). This material is also
commercially available (Aldrich Chemical Co. 29077-7).
2-Ch lor o-3-p h en yl-2-p r op en yl Aceta te (9). First, 2 N
HCl (30 mL) was added dropwise to a solution of R-chlorocin-
namaldehyde (8.33 g, 50 mmol) and NaBH3CN (7.54 g, 120
mmol) in methanol (100 mL) at room temperature, followed
by stirring for 1 h.13 The reaction mixture was concentrated
in vacuo, the residue was extracted with diethyl ether, and
the combined organic layer was dried over MgSO4 and
concentrated in vacuo. The residue was purified by column
chromatography on silica gel (eluent, hexane/ethyl acetate )
10/1) to give 2-chloro-3-phenyl-2-propen-1-ol (4.45 g, 26.4
mmol). This alcohol was acetylated as described for 1 (3.81 g,
18 mmol, overall 36% yield) to give a white solid, mp 44-45
The reaction with 1-phenyl-3-methylallyl acetate 11
(which is an isomer of 10 with a reversed substitution
pattern) afforded the same product 16 (entries 7 and 4).
It thus appears that the product was obtained via a
common π-allyl intermediate, derived from both 10 and
11, and this suggests that the syn-anti stereochemistry
in the intermediate is easily interconvertible.10
Similar results relative to regio- and stereochemistry
were obtained for the symmetrically substituted allyl
aceates that were unsymmetrically labeled (22 and 23).
The deuterium was incorporated equally into the two
substituents (eq 2 and 3).
1
°C, bp 102 °C/2 mmHg. H NMR (CDCl3): δ 2.15 (s, 3H), 4.81
(s, 2H), 6.78 (s, 1H), 7.28-7.41 (m, 3H), 7.64 (m, 2H). 13C NMR
(CDCl3): δ 20.8, 68.5, 127.5, 128.3, 128.3, 128.4, 129.2, 133.7,
170.3. IR (KBr): 2944 bw, 1734 s cm-1. MS (70 eV): m/z
(relative intensity, %) 212 (M+ + 2, 4), 210 (M+, 12), 168 (18),
115 (100), 77 (15). HRMS Found: 210.0437. Calcd for C11H11O2-
Cl: 210.0448.
2-Acetoxy-3-ch lor o-4-p h en yl-3-bu ten e (10). To the Grig-
nard reagent MeMgI [prepared in situ from Mg (1.46 g, 60
mmol) and iodomethane (8.52 g, 60 mmol)] in diethyl ether
(100 mL) at room temperature was added a diethyl ether
(10) We consider that the elimination of
a chloride anion in
intermediate 7 requires flipping of 7. The reactions of cyclic allyl
acetate (2-chloro-2-cyclohexenyl acetate, which is not able to flip in
intermediate 7) with carbon nucleophiles from diethyl malonate 2,
ethyl acetoacetate 3, and acetylacetone 13 were investigated, and in
the case of 2 and 13, only terminal attack leading to allylation was
observed as expected. However, only in the case of sodium ethyl
acetoacetate 3 as nucleophile, product by central attack was observed
in 13% yield, with allylated product in 73% yield (not identified except
for 1H NMR spectrum). This result is not understood as of now and
must be investigated in detail.
(11) Cook, C. D.; J auhal, G. S. J . Am. Chem. Soc. 1968, 90, 1464.
(12) Maitlis, P. M.; Moseley, K. J . Chem. Soc., Chem. Commun.
1971, 982.
(13) Hutchins, R. O.; Kandasamy, D. J . Org. Chem. 1975, 40, 2530.

7526 J . Org. Chem., Vol. 64, No. 20, 1999
Kadota et al.
solution of R-chlorocinnamaldehyde (5.0 g, 30 mmol). The
mixture was stirred for 12 h, and a saturated aqueous solution
(100 mL) of NH4Cl was added, followed by extraction with
diethyl ether. The combined organic layer was dried over
MgSO4 and concentrated in vacuo. The residue was distilled
under reduced pressure to give 3-chloro-4-phenyl-3-buten-2-
ol (5.10 g, 28 mmol). This alcohol was acetylated as described
for 1 in an overall yield of 90% (6.10 g, 27 mmol) to give a
colorless liquid, bp 80 °C/0.1 mmHg. 1H NMR (CDCl3): δ 1.51
(d, J ) 6.3 Hz, 3H), 2.11 (s, 3H), 5.59 (q, J ) 6.3 Hz, 1H), 6.78
(s, 1H), 7.29-7.39 (m, 3H), 7.60 (m, 2H). 13C NMR (CDCl3): δ
19.0, 21.2, 73.7, 126.6, 128.2, 128.3, 129.4, 132.5, 133.9, 170.0.
IR (neat): 2990 m, 1746 bs cm-1. MS (70 eV): m/z (relative
intensity, %) 226 (M+ + 2, 1.5), 225 (M+ + 1, 0.8), 224 (M+,
5.3), 189 (11), 129 (100), 77 (14). Anal. Calcd for C12H13O2Cl:
C, 64.15; H, 5.83; Cl, 15.78. Found: C, 64.15; H, 5.83; Cl, 15.79.
1-Acetoxy-2-ch lor o-1-p h en yl-2-bu ten e (11). A solution
of trans-1-ethoxy-1-propene (10.4 g, 120 mmol) and bromot-
richloromethane (24 g, 120 mmol) in diethyl ether (50 mL) was
cooled to -78 °C. To this stirred solution was added methyl-
lithium (1.0 M in diethyl ether, 150 mL, 150 mmol) dropwise
over a 1 h period. After 1 h at the same temperature, water
(50 mL) was added. The resulting solution was extracted with
diethyl ether, and the combined ether layer was dried over
MgSO4. The ether was evaporated, and the residue was
distilled under reduced pressure to give 1,1-dichloro-2-ethoxy-
3-methylcyclopropane14 (15.9 g, 94 mmol). trans-2-Chloro-1,1-
diethoxy-2-butene14 was prepared in 63% yield (10.5 g, 59
mmol) from 1,1-dichloro-2-ethoxy-3-methylcyclopropane and
sodium ethoxide [generated in situ from Na (2.81 g, 122 mmol)
and solvent ethanol] in ethanol (50 mL) at reflux for 12 h. This
acetal in 1 N HCl (50 mL) was stirred for 0.5 h at room
temperature. The mixture was extracted with pentane and
dried over MgSO4. Evaporation of the pentane followed by
distillation gave trans-2-chloro-2-butenal14 (5.85 g, 56 mmol).
This aldehyde was phenylated and acetylated in the same
manner as described for 10 using bromobenzene instead of
iodomethane in 99% yield (12.4 g, 55 mmol, overall 46% yield)
to give a colorless liquid, bp 95 °C/0.1 mmHg. 1H NMR
(CDCl3): δ 1.79 (d, J ) 6.6 Hz, 3H), 2.16 (s, 3H), 5.95 (q, J )
6.6 Hz, 1H), 6.38 (s, 1H), 7.32-7.38 (m, 5H). 13C NMR
(CDCl3): δ 13.8, 21.1, 77.4, 117.4, 124.8, 127.0, 128.4, 132.9,
137.0, 169.6. IR (neat): 2928 bm, 1748 bs cm-1. MS (70 eV):
m/z (relative intensity, %) 224 (M+, 0.5), 189 (12), 129 (100),
77 (23). Anal. Calcd for C12H13O2Cl: C, 64.15; H, 5.83; Cl,
15.78. Found: C, 63.93; H, 5.74; Cl, 15.76.
dehyde (3.83 g, 23 mmol) as a colorless liquid. Rf 0.23 (hexane/
ethyl acetate ) 10/1). 1H NMR (CDCl3): δ 2.20 (s, 3H), 6.52
(s, 1H), 6.89 (s, 1H), 7.29-7.40 (m, 3H), 7.63-7.66 (m, 2H).
13C NMR (CDCl3): δ 21.1, 78.1, 127.5, 128.2, 128.4, 129.4,
131.2, 133.8, 136.7, 169.5. IR (neat): 2940 w, 1752 bs, 1646 m
cm-1. MS (70 eV): m/z (relative intensity, %) 291 (M+, 1.1),
249 (12), 196 (100). HRMS Found: 291.1071. Calcd for
C17H10O2D5Cl: 291.1074.
Typ ica l P r oced u r e. Ethyl acetoacetate (260 mg, 2.0 mmol)
was added to a suspension of NaH (60 wt % in mineral oil, 80
mg, 2.0 mmol) in THF (10 mL) at 0 °C. The mixture was stirred
at room temperature for 30 min, at which time Pt(C2H4)(PPh3)2
(74.7 mg, 0.1 mmol) was added. 2-Chloro-allyl acetate 1 (134.5
mg, 1.0 mmol) was added, and the flask was then immersed
in an oil bath at 80 °C. The reaction was monitored by
analytical GC, and after 2 h the substrate had been completely
consumed. After the reaction mixture was cooled to room
temperature, water (10 mL) was added. The resulting solution
was extracted with diethyl ether, and the combined organic
layer was dried over MgSO4 and concentrated in vacuo to give
yellow oil. The residue was subjected to column chromatog-
raphy on silica gel (eluent, hexane/ethyl acetate ) 10/1) to give
ethyl 2,4-dimethyl-3-furoate 5 (101 mg, 62% yield) as a clear
oil.
Eth yl 2,4-Dim eth yl-3-fu r oa te (5): colorless liquid; bp 100
°C/16 mmHg. 1H NMR (CDCl3): δ 1.35 (t, J ) 7.1 Hz, 3H),
2.13 (d, J ) 1.4 Hz, 3H), 2.53 (s, 3H), 4.28 (q, J ) 7.1 Hz, 2H),
7.03 (d, J ) 1.4 Hz, 1H). 13C NMR (CDCl3): δ 10.0, 14.3, 59.8,
113.5, 121.2, 137.6, 160.0, 164.8. IR (neat): 2978 bm, 1724 bs,
1613 s cm-1. MS (70 eV): m/z (relative intensity, %) 169 (M+
+ 1, 60), 123 (100). Anal. Calcd for C9H12O3: C, 64.27; H, 7.19.
Found: C, 64.15; H, 7.39.
3-Acetyl-2,4-d im eth ylfu r a n (14): colorless liquid; bp 90-
95 °C/12 mmHg. 1H NMR (CDCl3): δ 2.16 (d, J ) 1.4 Hz, 3H),
2.42 (s, 3H), 2.54 (s, 3H), 7.02 (d, J ) 1.4 Hz, 1H). 13C NMR
(CDCl3): δ 10.7, 15.3, 30.9, 120.3, 122.4, 137.9, 159.1, 194.8.
IR (neat): 2964 m, 2930 m, 1670 s cm-1. MS (70 eV): m/z
(relative intensity, %) 140 (M+ + 2, 2), 139 (M+ + 1, 2), 138
(M+, 18), 123 (100). HRMS Found: 138.0681. Calcd for
C8H10O2: 138.0680.
4-Eth oxyca r bon yl-5-m eth yl-3-m eth ylen e-2-p h en yl-2,3-
d ih yd r ofu r a n (15): colorless liquid. Rf 0.28 (hexane/ethyl
1
acetate ) 10/1). H NMR (CDCl3): δ 1.35 (t, J ) 7.3 Hz, 3H),
2.40 (s, 3H), 4.28 (q, J ) 7.3 Hz, 2H), 4.53 (d, J ) 3.0 Hz, 1H),
5.53 (d, J ) 3.2 Hz, 1H), 5.94 (dd, J ) 3.0 Hz, J ) 3.2 Hz, 1H),
7.30-7.40 (m, 5H). 13C NMR (CDCl3): δ 14.3, 15.6, 59.8, 88.2,
101.2, 106.6, 127.3, 128.7, 128.8, 139.4, 147.0, 164.9, 175.5.
IR (neat): 2966 m, 1702 m, 1614 m cm-1. MS (70 eV): m/z
(relative intensity, %) 246 (M+ + 2, 2), 245 (M++1, 18), 244
(M+, 100), 216 (23), 77 (55). HRMS Found: 244.1100. Calcd
for C15H16O3: 244.1099.
2-Ch lor o-1,3-d ip h en yl-2-p r op en yl Aceta te (12). The use
of bromobenzene instead of iodomethane in the same manner
as described for 10 gave 12 in 98% yield (7.22 g, 29.5 mmol)
1
as a colorless liquid. Rf 0.23 (hexane/ethyl acetate ) 10/1). H
NMR (CDCl3): δ 2.20 (s, 3H), 6.52 (s, 1H), 6.88 (s, 1H), 7.26-
7.48 (m, 8H), 7.65 (m, 2H). 13C NMR (CDCl3): δ 21.1, 78.2,
127.1, 127.5, 128.2, 128.4, 128.5, 128.6, 129.4, 131.2, 133.8,
136.9, 169.5. IR (neat): 3030 w, 1743 s cm-1. MS (70 eV): m/z
(relative intensity, %) 288 (M+ + 2, 0.6), 286 (M+, 1.6), 244
(19), 191 (100), 77(100). HRMS Found: 286.0756. Calcd for
3-Ben zylid en e-2,5-d im et h yl-4-et h oxyca r b on yl-2,3-d i-
h yd r ofu r a n (16): white solid; mp 56-58 °C. Rf 0.23 (hexane/
1
ethyl acetate ) 10/1). H NMR (CDCl3): δ 0.67 (t, J ) 7.3 Hz,
3H), 1.53 (d, J ) 6.8 Hz, 3H), 2.23 (s, 3H), 3.62 (m, 2H), 5.27
(dq, J ) 2.7 Hz, J ) 6.8 Hz, 1H), 5.98 (d, J ) 2.7 Hz, 1H),
7.00-7.20 (m, 5H). 13C NMR (CDCl3): δ 13.2, 14.6, 21.8, 60.0,
84.4, 107.2, 112.8, 125.9, 127.7, 127.7, 138.9, 141.4, 165.5,
173.9. IR (KBr): 2984 bw, 1694 s, 1610 s cm-1. MS (70 eV):
m/z (relative intensity, %) 259 (M+ + 1, 6), 258 (M+, 31), 229
(11), 212 (100). Anal. Calcd for C16H18O3: C, 74.40; H, 7.02.
Found: C, 74.51; H, 7.04.
C
17H15O2Cl: 286.0761.
2-Acetoxy-3-ch lor o-1,1,1-tr ideu ter io-3-pen ten e (22). The
use of iodomethane-d3 instead of bromobenzene in the same
manner as described for 11 gave 22 in 77% yield (3.81 g, 23
mmol) from trans-2-chloro-2-butenal (3.13 g, 30 mmol) as a
1
colorless liquid, bp 90-92 °C/50 mmHg. H NMR (CDCl3): δ
4-Acet h yl-3-b en zylid en e-2,5-d im et h yl-2,3-d ih yd r ofu -
r a n (17): colorless liquid. Rf 0.29 (hexane/ethyl acetate ) 5/1).
1H NMR (CDCl3): δ 1.54 (s, 3H), 2.14 (s, 3H), 1.54 (d, J ) 6.5
Hz, 3H), 5.25 (dq, J ) 2.5 Hz, J ) 6.5 Hz, 1H), 6.02 (d, J ) 2.5
Hz, 1H), 7.10-7.30 (m, 5H). 13C NMR (CDCl3): δ 14.5, 21.7,
29.7, 84.2, 113.1, 116.9, 126.5, 127.8, 128.6, 138.7, 143.4, 171.7,
197.7. IR (neat): 2978 m, 2926 w, 1668 s cm-1. MS (70 eV):
m/z (relative intensity, %) 229 (M+ + 1, 16), 228 (M+, 100),
214 (11). HRMS Found: 228.1148. Calcd for C15H16O2: 228.1149.
Diet h yl 2-[3-(1-p h en yl-2-ch lor o)-1-b u t en yl]m a lon a t e
1.76 (d, J ) 6.5 Hz, 3H), 2.07 (s, 3H), 5.44 (bs, 1H), 5.91 (q, J
) 6.5 Hz, 1H). 13C NMR (CDCl3): δ 13.7, 17.9, 21.2, 72.6, 123.6,
134.1, 170.0. IR (neat): 2930 bm, 1739 bs, 1666 s cm-1. MS
(70 eV): m/z (relative intensity, %) 166 (M+ + 2, 0.2), 130 (68),
70 (100). HRMS Found: 165.0635. Calcd for C7H8O2D3Cl:
165.0636.
2-Ch lor o-1-(2,3,4,5,6-p en ta d eu ter io-p h en yl)-3-p h en yl-
2-p r op en yl Aceta te (23). The use of bromobenzene-d5 instead
of bromobenzene in the same manner as described for 12 gave
23 quantitatively (5.74 g, 23 mmol) from R-chlorocinnamal-
1
(18): yellow liquid. Rf 0.15 (hexane/ethyl acetate ) 10/1). H
NMR (CDCl3): δ 1.19 (t, J ) 7.1 Hz, 3H), 1.29 (t, J ) 7.1 Hz,
3H), 1.30 (d, J ) 6.8 Hz, 3H), 3.42 (dq, J ) 6.8 Hz, J ) 10.6
(14) Skattebøl, L. J . Org. Chem. 1966, 31, 1554.

Nucleophilic Substitution of the π-Allyl Ligand
J . Org. Chem., Vol. 64, No. 20, 1999 7527
Hz, 1H), 3.70 (d, J ) 10.6 Hz, 1H), 4.14 (q, J ) 7.1 Hz, 2H),
4.23 (q, J ) 7.1 Hz, 2H), 6.64 (s, 1H), 7.24-7.58 (m, 5H). 13C
NMR (CDCl3): δ 14.1, 17.2, 44.3, 56.1, 61.5, 61.6, 126.4, 127.8,
128.1, 129.1, 134.5, 135.2, 167.7, 168.8. IR (neat): 2984 m,
1737 bs cm-1. MS (70 eV): m/z (relative intensity, %) 324 (M+,
6), 289 (46), 129 (100). Anal. Calcd for C17H21O4Cl: C, 62.86;
H, 6.52; Cl, 10.92. Found: C, 62.74; H, 6.59; Cl, 10.96.
3-Ben zylid en e-4-et h oxyca r b on yl-5-m et h yl-2-p h en yl-
2,3-d ih yd r ofu r a n (19): colorless liquid. Rf 0.21 (hexane/ethyl
7.3 Hz, J ) 2.7 Hz, 1.5H, CH3/CD3 ) 1/1), 2.20 (s, 3H, CH3),
4.25 (q, J ) 7.3 Hz, 2H, CH2), 4.91-4.97 (m, 1H, CH), 4.99-
5.07 (m, 1H, 2-H). 13C NMR (CDCl3): δ 14.3 (CH3), 14.6 (CH3/
CD3 ) 1/1), 15.2 (CH3), 21.9 (CH3/CD3 ) 1/1), 59.9 (CH2), 83.6,
83.7 (2-C), 106.6 (4-C), 109.0, 109.1 (CH), 139.6 (5-C), 165.6
(CO), 172.5 (3-C). IR (neat): 2982 bm, 1711 s, 1619 s cm-1
.
MS (70 eV): m/z (relative intensity, %) 200 (M+ + 1, 13), 199
(M+, 100), 171 (13). HRMS Found: 199.1289. Calcd for
C
11H13O3D3: 199.1288.
1
acetate ) 10/1). H NMR (CDCl3): δ 0.68 (t, J ) 7.0 Hz, 3H),
3-Ben zylid en e-4-et h oxyca r b on yl-5-m et h yl-2-p h en yl-
2.31 (s, 3H), 3.66 (m, 2H), 5.87 (d, J ) 2.4 Hz, 1H), 6.10 (d, J
) 2.4 Hz, 1H), 7.05-7.25 (m, 5H), 7.40 (m, 5H). 13C NMR
(CDCl3): δ 13.2, 14.5, 60.2, 89.7, 107.9, 116.2, 126.1, 127.6,
127.7, 128.8, 128.9, 138.7, 139.4, 140.0, 165.2, 173.9. IR
(neat): 2982 bm, 1705 s, 1610 s cm-1. MS (70 eV): m/z (relative
intensity, %) 321 (M+ + 1, 75), 320 (M+, 59), 275 (41), 204 (100),
77 (23). HRMS Found: 320.1421. Calcd for C21H20O3: 320.1411.
4-Acet h yl-3-b en zylid en e-5-m et h yl-2-p h en yl-2,3-d ih y-
d r ofu r a n (20): white solid. Rf 0.14 (hexane/ethyl acetate )
2,3-d ih yd r ofu r a n (25): colorless liquid. Rf 0.21 (hexane/ethyl
1
acetate ) 10/1). H NMR (CDCl3): δ 0.68 (t, J ) 7.0 Hz, 3H,
CH3), 2.31 (s, 3H, CH3), 3.66 (m, 2H, CH2), 5.87 (d, J ) 2.4
Hz, 1H, CH), 6.10 (d, J ) 2.4 Hz, 1H, 2-H), 7.05-7.25 (m, 2.5H,
Ph/Ph-d5 ) 1/1), 7.40 (m, 2.5H, Ph/Ph-d5 ) 1/1).
Rea ction w ith P t(d ba )2 a n d Ap p r op r ia te Liga n d a s
Ca ta lyst. PPh3 (26.2 mg, 0.1 mmol) was added to a suspension
of Pt(dba)2 (33.2 mg, 0.05 mmol) in THF (1 mL). The mixture
was stirred at room temperature for 30 min. To this solution
was added 2-chloro-allyl acetate 1 (67.5 mg, 0.5 mmol). Sodium
ethyl acetoacetate [generated from ethyl acetoacetate (130 mg,
1.0 mmol) and NaH (60 wt % in mineral oil, 40 mg, 1.0 mmol)
in THF (4 mL) at 0 °C] was slowly added, and the flask was
then immersed in an oil bath at 80 °C. The reaction was
monitored by analytical GC, and after 2 h the substrate had
been completely consumed. Yields were determined by GC with
n-pentadecane as an internal standard.
1
10/1). H NMR (CDCl3): δ 1.58 (s, 3H), 2.22 (s, 3H), 6.08 (d, J
) 2.7 Hz, 1H), 5.93 (d, J ) 2.7 Hz 1H), 7.10-7.40 (m, 10H).
13C NMR (CDCl3): δ 14.4, 29.7, 89.4, 116.3, 117.4, 126.7, 127.3,
127.7, 128.5, 128.8, 128.9, 138.4, 139.3, 141.9, 171.7, 197.3.
Diet h yl 2-[1-(1,3-Dip h en yl-2-ch lor o)-2-p r op en yl]m a -
lon a te (21): yellow liquid. Rf 0.11 (hexane/ethyl acetate ) 10/
1
1). H NMR (CDCl3): δ 1.00 (t, J ) 7.1 Hz, 3H), 1.23 (t, J )
7.1 Hz, 3H), 3.98 (q, J ) 7.1 Hz, 2H), 4.21 (q, J ) 7.1 Hz, 2H),
4.57 (d, J ) 6.0 Hz, 1H), 4.36 (d, J ) 6.0 Hz, 1H), 6.81 (s, 1H),
7.25-7.57 (m, 10H). 13C NMR (CDCl3): δ 13.7, 14.1, 54.9, 55.0,
61.6, 61.9, 126.6, 127.7, 127.9, 128.1, 128.4, 129.2, 133.4, 134.4,
137.7, 166.9, 167.4. IR (neat): 2984 bm, 1736 bs cm-1. MS (70
eV): m/z (relative intensity, %) 388 (M+ + 2, 1), 387 (M+ + 1,
1), 386 (M+, 3), 351 (24), 277 (100). Anal. Calcd for C22H23O4-
Cl: C, 68.30; H, 5.99; Cl, 9.16. Found: C, 68.29; H, 6.16; Cl,
9.06.
Ack n ow led gm en t. This work was supported, in
part, by grants from Monbusho. Thanks are given to
the Instrumental Analysis Center, Faculty of Engineer-
ing, Osaka University, for assistance in obtaining
HRMS and elemental analyses.
Su p p or tin g In for m a tion Ava ila ble: The detailed ex-
perimental procedures and spectral data. This material is
available free of charge via the Internet at http://pubs.acs.org.
3-Met h ylid en e-2,5-d im et h yl-4-et h oxyca r b on yl-2,3-d i-
h yd r ofu r a n (24): colorless liquid. Rf 0.28 (hexane/ethyl
1
acetate ) 10/1). H NMR (CDCl3): δ 1.34 (t, J ) 7.3 Hz, 3H,
CH3), 1.38 (d, J ) 6.5 Hz, 1.5H, CH3/CD3 ) 1/1), 1.76 (dd, J )
J O990845X