6
476
J . Org. Chem. 1996, 61, 6476-6477
Communications
Ta ble 1. Rea ction of 1-Na p h th ol (1a ) w ith Aceta ld eh yd e
Syn th esis of Na p h th ofu r a n -2(3H)-on e
Der iva tives by P a lla d iu m -Ca ta lyzed
Th r ee-Com p on en t Cou p lin g Usin g
Na p h th ols, Ald eh yd es, a n d Ca r bon
Mon oxid e
(
2a ) u n d er Ca r bon Mon oxid ea
Tetsuya Satoh, Takatoshi Tsuda, Yuichi Kushino,
Masahiro Miura,* and Masakatsu Nomura
yield of
yield of
3a (%)
b
Department of Applied Chemistry, Faculty of Engineering,
Osaka University, Suita, Osaka 565, J apan
entry
acid
3a (%)b entry
acid
1
2
3
none
CF3COOH
32
97
28
4
C6H5COOH
TsOH
CF COOH
26
54
∼100
5
Received J une 10, 1996
CH COOH
6c
3
3
a
Reaction conditions: 1a (2 mmol), 2a (6 mmol), Pd(PPh3)4 (0.05
Benzofuranone and isobenzofuranone nuclei are found
in various naturally occurring compounds, and a number
of their natural and synthetic derivatives are known to
mmol), and acid (0.05 mmol) in C6H6 (5 mL) under CO (5 atm) at
1
was used.
20 °C for 18 h. b Determined by GLC analysis. c 2a (10 mmol)
1
exhibit interesting biological properties. Thus, new,
3
in Table 1). Addition of CF COOH (0.05 mmol) as
cocatalyst was found to remarkably enhance the yield of
effective synthetic routes to them are of considerable
interest. Meanwhile, transition metal-catalyzed carbo-
nylation may be one of the most useful strategies for the
synthesis of lactones, and indeed, various methods to
construct them, including benzofuranones, have been de-
3
a (97%) (entry 2). Other acids such as CH
3
COOH, C
6
H
5
-
-
COOH, and TsOH, however, were not as effective as CF
3
COOH (entries 3-5). Furanone 3a was almost quanti-
tatively produced, when the amount of 2a was increased
to 10 mmol in the presence of CF COOH (entry 6).
3
Table 2 summarizes the results for the reactions of 1a
with aldehydes 2b-d (1-2.5 equiv) and of 1b-d with
2
veloped; they usually involve intramolecular carbonyl-
ative cyclization of halo alcohols or unsaturated alcohols.
In the context of our study of synthesis of heterocyclic
3
compounds by means of homogeneous catalysis, we have
2
a (5 equiv) using Pd(PPh
3
)
4
or a combination of Pd(OAc)
COOH. It can be seen
2
found that naphthofuran-2(3H)-one analogues can be
efficiently produced by three-component tandem reaction
using 1- or 2-naphthols, aldehydes, and carbon monoxide
in the presence of a palladium catalyst (eq 1).
and PPh in the presence of CF
3
3
that 3-alkyl- and 3-arylnaphthofuran-2(3H)-ones 3b-g
could be produced in fair to good yields.4 Note that
naphtho[2,1-b]furan-2(3H)-ones 3f and 3g were exclu-
sively formed in the reaction using 2-naphthols 1c and
1
d as substrates, no [2,3-b] isomers being detected. In
contrast to the high reactivity of naphthols, treatment
of phenol or 4-methoxyphenol with 2a or 2b gave no
expected coupling product.
The present three-component reaction may involve the
initial nucleophilic addition of naphthol 1 to aldehyde 2,
3
which may be promoted by CF COOH, to give dihydroxy
intermediate I,5 followed by carbonylation under the
influence of palladium species used, as depicted in
Scheme 1 with 1a as the representative. The inertness
of phenols for this reaction seems to be attributable to
the difficulty of the corresponding first step, i.e., nucleo-
philic addition of phenols to 2 under the conditions
employed. Actually, it was confirmed that benzofura-
nones 5a and 5b could be obtained, when 2-hydroxyben-
zyl alcohols 4a and 4b were treated under similar
reaction conditions (eq 2). In these reactions, addition
of appropriate acids also increased the lactone yield. On
the other hand, treatment of 1-(2-naphthyl)ethanol (6)
,6
When a mixture of 1-naphthol (1a ) (2 mmol) and
acetaldehyde (2a ) (6 mmol) was heated in the presence
of Pd(PPh
atm) at 120 °C for 18 h, 3-methylnaphtho[1,2-b]furan-
(3H)-one (3a ) was produced in a yield of 32% (entry 1
3 4 6 6
) (0.05 mmol) in C H (5 mL) under CO (5
2
(1) (a) Anacardio, R.; Arcadi, A.; D’Anniballe, G.; Marinelli, F.
Synthesis 1995, 831 and references therein. (b) Ramachandran, P. V.;
Chen, G.-M.; Brown, H. C. Tetrahedron Lett. 1996, 37, 2205 and
references therein.
(4) In the reaction with 2b, a small amount of aldol type dimeriza-
tion product (<10%) of the aldehyde was detected by GC-MS, suggest-
ing that the side reaction is not significant.
(2) (a) Bahrmann, H.; Cornils, B.; Frohning, C. D.; Mullen, A. New
Syntheses with Carbon Monoxide; Falbe, J ., Ed.; Springer-Verlag: New
York, 1980. (b) Comprehensive Organometallic Chemistry; Wilkinson,
G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon: Oxford, 1982; Vol. 8.
(5) Such a reaction of phenolic compounds with aldehydes is well-
known to be catalyzed by acidic species including carboxylic acids,
e.g.: (a) Martini, J . C.; Franke, N. W.; Singerman, G. M. J . Org. Chem.
1970, 35, 2904. (b) Nagata, W.; Okada, K.; Aoki, T. Synthesis 1979,
365.
(
c) Colquhoun, H. M.; Holton, J .; Thompson, D. J .; Twigg, M. V. New
Pathways for Organic Synthesis; Plenum: New York, 1984. (d)
Coloquhoun, H. M.; Thompson, D. J .; Twigg, M. V. Carbonylation;
Plenum: New York, 1991.
(6) It has been confirmed by 1H NMR that a part of Pd(PPh
)
is
transformed into hydridopalladium species in the presence of an
equimolar amount of CF COOH in benzene-d at room temperature:
Kushino, Y.; Itoh, K.; Miura, M.; Nomura, M. J . Mol. Catal. 1994, 89,
3
4
(
3) (a) Okuro, K.; Furuune, M.; Miura, M.; Nomura, M. J . Org.
3
6
Chem. 1993, 58, 7606. (b) Miura, M.; Enna, M.; Okuro, K.; Nomura,
M. J . Org. Chem. 1995, 60, 4999. (c) Satoh, T.; Itaya, T.; Okuro, K.;
Miura, M.; Nomura, M. J . Org. Chem. 1995, 60, 7267.
151. Thus, Pd(II) species such as (PPh
catalyze the initial reaction.
3 2 2 3
) Pd(H)(O CCF ) could also
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