Chemistry Letters 2002
439
Scheme 4.
Table 2. Reaction of 1 with TMSOTf8
2
Conditions
R0 Time/h Base/equiv
Product (Yield/%)
3
R
2a
2a
Ph
Ph
H
H
6
6
6
6
6
2
3
3
3
3
3a
3a
3b
3c
3d
36
82
90
86
73
2b p-Tol Me
2c p-ClC6H4 Cl
2d
Me
H
Scheme 6.
lower yields.
Winterman, J. Chem. Soc., Chem. Commun., 1968, 723. For a
review, see N. Campbell, ‘‘Rodd’s Chemistry of Carbon
Compounds,’’ ed. by S. Coffey, Elzsevier, Amsterdam
(1978), Vol. IIIg, Chap. 27.
R. P. Linstead and S. L. S. Thomas, J. Chem. Soc., 1940, 1127;
H. M. Liu, B. L. Tian, and Y. D. Xu, Appl. Catal., A, 213, 103
(2001); A. T. Mathauser and A. V. Teplyakov, Catal. Lett., 73,
207 (2001).
During the investigation on lignan group, Haworth and
Atkinson reported the synthesis of 6,7-dimethoxy-1,3-dimethyl-
naphthalene (3e) via six-step reactions from veratrylacetyl
chloride.9 We then applied the present method to the synthesis
of 3e starting from 3,4-dimethoxyacetophenone. As shown in
Scheme 5, naphthalene 3e was synthesized regiospecifically.
2
3
4
T. T. Hoye, M. Chen, B. Hoang, L. Mi, and O. P. Priest, J. Org.
Chem., 64, 7184 (1999).
M. P. Sibi, J. W. Dankwardt, and V. Snieckus, J. Org. Chem.,
51, 271 (1986).
5
6
F. M. Beringer and S. J. Huang, J. Org. Chem., 29, 445 (1964).
K. Okuma, S. Hayano, K. Shioji, and H. Matsuyama,
Tetrahedron Lett., 41, 2171 (2000).
7
8
P. G. Gassman, S. J. Burns, and K. B. Pfister, J. Org. Chem.,
58, 1449 (1993).
Satisfactory mass spectra and/or elemental analyses were
obtained for all new compounds. Selected 1H NMR data of 2b
and 3c. 2b: 1H NMR (CDCl3) ꢂ ¼ 2:29 (s, 6 H, ArMe), 3.22
(br s, 2 H, CH2), 4.43 (br s, 2H, CH2), 4.83 (br s, 1 H, ¼ CHH),
4.99 (br s, 1 H, ¼ CHH), 7.09 (d, 4 H, J ¼ 8 Hz, p-Tol), 7.29
(d, 4 H, J ¼ 8 Hz, p-Tol). 3c: 1H NMR (CDCl3) ꢂ ¼ 2:53 (s, 3
H, ArMe), 7.22 (br s, 1 H, Ar), 7.29 (dd, 1 H, J ¼ 2 and 8 Hz,
Ar), 7.38 (d, 2 H, J ¼ 8 Hz, p-ClC6H4-), 7.45 (d, 2 H,
J ¼ 8 Hz, p-ClC6H4-), 7.54 (s, 1 H, Ar), 7.70 (d, 1 H,
J ¼ 8 Hz, Ar), 7.79 (s, 1 H, Ar). 3e: 1H NMR (CDCl3)
ꢂ ¼ 2:43 (Me), 2.60 (Me), 3.99 (OMe), 4.01 (OMe), 7.04 (br
s, Ar-H), 7.06 (br s, Ar), 7.16 (br s, Ar), 7.34 (br s, Ar).
R. D. Haworth and J. R. Atkinson, J. Chem. Soc., 1938, 767.
Scheme 5.
A tentative mechanistic rationalization for the observed
novel benzoannelation involves the initial attack of 1 with
TMSOTf. The oxonium ion intermediate (9) thus formed was
further attacked by a base to give diene (10). Rearrangement of 10
followed by proton abstraction gave an exomethylene compound
(11), which finally produced naphthalene, 3 (Scheme 6).
We are currently continuing further investigation on the
reaction and synthetic application of these compounds.
9
References and Notes
1
R. W. Alde, P. S. Bowman, W. R. Steele, and D. R.