C. D. Gabbutt et al. / Tetrahedron Letters 45 (2004) 6151–6154
6153
ritzky, A. R., Rees, C. W., Scriven, E. F. V., Eds.;
Pergamon: Oxford, 1996; p 349.
2. (a) Clarke, D. A.; Heron, B. M.; Gabbutt, C. D.;
Hepworth, J. D.; Partington, S. M.; Corns, S. N. PCT
WO 00/18755, 2000; (b) Chan, Y.-P.; Breyne, O.; Jean, P.
PCT WO 01/36424, 2001; (c) Nelson, C. M.; Chopra, A.;
Petrovskaia, O. G.; Van Gemert, B.; Kumar, A. PCT WO
01/19813, 2001; (d) Mann, C.; Melzig, M.; Weigand, U.
PCT WO 03/080595, 2003; (e) Izumi, S.; Nagoh, H.; PCT
WO 03/042203, 2003.
3. (a) Bouas-Laurent, H.; Durr, H. Pure Appl. Chem. 2001,
73, 639; (b) Kobatake, S.; Irie, M. Ann. Rep. Prog. Chem.,
Sect. C 2003, 99, 277; (c) Organic Photochromic and
Thermochromic Compounds, Main Photochromic Families;
Crano, J. C., Guglielmetti, R. J., Eds.; Plenum: New York,
1999; Vol. 1.
4. (a) Gabbutt, C. D.; Heron, B. M.; Instone, A. C.; Thomas,
D. A.; Partington, S. M.; Hursthouse, M. B.; Gelbrich, T.
Eur. J. Org. Chem. 2003, 1220; (b) Gabbutt, C. D.; Heron,
B. M.; Instone, A. C. Heterocycles 2003, 60, 843; (c)
Gabbutt, C. D.; Gelbrich, T.; Hepworth, J. D.; Heron, B.
M.; Hursthouse, M. B.; Partington, S. M. Dyes Pigments
2002, 54, 79.
5. Carbenes and carbenoids display a rich and varied
chemistry and have featured in severalreview articels:
(a) Doyle, M. P.; McKervey, M. A.; Ye, T. Modern
Catalytic Methods for Organic Synthesis with Diazo
Compounds from Cyclopropanes to Ylides; Wiley Inter-
science: New York, 1998; (b) Doyle, M. P.; Forbes, D. C.
Chem. Rev. 1998, 98, 911; (c) Doyle, M. P. Chem. Rev.
1986, 86, 919; (d) Merlic, C. A.; Zechman, A. L. Synthesis
2003, 1137.
6. Ethyl3,3-bis(4-methoxypheny)-l3 H-naphtho[1,2-b]pyran-
8-ylacetate, 4, mp 164–165 °C. Selected 1H NMR data:
ethoxy group d 4.14 (2H, q, J 7.1, OCH2), d 1.23 (3H, t,
J 7.1, CH2CH3), methylene unit d 3.71 (2H, s, CH2CO2Et)
and the AB system for the pyran ring protons d 7.26
(1H, d, J 9.9, 1-H) and d 6.20, (1H, d, J 9.9, 2-H). HRMS
gave m/e 481.2018 for [MþH]þ corresponding to
C31H28O5 with a characteristic fragmentation involving
loss of a geminal 4-methoxyphenyl function to give a base
peak m/e 373.
Figure 2. X-ray crystalstructure of 11.
nyl)prop-20-enyl]-3-hydroxymethyl-7-methoxy-1-naph-
thol 9 was obtained by column chromatography in 55%
yield. Evidently under the more forceful reaction con-
ditions ring opening of the pyran unit ensues and
reduction of the quinone methide unit is effected.
Diazoacetylation of the hydroxymethyl function of 8
was readily accomplished to afford 10 in 45% yield using
ethyl 2-diazomalonyl chloride according to the proce-
dure reported by Padwa and co-workers.12 Treatment of
a solution of this tethered carbenoid precursor with
Rh2(OAc)4 in CH2Cl2 at rt resulted in the formation of
the tetracycle 1113 in 92% yield together with a small
amount of the oxidation product, the aldehyde 12 (d
10.08, CHO; [MþH]þ, 453.1706). The structure of 12
was confirmed by unambiguous synthesis from 8 using
Swern methodology.14 An X-ray crystalstructure of 11
is presented in Figure 2.15 The intramolecular cycload-
dition of the tethered Rh-carbenoid derived from
(1-naphthylmethyl) diazoacetate to the 1,2-bond of the
naphthalene moiety gives a tetracyclic unit structurally
related to 11.16
7. Friebolin, H. Basic One- and Two-Dimensional NMR
Spectroscopy; VCH: Weinheim, 1991; p 81.
8. Gabbutt, C. D.; Hepworth, J. D.; Heron, B. M.;
Partington, S. M.; Thomas, D. A. Dyes Pigments 2001,
49, 65.
Further reactions of carbenes and carbenoids with
photochromic naphthopyrans will be reported in due
course.
9. Crystaldata for 6: C31H28O5, M ¼ 480:53, monoclinic,
space group P21/n, a ¼ 11:2735ð2Þ, b ¼ 7:98560ð10Þ,
3
ꢀ
ꢀ
c ¼ 27:8570ð5Þ A, b ¼ 99:050ð3Þ, U ¼ 2476:63ð7Þ A ,
Dcalcd ¼ 1:289 Mg mÀ3
,
Z ¼ 4, Mo Ka radiation (k ¼
0:71073 A), l ¼ 0:087 mmÀ1
,
T ¼ 120ð2Þ K, 13427
ꢀ
Acknowledgements
measured
reflections,
3497
observed reflections
(Rint ¼0:3539), R1 ¼ 0:2823 ½F 2 > 2rðF 2Þꢀ, wR2 ¼ 0:3563
(all data). The structure was solved and refined using
the SHELXL-97 suite of programs.17 Crystallographic
data (excluding structure factors) for this structure have
been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication no CCDC
223219.
We thank the EPSRC and James Robinson Ltd,
(Huddersfield) for an industrial CASE award to DAT
and the EPSRC for access to the X-ray crystallography
service (University of Southampton) and for access to
the HRMS service (University of Swansea).
10. Gabbutt, C. D.; Hepworth, J. D.; Heron, B. M.; Thomas,
D. A.; Kilner, C.; Partington, S. M. Heterocycles 2004, 63,
567.
References and notes
11. The cycloaddition of rhodium carbenoids to the pyran
ring double bond in benzopyrans to afford cyclo-
propa[c]benzopyrans has been described, for example,
Blanchard, L. A.; Schneider, J. A. J. Org. Chem. 1986, 51,
1. (a) Kuthan, J. Adv. Heterocycl. Chem. 1983, 34, 145; (b)
Kuthan, J.; Sebek, P.; Boehm, S. Adv. Heterocycl. Chem.
1995, 62, 19; (c) Hepworth, J. D.; Gabbutt, C. D.; Heron,
B. M. In Comprehensive Heterocyclic Chemistry II; Kat-
€
1372; Lindstrom, S.; Sahlberg, C.; Kalyanov, G.; Oden,
L.; Naeslund, L. PCT WO 02/070516, 2002.
ꢁ