Synthesis of 1-stibaphenalenes, the first example of group 15 phenalenes, via a 1,5-dilithium intermediate

Article abstract of DOI:10.1246/cl.2001.554

The first examples of 1-stibaphenalenes 1 and 6 have been prepared by the condensation of dibromophenylstibane with 1,5-dilithium intermediate 5, generated in situ from (Z)-1-bromo-2-[1-(8-bromonaphthyl)]-1-trimethylsilylethene (4). Single crystal X-ray a

Full text of DOI:10.1246/cl.2001.554

554
Chemistry Letters 2001
Synthesis of 1-Stibaphenalenes, the First Example of Group 15 Phenalenes,
via a 1, 5-Dilithium Intermediate
Shuji Yasuike, Mayumi Niwa, Kentaro Yamaguchi,† Takashi Tsuchiya, and Jyoji Kurita*
Faculty of Pharmaceutical Sciences, Hokuriku University, Kanagawa-machi, Kanazawa 920-1181
†Chemical Analysis Center, Chiba University, Inage-ku, Chiba 263-8322
(Received March 12, 2001; CL-010215)
The first examples of 1-stibaphenalenes 1 and 6 have been
bromo compound, (Z)-1-bromo-2-(1-naphthyl)-1-trimethylsi-
prepared by the condensation of dibromophenylstibane with
1,5-dilithium intermediate 5, generated in situ from (Z)-1-
bromo-2-[1-(8-bromonaphthyl)]-1-trimethylsilylethene (4).
Single crystal X-ray analysis of 1 revealed that the naphthalene
and the fused stibinine ring are almost coplanar (mean deviation
0.0264 Å), and the phenyl group on the antimony is oriented
perpendicular with the phenalene ring.
lylethene, prepared from 1-iodonaphthalene by the same proce-
dure, was used instead of the dibromo compound 4 in the above
reaction, no ring-closure products were formed. This result
indicates that the presence of the bromine moiety in the 8 posi-
tion on the naphthalene ring is essential for the formation of
1,5-dilithium intermediate 5 under the present conditions. The
TMS group in 6 was readily removed by treatment with TBAF
in THF containing water to give the desired C-unsubstituted 1-
phenalene 1 in 61% yield.9 The stibaphenalenes 6 and 1
obtained here were isolated as stable crystalline compounds,
and no change was observed even when heated at 110 °C for 24
h in toluene in the presence or in the absence of AIBN.
Treatment of stibaphenalene 1 with SO2Cl2 resulted in oxida-
tion of antimony atom to afford 1,1-dichloro-1-phenyl-λ5-
stibaphenalene (mp 224–228 °C), which reverted to 1 by treat-
ment with aqueous Na2S.
The synthesis of new heterocyclic rings containing main
group heavier elements other than nitrogen, oxygen or sulfur
has recently received increasingly intensive study, and a variety
of monocyclic and fused heterocyclic compounds containing
group 14 (Si, Ge, and Sn), group 15 (P, As, and Sb), and group
16 (S, Se, and Te) heavier elements have been prepared.1 With
regards to 1-heterophenalenes, however, only a few examples
such as 1-silaphenalenes2 and 1-thiaphenalene3 have been
reported. On the other hand, we have recently reported that the
condensation of 1,4-, 1,6- and 1,9-dilithium compounds, gener-
ated from the appropriate dihalides by treatment with alkyllithi-
um reagents, with group 14, 15, and 16 dihalides (MX2,
M=SiR2, GeR2, SnR2, AsR, SbR, BiR, Se, and Te), afforded the
corresponding hetroles,4 heteroepines,5 and heteroecines,6
respectively. In the course of our continuing studies on the syn-
thesis of new heterocyclic compounds, we were interested in
the synthesis of new 1-heterophenalens. Here we report the
synthesis of 1-stibaphenalenes which are the novel hertero-
cyclic ring systems, by the condensation of dibromophenyl-
stibane with the key 1,5-dilithium intermediate 5, and the X-ray
crystal structure of C-unsubstituted 1-stibaphenalene 1 obtained
from the desilylation of 6 with TBAF.
The present synthetic routes to 1-stibaphenalenes 6 and 1
are shown in Scheme 1. 1-Bromo-8-iodonaphthalene (2),7 pre-
pared from 1,8-naphthalic anhydride via 3 steps, was coupled
with trimethylsilylacetylene in diethylamine in the presence of
a catalytic amount of a mixture of bis(triphenylphosphine)palla-
dium dichloride and copper(I) iodide to afford 1-[(8-bromo-
naphthyl)]-2-trimethylsilylacetylene (3) in 69% yield.8 The
alkyne 3 was hydraluminated with DIBAL-H followed by
bromination with NBS, giving rise to the (Z)-1-bromo-2-[1-(8-
bromonaphthyl)]-1-trimethylsilylethene (4) in 59% yield. The
stereochemistry of the olefine function on 4 was elucidated by
1H NMR spectral analysis; an NOE was observed between 2-H
and the TMS protons, indicating that the C1–C2 bond has
(Z)–stereochemistry. The dibromo compound 4 was treated
with a large excess (5–6 mol equiv) of tert-butyllithium in dry
ether under an argon atmosphere at –80 °C, and followed with
dibromophenylstibane, resulting in ring closure to form the
expected 2-trimethylsilyl-1-stibaphenalene 6. When a mono-
The structures of 1-stibaphenalenes 6 and 1 were elucidat-
ed mainly by their HRMS, NMR spectral and combustion
1
analyses. In the H NMR spectrum of 6, the signals for TMS
protons and 2-H appeared at δ 0.15 (s) and δ 7.76 (s), respec-
tively, while in 1, two vinyl protons appeared at δ 6.79 for 2-H
and δ 7.36 for 3-H (each d, J=12.8 Hz).
The ORTEP drawing (a) and its side view (b) of the C-
unsubstituted 1-stibaphenalene 1 obtained from the single crystal
X-ray analysis are illustrated in Figure 1.10 The results revealed
that the naphthalene and the fused stibinine rings are almost pla-
nar (mean deviation 0.0264 Å) to each other. The phenyl group
Copyright © 2001 The Chemical Society of Japan

Chemistry Letters 2001
555
on the antimony atom is oriented nearly perpendicular to the
phenalene ring; the dihedral angles for C(3)–C(2)–Sb–C(1'),
C(9)–C(9a)–Sb–C(1'), and C(9b)–C(9a)–Sb–C(1') are –98.3(10)°,
–82.1(8)°, and 100.1(7)°, respectively. The three Sb–C distances,
Sb–C(2) (2.125 Å), Sb–C(9a) (2.174 Å), and Sb–C(1') (2.135 Å),
are close to the typical range of Sb–C (sp2) bonds (2.1–2.25
Å),5b,11 and no noticeable difference in the C–C bond lengths is
seen, except for the C(1)–C(2) bond (1.30 Å) which is relatively
shorter than that of a standard double bond. The bond angles sur-
rounding of the antimony atom are slightly undistributed (91.6°,
95.4°, and 98.4°), in that the inner angle of the stibinine ring
(C2)–Sb–C(9a) (91.6°) is increased owing to an influence of the
ring closing to a 6-membered ring; the corresponding angles for 5-
membered 4,7-dimethoxy-2,3-dimethyl-1-phenylstibindole11 and
7-membered 1-phenyl-1-benzostibepine5b have been reported to
be 79.9° and 85.8°, respectively.
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3
4
5
a) S. Yasuike, H. Ohta, S. Shiratori, J. Kurita, and T.
Tsuchiya, J. Chem. Soc., Chem. Commun., 1993, 1817; b)
S. Yasuike, S. Shiratori, J. Kurita, and T. Tsuchiya, Chem.
Pharm. Bull., 47, 1108 (1999).
6
7
8
9
S. Yasuike, S. Tsukada, J. Kurita, T. Tsuchiya, Y. Tsuda,
H. Kiuchi, and S. Hosoi, Heterocycles, 53, 525 (2000).
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42, 1480 (1977).
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Hagihara, Synthesis, 1980, 627.
Satisfactory analytical (combustion and/or high-resolution
mass) and spectral (IR, NMR, and MS) data were obtained
for all new compounds reported. 3: yellow oil; 4: pale yel-
1
low oil; 6: mp 129–130 °C, pale red prisms (hexane), H
NMR (400 MHz, J Hz, CDCl3, Std., CH2Cl2, δ 5.30); δ
0.15 (9Η, s, TMS), 7.1–7.2 (3H, m, Ar-H), 7.36 (1H, dd, J
= 8.2 and 7.2, Ar-H), 7.4–7.5 (4H, m, Ar-H), δ 7.76 (1H, s,
3-H), δ 7.78 (1H, dd, J = 5.1 and 1.5, Ar-H), 7.8–7.85 (2H,
m, Ar-H); HR-MS; m/z: 422.0458 (Calcd. for C21H21SbSi,
422.0451); 1: mp 77–78 °C, colorless needles (MeOH), 1H
NMR (400 MHz, J Hz, CDCl3, Std., CH2Cl2, δ 5.30); δ
6.79 (1H, d, J = 12.8, 2-H), 7.15–7.2 (3H, m, Ar-H), 7.39
(1H, dd, J = 8.5 and 7.0, Ar-H), 7.4–7.5 (4H, m, Ar-H),
7.56 (1H, d, J = 12.8, 3-H), 7.75–7.85 (3H, m, Ar-H); UV
λmax nm(log ε) (EtOH) 228(4.32), 235(4.32), 267sh (3.75),
319sh (3.81), 325sh (3.88), 336(4.00), 341sh (3.99), 325
(3.96); HR-MS; m/z: 350.0054 (calcd for C18H13Sb,
350.0055).
It is clear from the above results that the condensation of
1,5-dilithium intermediate 5, readily accessible from 1-bromo-
8-iodonaphthalene, with the dibromostibane gave the novel ring
system 1-stibaphenalene 6 which can be easily derived to the C-
unsubstituted 1-stibaphenalenes 1. To the best of our knowl-
edge, these are the first examples of 1-heterophenalens having
group 15 heavier elements. Further studies in this area, includ-
ing the chemical behavior of 1-stibaphenalenes and the prepara-
tion of 1-heterophenalenes comprising other heavier elements,
are in progress.
Partial financial support for this work was provided by a
Grant-in Aid for Scientific Research (No. 09672172) from the
Ministry of Education, Science, Sports and Culture of Japan.
10 Crystal data for 1: C18H13Sb, fw =351.05, monoclinic, a =
11.043(3), b = 5.330(6), c = 23.22(2) Å, β = 98.68 (6)°, V =
1350(1) Å3, T = 100±1 K, space group P21/c(no. 14), Z = 4,
µ(Mo Kα ) = 20.21 cm–1, 1948 reflections measured, 1776
reflections {I>2.40 σ(I)} were used in all calculations, R =
0.068, Rw = 0.092. The data were collected on a Rigaku
RAXIS-II imaging plate area detector with graphite-mono-
chromated Mo Kα (λ = 0.71070 Å). All of the structures
were solved by direct method (program SIR92) and expand-
ed using Fourier technique (program DIRDIF94)
References and Notes
1
“Comprehensive Heterocyclic Chemistry,” ed. by A. R.
Katritzky and C. W. Rees, Pergamon Press, Oxford (1984);
“Comprehensive Heterocyclic Chemistry II,” ed. by A. R.
Katritzky, C. W. Rees, and E. F. V. Scriven, Pergamon
Press, Oxford (1995).
2
E. A. Chernyshev and S. A. Schepinov, J. Gen. Chem.
USSR, 49, 1732 (1970); I. G. Makassov, V. M. Kazakova,
L. N. Shamsin, N. G. Komalenkova, and E. A.
11 S. Buchwald, R. A. Fisher, and B. M. Foxman, Angew.
Chem., Int. Ed. Engl., 29, 771 (1990).