C O M M U N I C A T I O N S
Table 1. Selected Bonding Distances in Iodine(III) Compounds 3-7
compound
bond a (Å)
bond b (Å)
bond c (Å)
bond d (Å)
bond e (Å)
bond f (Å)
3a
1.227(4)
1.313(15)
1.276(13)
1.223(4)
1.24(2)
1.256(5)
1.226(14)
1.221(13)
1.272(4)
1.28(2)
2.484(2)
2.605(8)
2.569(8)
2.478(4)
2.34(1)
3.270(2)
3.097(3)
3.096(3)
2.056(3)
2.061(12)
2.060(10)
2.105(4)
2.03(2)
1.736(3)
1.744(11)
1.756(11)
3b (molecule 1)
3b (molecule 2)
4 (ref 5a)
5 (ref 5b)
2.77(1)
6 (ref 6a)
7 (ref 9)
2.053(13)
2.454(1)
1.710(13)
1.220(5)
1.321(5)
2.145(3)
2.943(1)
difference is smaller for the other molecule, but still significant.
The interatomic distance between O(22′)-O(12) (2.491 Å) is
consistent with intermolecular hydrogen bonding of a carboxylate
with a carbonyl of the neighboring molecule. Although the position
of the hydrogen was not detected in the diffraction analysis, the
long C(10)-O(12) bond length supports the presence of the
carboxylate as depicted (Figure 1). It should be noted that in
comparison to molecules 3a, 4, and 5, molecule 3b displays an
inverse relationship between the exocyclic and endocyclic I-O bond
lengths, that is, a longer I-O bond within the iodoxole ring of 3b.
This is expected due to a reduced basicity of this oxygen resulting
from coordination of the other oxygen to hydrogen. Overall, the
solid-state arrangement of 3b is ordered into infinite zigzagging
chains via a combination of hydrogen bonding and secondary
bonding interactions.
Preliminary experiments have demonstrated that the chemical
properties of compounds 3 are quite different from those of the
noncyclic phosphoranyl derivatives 6 and other known iodonium
salts. In contrast to the noncyclic derivatives 6,6b benziodoxoles 3
are not reactive toward soft nucleophiles, such as PhS- and I-
anions, even at elevated temperature (up to 100 °C) and in the
presence of copper or palladium catalysts. On the other hand,
compounds 3 readily react with strong acids (e.g., HOTf), affording
phosponium salts 8 and benziodoxole 9 as major products (Scheme
2). Phosphonium salts 8 were isolated from the reaction mixture
in 60-85% yield and identified by elemental analysis and by
comparison of NMR spectra with the literature data.11
Acknowledgment. This work was supported by a research grant
from the National Science Foundation (NSF/CHE-0101021), NSERC,
and the University of Alberta.
Supporting Information Available: Synthetic and characterization
data for all new compounds (PDF) and X-ray crystallographic details
for compounds 3a and 3b (CIF). This material is available free of charge
References
(1) (a) Varvoglis, A. HyperValent Iodine in Organic Synthesis; Academic
Press: London, 1997. (b) Zhdankin, V. V.; Stang, P. J. Chem. ReV. 2002,
102, 2523.
(2) (a) Ochiai, M.; Ito, T.; Takahashi, H.; Nakanishi, A.; Toyonari, M.; Sueda,
T.; Goto, S.; Shiro, M. J. Am. Chem. Soc. 1996, 118, 7716. (b) Zhdankin,
V. V. ReV. Heteroat. Chem. 1997, 17, 133. (c) Muraki, T.; Togo, H.;
Yokoyama, M. J. Org. Chem. 1999, 64, 2883.
(3) 3b: white crystals, isolated yield 43% (after recrystallization from CH2Cl2/
ether); mp 175-176 °C. 1H NMR (CDCl3): δ 8.38 (d, 1H, J ) 8 Hz),
7.8 (d, 1H, J ) 8 Hz), 7.8-7.4 (m, 17H), 2.47 (s, 3H). 13C NMR
(CDCl3): δ 194.6, 166.9, 134.1, 133.4, 133.2, 132.6, 132.5, 130.2, 129.4,
124.7 (d, J ) 92.7 Hz, CP), 122.5, 117.4, 44.4 (d, J ) 91.8 Hz, CdP),
27.8. Anal. Calcd for C28H22IO3P‚H2O: C, 57.75; H, 4.15; I, 21.79.
Found: C, 57.81; H, 3.94; I, 22.05. ES MS: m/z (%) 565 (100),
[M + H]+, 317 (83), [M - IC6H4CO2]+. Additional synthetic and
characterization details are provided as Supporting Information.
(4) Crystallographic Data. Compound 3a (C28H22IO4P; formula weight 580.33)
crystallized in the monoclinic space group I2/a (an alternate setting of
C2/c [No. 15]) with a ) 24.6924(19) Å, b ) 9.6945(7) Å, c ) 20.2514(16)
Å; â ) 101.6756(15)°, V ) 4747.5(6) Å3, Z ) 8, F ) 1.624 g cm3, µ )
1.450 mm-1, T ) -80 °C.; R ) 0.0333 (3944 reflections with Fo
g
2
2σ(Fo2)), Rw ) 0.0812 for 4794 unique reflections with Fo2 g -3σ(Fo2).
3b‚CH3CN (C58H48ClI2NO6P2; formula weight 1206.16) crystallized in
the monoclinic space group P21/c (No. 14) with a ) 10.2285(9) Å, b )
29.139(3) Å, c ) 17.8515(17) Å; â ) 101.895(2)°, V ) 5206.4(8) Å3,
Z ) 4, F ) 1.539 g cm3, µ ) 1.373 mm-1, T ) -80 °C; R ) 0.0826
2
(4600 reflections with Fo g 2σ(Fo2)), Rw ) 0.1865 for 10 670 unique
2
reflections with Fo g -3σ(Fo2).
Scheme 2
(5) (a) Batchelor, R. J.; Birchall, T.; Sawyer, J. F. Inorg. Chem. 1986, 25,
1415. (b) Ochiai, M.; Masaki, Y.; Shiro, M. J. Org. Chem. 1991, 56,
5511.
(6) (a) Moriarty, R. M.; Prakash, I.; Prakash, O.; Freeman, W. A. J. Am.
Chem. Soc. 1984, 106, 6082. (b) Zhdankin, V. V.; Maydanovych, O.;
Herschbach, J.; Bruno, J.; Matveeva, E. D.; Zefirov, N. S. Tetrahedron
Lett. 2002, 43, 2359.
(7) Crystals were grown by diffusion of CHCl3 and hexanes into a CH3CN
solution of 3b. CHCl3 is thus the likely source of HCl in crystalline 3b.
(8) Alcock, N. W.; Countryman, R. M. J. Chem. Soc., Dalton Trans. 1977,
217.
(9) Koser, G. F.; McConville, D. B.; Rabah, G. A.; Youngs, W. J. J. Chem.
Crystallogr. 1995, 25, 857.
(10) Archer, E. M.; van Schalkwyk, T. G. D. Acta Crystallogr. 1953, 6, 88.
(11) (a) Gray, G. A. J. Am. Chem. Soc. 1973, 95, 7736. (b) Nesmeyanov, N.
A.; Berman, S. T.; Petrovskii, P. V.; Lutsenko, A. I.; Reutov, O. A. J.
Organomet. Chem. 1977, 129, 41.
This reaction represents an unusual example of a ligand exchange
on an iodine(III) center resulting in the substitution of a carbon
ligand with an oxygen ligand. This remarkable substitution is most
likely explained by a stabilizing effect of the phosphonium moiety
on the carbon leaving group in the protonated molecule of 3.
JA0277780
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J. AM. CHEM. SOC. VOL. 124, NO. 39, 2002 11615