unlikely. On the contrary, the ipso-carbon atom of the sub-
stituted tropylium ion has a large coefficient in the LUMO.
Therefore, a large contribution of P–O bonding structure 17-A
in the intermediate 17 favors the intramolecular nucleophilic
attack on C8a.
Reaction of 1a with phenyl isocyanate 3
A solution of 1a (197 mg, 0.5 mmol) and 3 (119 mg, 1 mmol) in
dioxane (2 cm3) was heated under reflux for 9 h. The reaction
mixture was concentrated and the residue was chromato-
graphed on SiO2. The fractions eluted with hexane–AcOEt
(1 : 1) were concentrated, and the resulting residue was separ-
ated by TLC on SiO2 (hexane–AcOEt: 2 : 1) to give 7a, 8a, and
14. Results are summarized in Table 2.
In summary, the 31P and 13C NMR spectral studies and the
X-ray crystallographic analysis revealed that 1a–d exist as
resonance hybrids of canonical structures A, B, and C. A linear
correlation between 31P chemical shifts and P1–O1 bond
lengths is obtained. The contribution of canonical structure A
decreases gradually in the order of 1a > 1c > 1b > 1d in the solid
state. On the basis of a linear correlation between P1–O1 bond
lengths and θsum, it is clarified that the increase in P1–O1 bond-
ing character causes a change in configuration of the phos-
phorus atom from a tetrahedral to a trigonal bipyramidal
arrangement. On the basis of the study, the structure of 2 is
confirmed as well. On the other hand, the electron-donating
methyl group makes 1a have a large contribution of P–O bond-
ing structure A. On the contrary, the electron-withdrawing
nitrile group generally stabilizes ylides, and thus, 1d has a large
contribution of canonical structures B and C. It is established
that reactions of 1a with heterocumulenes give not only pro-
ducts arising from a contribution of structure A but also
products derived from structures B and C. The reaction
provides a methodology for constructing new derivatives of
heteroazulenes.
For 7a. Orange plates; mp 108–109 ЊC (from EtOH) (lit.18
105–106 ЊC); δH (500 MHz) 2.02 (3H, s, Me), 6.67 (1H, dd,
J 11.0, 8.4, H-6), 6.77 (1H, d, J 9.0, H-8), 6.84 (1H, dd, J 11.0,
9.0, H-7), 6.91 (1H, dd, J 11.4, 8.4, H-5), 7.08 (1H, d, J 11.4,
H-4); δC (125.6 MHz) 7.8, 108.0, 111.8, 126.2, 129.4, 131.8,
133.7, 147.4, 157.6, 170.2; νmax (CHCl3)/cmϪ1 1745, 1271; m/z
(rel. int.) 160 (Mϩ, 33%), 131 (100) (Found: C, 75.1; H, 4.9.
C10H8O2 requires C, 74.99; H, 5.03%).
For 8a. Red needles; mp 134–135 ЊC (from EtOH); δH
(500 MHz) 2.01 (3H, s, Me), 6.13 (1H, d, J 8.8, H-8), 6.14 (1H,
dd, J 11.4, 8.1, H-6), 6.35 (1H, dd, J 11.4, 8.8, H-7), 6.42 (1H,
dd, J 11.6, 8.1, H-5), 6.67 (1H, d, J 11.6, H-4), 7.08 (1H, t, J 7.2,
p-Ph), 7.26 (2H, d, J 8.4, o-Ph), 7.32 (2H, dd, J 8.4, 7.2, m-Ph);
δC (125.6 MHz) 8.4, 107.0, 115.7, 123.4, 123.7, 125.5, 127.2,
128.7, 131.3, 132.1, 142.0, 146.6, 158.9, 161.5; νmax (CHCl3)/
cmϪ1 1659, 1267; m/z (rel. int.) 235 (Mϩ, 75%), 77 (100)
(HRMS: Found: Mϩ ϩ 1, 236.1075. C22H16O requires Mϩ ϩ 1,
236.1059).
Experimental
For 14. Orange needles; mp 184–185 ЊC (from EtOH);
δH (500 MHz) 2.20 (3H, s, Me), 6.59 (1H, d, J 9.0, H-8), 6.72
(1H, dd, J 11.0, 8.4, H-6), 6.82 (1H, dd, J 11.0, 9.0, H-7), 6.94
(1H, dd, J 11.4, 8.4, H-5), 7.33 (2H, d, J 8.4, o-Ph), 7.39 (1H, d,
J 11.4, H-4), 7.46 (1H, t, J 7.5, p-Ph), 7.54 (2H, dd, J 8.4, 7.5,
m-Ph); δC (125.6 MHz) 8.1, 111.2, 111.9, 126.7, 128.1, 128.5,
128.6, 129.4, 130.1, 130.4, 134.6, 140.4, 145.3, 169.2; νmax
(CHCl3)/cmϪ1 1667; m/z (rel. int.) 235 (Mϩ, 83%), 77 (100)
(Found: C, 81.4; H, 5.5; N, 5.9. C16H13NO requires C, 81.68;
H, 5.57; N, 5.95%).
IR spectra were recorded on a Perkin-Elmer 1640 spectrometer.
Mass spectra and high-resolution mass spectra were run on
JMS-AUTOMASS 150 and JMS-SX102A spectrometers. H
1
NMR spectra and 13C NMR spectra were recorded on JNM-
AL300, JNM-GSX400, and JNM-LA500 spectrometers using
CDCl3 as a solvent, and the chemical shifts are given relative to
internal SiMe4 standard; J-values are given in Hz. 31P NMR
(109.3 MHz) spectra were recorded on a JNM-EX270 spectro-
meter, and the chemical shifts are given relative to external
aqueous 85% H3PO4 standard (the negative value denotes sig-
nals appearing at higher field than the standard). The solid state
31P MAS NMR (161.8 MHz) spectra were recorded on a JNM-
GSX400 spectrometer, and the chemical shifts are given relative
to external aqueous 85% H3PO4 standard (the negative value
denotes signals appearing at higher field than the standard).
Microanalysis was performed at the Materials Character-
ization Central Laboratory, Waseda University. Mps were
recorded on a Yamato MP-21 apparatus and are uncorrected.
All the reactions were carried out under anhydrous conditions
and dry nitrogen atmosphere. Dioxane refers to 1,4-dioxane
throughout.
Reaction of 1a with diphenylcarbodiimide 4
A solution of 1a (99 mg, 0.25 mmol) and 4 (97 mg, 0.5 mmol) in
anisole (5 cm3) was heated under reflux for 12 h. The reaction
mixture was then separated by TLC on SiO2 (hexane–AcOEt:
3 : 1) to give 8a. The results are summarized in Table 2. The
physical data are identical with those of the authentic specimen.
Reaction of 1a with phenyl isothiocyanate 5
A solution of 1a (197 mg, 1 mmol) and 5 (270 mg, 2 mmol)
in dioxane (3 cm3) was heated under reflux for 2 h. The reac-
tion mixture was concentrated and the residue was chromato-
graphed on SiO2. The fractions eluted with hexane–AcOEt
(1 : 1) were concentrated and the residue was separated by TLC
on SiO2 (hexane–AcOEt: 1 : 1) to give 15 and 16. Results are
summarized in Table 2.
Preparationof3-methyl-2,2,2-triphenyl-2H-cyclohepta[d][1,2ꢀ5]-
oxaphosphole 1a
A solution of ethyltriphenylphosphonium bromide (11.13 g,
30 mmol) and tert-BuOK (3.36 g, 30 mmol) in THF (30 cm3)
was stirred at rt for 0.5 h. To the solution was added 2-chloro-
tropone (2.11 g, 15 mmol), and the mixture was stirred for 2 h at
rt. After the THF was removed in vacuo, the resulting residue
was dissolved in CH2Cl2 and filtered to remove insoluble
materials. The filtrate was concentrated and the residue was
chromatographed on Al2O3 using hexane–AcOEt (1 : 1) as the
eluent to give 1a (3.46 g, 59%).
For 15. Dark green plates; mp 108–109 ЊC (from EtOH); δH
(500 MHz) 2.44 (3H, s, Me), 6.72–6.77 (1H, m, H-8), 6.96–7.05
(2H, m, H-6, 7), 7.15–7.19 (1H, m, H-5), 7.32 (2H, d, J 8.6,
o-Ph), 7.55 (1H, t, J 7.3, p-Ph), 7.58–7.62 (3H, m, m-Ph, H-4);
δC (125.6 MHz) 10.7, 115.1, 125.3, 128.2, 129.2, 129.3, 129.6,
131.1, 131.4, 131.5, 136.7, 139.1, 149.5, 187.8; νmax (CHCl3)/
cmϪ1 1577, 1542, 1495, 1427, 1383, 1372, 1330, 1270, 1070,
1024; m/z (rel. int.) 251 (Mϩ, 33%), 77 (100) (Found: C, 76.6;
H, 5.5; N, 5.6. C16H13NS requires C, 76.46; H, 5.21; N, 5.57%).
For 1a. Reddish plates; mp 208–209 ЊC (from EtOH) (lit.9
212–213 ЊC); δH (500 MHz) 1.44 (3H, d, JHP 17.6, Me), 5.82
(1H, d, J 10.0, H-8), 6.05 (1H, dd, J 10.1, 9.6, H-6), 6.56 (1H,
dd, J 10.1, 10.0, H-7), 6.69 (1H, dd, J 11.3, 9.6, H-5), 6.72 (1H,
d, J 11.3, H-4), 7.20–7.60 (15H, br s, Ph); νmax (CHCl3)/cmϪ1
1598, 1564, 1504.
For 16. Orange needles; mp 153–154 ЊC (from EtOH);
δH (500 MHz) 2.55 (3H, s, Me), 5.89 (1H, s, NH), 6.63 (1H, dd,
J 11.0, 8.1, H-7), 6.94 (1H, d, J 12.1, H-5), 6.99 (1H, t, J 7.3,
p-Ph), 7.02 (1H, dd, J 12.1, 8.1, H-6), 7.03 (2H, d, J 8.6, o-Ph),
1022
J. Chem. Soc., Perkin Trans. 2, 2002, 1017–1023