Chemistry Letters Vol.33, No.8 (2004)
1029
(2000). b) N. G. Anderson and B. A. Keay, Chem. Rev., 101,
997 (2001). c) A. F. Littke and G. C. Fu, Angew. Chem., Int.
Ed., 41, 4176 (2002).
C. Jongsma, J. P. de Kleijn, and F. Bickelhaupt, Tetrahedron,
30, 3465 (1974).
The results of the Stille coupling using 1 as a ligand are sum-
marized in Table 3. The coupling of PhI using 1 proceeded faster
than those using Ph3P, (2-furyl)3P, and Ph3As, because of the
lower ꢀ-donating ability of 1. It is known that in the Stille cou-
pling weak ꢀ donors exhibit the good catalytic activity and that
(2-furyl)3P and Ph3As have about 10–102 times higher activity
than Ph3P.13 The trend was explained in the literature as follows.
Such ligands decrease the electron density on the palladium
atom and the transmetallation from the nucleophilic stannanes
to the electrophilic palladium, the rate-determining step, is
accelerated.
2
3
4
J. Kobayashi, T. Agou, and T. Kawashima, Chem. Lett., 32,
1144 (2003).
1
Compounds 1 and 3 were characterized by H, 13C, 31P, and
77Se NMR spectroscopy and high resolution mass spectrometry
(HRMS). 1: colorless solid, mp. 218–220 ꢂC. 1H NMR
(400 MHz, CDCl3) ꢂ 3.87 (s, 9H), 3.89 (s, 3H), 6.86 (d, J ¼
7:6 Hz, 3H), 7.03 (td, J ¼ 7:6, 2.0 Hz, 3H), 7.41 (dd, J ¼
11:1, 7.6 Hz, 3H).
Table 3. The Stille coupling using 1 as a ligand
5
6
7
a) F. J. M. Freijee and C. H. Stam, Acta Crystallogr., B36, 1247
(1980). b) N. Van der Putten and C. H. Stam, Acta Crystallogr.,
B36, 1250 (1980).
The cyclic voltammetry of parent 9-phosphatriptycene; see M.
Culcasi, Y. Berchadsky, G. Gronchi, and P. Tordo, J. Org.
Chem., 56, 3537 (1991).
Pd(dba)2 (2 mol %)
L (4 mol %)
ArI + (n-Bu)3Sn
Ar
THF, 50 °C, 2 h
L
ArI
Yielda/%
L
ArI Yielda/%
The theoretical calculations were performed using Gaussian98
program package. M. J. Frisch, G. W. Trucks, H. B. Schlegel,
G. E. Scuseria, M. A. Robb, J. R. Cheeseman,V. G. Zakrzewski,
J. A. Montgomery, Jr., R. E. Stratmann, J. C. Burant, S.
Dapprich, J. M. Millam, A. D. Daniels, K. N. Kudin, M. C.
Strain, O. Farkas, J. Tomasi, V. Barone, M. Cossi, R. Cammi,
B. Mennucci, C. Pomelli, C. Adamo, S. Clifford, J. Ochterski,
G. A. Petersson, P. Y. Ayala, Q. Cui, K. Morokuma, P.
Salvador, J. J. Dannenberg, D. K. Malick, A. D. Rabuck, K.
Raghavachari, J. B. Foresman, J. Cioslowski, J. V. Ortiz, A.
G. Baboul, B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz,
I. Komaromi, R. Gomperts, R. L. Martin, D. J. Fox, T. Keith,
M. A. Al-Laham, C. Y. Peng, A. Nanayakkara, M.
Challacombe, P. M. W. Gill, B. Johnson, W. Chen, M. W.
Wong, J. L. Andres, C. Gonzalez, M. Head-Gordon, E. S.
Replogle, and J. A. Pople, ‘‘Gaussian 98, Revision A.11,’’
Gaussian, Inc., Pittsburgh PA (2001).
1
1
1
PhI
p-MeOC6H4I
p-CF3C6H4I
95
64
36
Ph3P
(2-furyl)3P PhI
Ph3As PhI
PhI
4
84
76
aEstimated by 1H NMR spectroscopy.
The reaction of p-MeOC6H4I gave the lower yield, because
its electron-rich nature decreased the rate of oxidative addition.
Although the oxidative addition to electron-deficient ArX usual-
ly should proceed readily, the yield of the reaction of p-
CF3C6H4I was much lower than that of PhI, presumably because
of the catalyst decomposition or generation of inactive com-
plexes. As shown in Scheme 1, the Heck reaction using 1 as a
ligand gave trans-stilbene in 53% yield, which was superior to
the results of Ph3P (6%),14 (2-furyl)3P (13%), and Ph3As
(42%). The result is quite reasonable taking into account that
the migratory-insertion of alkenes, the rate-determining step, is
accelerated by weak ꢀ donors in the Heck reaction.14
8
9
D. W. Allen and B. F. Taylor, J. Chem. Soc., Dalton Trans.,
1982, 51.
4: yellow solid, mp 421–423 ꢂC (dec.) 1H NMR (500 MHz,
CDCl3) ꢂ 3.81 (s, 3H), 3.90 (s, 9H), 6.98 (d, J ¼ 8:1 Hz, 3H),
7.19 (td, J ¼ 7:6, 3.2 Hz, 3H), 7.63 (dd, J ¼ 14:0, 7.3 Hz,
3H); 13C{1H} NMR (125 MHz, CDCl3) ꢂ 56.69 (s), 59.01 (s),
90.91 (d, J ¼ 8:6 Hz), 117.69 (s), 125.52 (d, J ¼ 21:5 Hz),
126.79 (d, J ¼ 15:6 Hz), 136.30 (s), 137.75 (d, J ¼ 36:1 Hz),
Pd(dba)2 (1 mol%)
L (2 mol%), NEt3 (1 equiv.)
Ph
PhI
+ Ph
Ph
MeCN, 80 °C, 45 min.
All yields were estimated by1H NMR spectroscopy.
2
1
157.09 (d, J ¼ 23:3 Hz), 196.40 (d, JCP ¼ 7:6 Hz, JCW
¼
124 Hz), 197.06 (d, 2JCP ¼ 25:5 Hz, 1JCW ¼ 140 Hz);
Scheme 1.
31P{1H} NMR (202 MHz, CDCl3) ꢂ 11.6 (s, JPW ¼ 261 Hz);
1
In summary, we have succeeded in the synthesis of the first
metal complex bearing a 9-phosphatriptycene. The low ꢀ-donat-
ing ability of 1 was evaluated by various methods. On the basis
of such an electronic property, 1 accelerated the Stille coupling
and the Heck reaction of PhI compared with well-known weak
ꢀ donors, (2-furyl)3P and Ph3As.
IR (KBr): ꢃ (CO) 2075, 1963, 1913 cmꢁ1; IR (hexane): ꢃ
(CO) 2075, 1946 cmꢁ1; HRMS (FABþ): m=z Calcd. for
C28H21O9P186W 718.0475; Found 718.0471 (Mþ).
10 The tungsten and molybdenum pentacarbonyl complexes
bearing a 8-phosphathiophenetriptycene; see A. Ishi, I. Takaki,
J. Nakayama, and M. Hoshino, Tetrahedron Lett., 34, 8255
(1993).
11 W. Buchner and W. A. Schenk, Inorg. Chem., 23, 132 (1984).
12 The ꢀ-donating ability of a 9,10-silaphosphatriptycene and the
Stille coupling using it as a ligand were reported previously: A.
Kawachi, Y. Kaneta, and K. Tamao, 81st Annual Meeting of the
Chemical Society of Japan, Tokyo, March 2002, Abstr.,
No. 4G6-28; The Heck reaction using the 9,10-silaphosphatrip-
tycene: K. Tamao, Private Communication (2004).
13 V. Farina and B. Krishnan, J. Am. Chem. Soc., 113, 9585
(1991).
This work was supported by Grant-in-Aid for The 21st
Century COE Program for Frontiers in Fundamental Chemistry
(T. K.) and for Scientific Research (T. K.) from the Ministry of
Education, Culture, Sports, Science and Technology of Japan.
We thank Tosoh Finechem Corporation and Shin-etsu Chemical
Corporation for the generous gifts of alkyllithiums and phenyl-
silane, respectively.
14 G. P. F. van Strijdonck, M. D. K. Boele, P. C. J. Kamer, J. G. de
Vries, and P. W. N. M. van Leeuwen, Eur. J. Inorg. Chem.,
1999, 1073.
References and Notes
a) J. Tsuji, ‘‘Transition Metal Reagents and Catalysts: Innova-
tions in Organic Synthesis,’’ John Wiley & Sons, Chicester
1
Published on the web (Advance View) July 19, 2004; DOI 10.1246/cl.2004.1028