1
128
S. Iyer, A. Jayanthi
LETTER
TON and TOF. The activity of these complexes are simi-
lar to previously reported oxime and amine palladacycle
complexes and the stability and reactivity is increased by
the N-heterocyclic carbenes compared to the phosphine
ligands.
(10) All compounds reported are known and were characterized
by spectroscopic methods
(a) Mizoroki–Heck reaction with benzophenone oxime
carbene palladacycle (Cat 3) : To 5.175 g (25 mmol) of 1-
bromonaphthalene, styrene (3.03 g, 30 mmol) and 25 mL N-
methylpyrrolidinone were added to, followed by 2.49 g (30
mmol) of NaOAc and 0.00022 g (0.0004 mmol) of the (Cat
3
) benzophenone oxime palladacycle carbene catalyst. The
Acknowledgement
reaction mixture was heated to 140–150 °C in an oil bath
until the bromonaphthalene was completely consumed (36
h). HCl (10%, 100 mL) was added to the reaction mixture
and extracted with ethyl acetate (3 × 100 mL). Washing the
organic extracts with brine, drying over anhydrous Na SO ,
We thank the DST for a research grant and the CSIR for a JRF to AJ.
References
2
4
concentration on a rotary evaporator and purification by
column chromatography (silica gel : 100–200 mesh) gave
(
(
1) NCL Communication No.: 6643
2) Herrmann, W. A.; Elison, M.; Fischer, J.; Koecher, G.;
Artus, G. J. Angew. Chem., Int. Ed. Engl. 1995, 34, 2371.
3) Herrmann, W. A.; Brossmer, C.; Oefele, K.; Reisinger, C.-
P.; Priermeier, T.; Beller, M.; Fischer, H. Angew. Chem., Int.
Ed. Engl. 1995, 34, 1244.
5.32 g (92.6%, TON 61, 956) of E-1-naphthylstilbene.
(
b) Suzuki coupling of bromobenzene with phenyl boronic
(
acid catalyzed by carbene palladacycle (Cat – 2) :
Bromobenzene (0.314 g, 2 mmol), phenyl boronic acid
(
0.367 g, 3 mmol), catalyst (3, 0.0004 g, 0.0007 mmol) and
(
4) Scholl, M.; Ding, S.; Lee, C. W.; Grubbs, R. H. Org. Lett.
K PO (0.920 g, 4.34 mmol) were dissolved in DMF (5 mL)
3
4
1999, 1, 953.
and the reaction mixture heated to 120 °C for 24 h. The
biphenyl product was isolated by addition of HCl (10%, 25
mL) and extracted with ethyl acetate followed by
(
(
5) Iyer, S.; Ramesh, C. Tetrahedron Lett. 2000, 41, 8981.
6) Alonson, D. A.; Najera, C.; Pacheco, M. C. Org. Lett. 2000,
2, 1823.
purification by column chromatography (silica gel : 100–
(
7) Iyer, S.; Jayanthi, A.; Kulkarni, G. M.; Subramanyam, S.;
Kashinath, D. K., unpublished results from our research
group.
2
(
2
00 mesh) in 73.3% (0.226 g, TON 2, 096) yield.
c) Biaryl coupling catalyzed by carbene palladacycle (Cat –
) and K CO . 2-Bromopyridine (0.158 g, 1.0 mmol),
2
3
(
(
8) Iyer, S.; Jayanthi, A. Tetrahedron Lett. 2001, 42, 7877.
9) (a) Onoue, H.; Minami, K.; Nakagawa, K. Bull. Chem. Soc.
Jpn. 1979, 43, 3480. (b) Hiraki, K.; Onishi, M.; Sewaki, K.;
Sugino, K. Bull. Chem. Soc. Jpn. 1978, 51, 2548.
K CO (0.165 g, 1.2 mmol), catalyst (2, 0.0017 g, 0.003
2
3
mmol) were dissolved in DMF (5 mL) and heated to 140 °C
for 24 h. The bipyridyl was isolated by the usual extractive
procedure with water and ethyl acetate. Purification by
column chromatography (silica gel: 100–200 mesh) gave
1
0
.025 g (16%) yield of the 2,2¢-bipyridyl. H NMR (d, 200
MHz, CDCl ) 8.69–8.71 (d, 2 H), 8.39–8.43 (d, 8 Hz, 2 H),
3
7.80–7.88 (m, 2 H), 7.27–7.36 (m, 2H).
Synlett 2003, No. 8, 1125–1128 ISSN 1234-567-89 © Thieme Stuttgart · New York