2604
J . Org. Chem. 1996, 61, 2604-2605
Sch em e 1
Com p lete Regioselection in
P a lla d iu m -Ca ta lyzed Ar yla tion a n d
Alk en yla tion of Allylic Alcoh ols w ith
Hyp er va len t Iod on iu m Sa lts
Suk-Ku Kang,* Hong-Woo Lee, Su-Bum J ang,
Tae-Hyun Kim, and Sung-J ae Pyun
Sch em e 2
Department of Chemistry, Sung Kyun Kwan University,
Natural Science Campus, Suwon 440-746, Korea
Received October 31, 1995
The formation of a carbon-carbon bond by palladium-
catalyzed coupling of aryl or vinyl halides with olefins,
known as the Heck reaction, has become a powerful tool
in organic chemistry.1 In the case of allylic alcohols,
palladium-catalyzed reaction of organic halides usually
affords â-substituted ketones or aldehydes rather than
the â-substituted allylic alcohols (Scheme 1).2
This is in contrast to the result reported9 that the reaction
of allylic alcohols with diaryliodonium bromide in the
presence of palladium catalyst and base yielded the
corresponding arylpropanals.
The results of Pd-catalyzed coupling of allylic alcohols
with hypervalent iodonium salts in dry DMF (nonaque-
ous conditions) and in CH3CN/H2O (5:1) (aqueous condi-
tions) are summarized in Table 1. The allylic alcohol 1
(1 equiv) was reacted with diphenyliodonium tetrafluo-
roborate10 (1 equiv) in the presence of NaHCO3 using
phosphine-free Pd(OAc)2 (2 mol %) as catalyst in dry
DMF (nonaqueous conditions) at room temperature for
1.5 h to afford the phenyl-substituted allylic alcohol 4 as
the sole product in 87% yield (method A, entry 1, Table
1).11-13 Under the same conditions using CH3CN/H2O (5:
1) (aqueous conditions), the reaction proceeded faster.
Stirring for 0.5 h afforded the cinnamyl alcohol 4 in 89%
yield (method B, entry 1, Table 1).13,14 When 1 mol %
and 0.5 mol % of Pd(OAc)2 were used, the yields were
reduced to 83% and 81%, respectively.15 When the
reaction was conducted at 60 °C under the same condi-
tions, only the phenyl-substituted allylic alcohol 4 was
obtained in a rather low yield (40%) without any forma-
J effery3 reported that in the presence of a stoichiomet-
ric amount of silver acetate or silver carbonate, a highly
selective formation of the substituted allylic alcohols can
be achieved. Cacchi4 reported that Pd(0)-catalyzed reac-
tion of allylic alcohols with triflates in the presence of
Et3N provided two isomeric substituted allylic alcohols.
Tamaru5 utilized O-substituted allylic alcohols to direct
the Pd(0)-catalyzed coupling without elimination of pro-
ton adjacent to the oxygen-bearing carbon. Recently, we
have found that the Pd-catalyzed coupling of allylic diols
with iodobenzene in the presence of Pd(OAc)2 and n-Bu3P
as catalysts using K2CO3 as base afforded phenyl-
substituted allylic diols and using Et3N as base under
the same conditions afforded phenyl-substituted R-hy-
droxy ketones.6 However, our efforts to get phenyl-
substituted allylic alcohols with iodobenzenes and allylic
alcohols in the presence of Pd-catalysts by adjusting the
reaction conditions were fruitless as we obtained a
mixture of substituted ketones and allylic alcohols.6
Finally, we have found that the coupling reaction of
hypervalent iodonium salts7 with allylic alcohols in the
presence of phosphine-free Pd(OAc)2 catalyst afforded the
substituted allylic alcohols as the sole products under
mild conditions with high catalytic efficiency (Scheme 2).8
(9) Nishimura, A.; Uchiyama, M.; Suzuki, T.; Yamazaki, Y. Nippon
Kagaku Kaishi 1985, 558; Chem. Abstr. 1986, 104, 109137.
(10) Ochiai, M.; Sumi, K.; Takaoka, Y.; Shiro, M.; Fujita, E.
Tetrahedron 1988, 44, 4095.
(11) Water only can be used as solvent, but the yield was lower (77%)
with some side products after stirring at room temperature for 45 min.
The reactions proceeded in the absence of base in CH3CN/H2O(5:1) at
room temperature for 30 min with some side products in 73% yield.
In our hands, with diphenyliodonium tetrafluoroborate (1 equiv) and
Pd(OAc)2 (2 mol %) in H2O without using base cinnamyl alcohol (4)
was obtained in 71% yield, although the reaction was not clean.
(12) In the literature, the coupling of alkenyl(phenyl)iodonium salts
with olefins, 3 equiv of olefins were used. See ref 8a. In the palladium-
catalyzed cross-coupling of alkenyl(phenyl)iodonium salts with orga-
notin compounds, for the iodonium salts excess organotin compounds
were used. See ref 8b.
(13) Diphenyliodonium and alkenyl(phenyl)iodonium triflates can
be used. In our hands, with tetrafluoroborate the reactions were more
clean.
(14) The reaction of allylic alcohol 1 with PhOTf in the presence of
phosphine-free Pd(OAc)2 catalyst and NaHCO3 in DMF at room
temperature did not give the coupled product and only the starting
material was recovered. However, in the presence of Pd(PPh3)4 catalyst
and K2CO3 or Et3N as base, â-substituted aldehyde was obtained in
91 and 87% yields, respectively. In the case of iodobenzene with Pd-
(OAc)2 at catalyst, the â-substituted aldehyde was afforded.
(1) (a) Heck, R. F. Org. React. 1982, 27, 345. (b) Heck, R. F. Acc.
Chem. Res. 1979, 12, 146. (c) Meijere, A. de.; Meyer, F. E. Angew.
Chem., Int. Ed. Engl. 1994, 33, 2379. (d) Davis, G. D., J r.; Hallberg,
A. Chem. Rev. 1989, 89, 1433.
(2) (a) Melpolder, J . B.; Heck, R. F. J . Org. Chem. 1976, 41, 265.
(b) Chalk, A. J .; Magennis, S. A. Ibid. 1976, 41, 273. (c) Frank, W. C.;
Kim, Y. C.; Heck, R. F. J . Org. Chem. 1978, 43, 2947. (d) Tamaru, Y.;
Yamada, Y.; Yoshida, Z.-i. J . Org. Chem. 1978, 43, 3396. (e) Tamaru,
Y.; Yamada, Y.; Yoshida, Z.-i. Tetrahedron 1979, 35, 329 and references
therein. (f) J effery, T. J . Chem. Soc., Chem. Commun. 1984, 1287. (g)
Masters, J . J .; J ung, O. K.; Bornmann, W. G.; Danishefsky, S.
Tetrahedron Lett. 1993, 34, 7253.
(3) (a) J effery, T. Tetrahedron Lett. 1991, 32, 2121. (b) J effery, T.
J . Chem. Soc., Chem. Commun. 1991, 1133.
(4) Bernocchi, E.; Cacchi, S.; Crattini, P. G.; Morera, E.; Ortar, G.
Tetrahedron Lett. 1992, 33, 3073.
(5) Ono, K.; Fugami, K.; Tanaka, S.; Tamaru, Y. Tetrahedron Lett.
1994, 35, 4133.
(6) Kang, S.-K.; J ung, K.-Y.; Park, C.-H.; Namkoong, E.-Y.; Kim,
T.-H. Tetrahedron Lett. 1995, 36, 6287.
(7) For recent reviews: (a) Stang, P. J . Angew. Chem., Int. Ed. Engl.
1992, 31, 274. (b) Moriarty, R. M.; Viad, R. K. Synthesis 1990, 431.
(c) Ochiai, M. Rev. Heteroatom. Chem. 1989, 2, 92.
(8) Pd-catalyzed C-C bond formation: (a) Moriarty, R. M.; Epa, W.
R.; Awasthi, A. K. J . Am. Chem. Soc. 1991, 113, 6315. (b) Moriarty,
R. M.; Epa, W. R. Tetrahedron Lett. 1992, 33, 4095. (c) Hinkle, R. J .;
Poulter, G. T.; Stang, P. J . J . Am. Chem. Soc. 1993, 115, 11626. (d)
Kang, S.-K.; J ung, K. Y.; Park, C.-H.; J ang, S.-B. Tetrahedron Lett.
1995, 36, 8047.
(15) Of the catalysts tested, Pd(OAc)2 was the most effective. The
reaction could be carried out without base. However, we could not
get a higher yield in the absence of the base.
0022-3263/96/1961-2604$12.00/0 © 1996 American Chemical Society