Full text of DOI:10.1021/jo9814086

6450
J . Org. Chem. 1998, 63, 6450-6451
To a mixture of CrCl2 (4.0 equiv) and B12 (0.10 equiv) in
B12-Ca ta lyzed Gen er a tion of Allylic
Ch r om iu m Rea gen ts fr om 1,3-Dien es, Cr Cl2,
a n d Wa ter
dry DMF was added a solution of 3-phenylpropanal and 2,3-
dimethyl-1,3-butadiene (2.0 equiv) in DMF. The deep green
color of the mixture gradually darkened with stirring.10
Then, the mixture was heated to 40 °C, and a DMF solution
of water (0.2 M, 1.0 equiv) was added over a period of 2 h.
After usual workup with water, homoallylic alcohol 1 was
obtained in 90% yield (eq 1).12 The coupling reaction only
Kazuhiko Takai* and Chika Toratsu
Department of Applied Chemistry, Faculty of Engineering,
Okayama University, Tsushima, Okayama 700-8530, J apan
Received J uly 20, 1998
Although allylic chromium reagents are useful tools for
stereoselective carbon-carbon bond formation under mild
conditions, their source has been almost limited to allylic
halides1 and pseudohalides.2 Recently, we have reported the
generation of allylic chromium compounds by addition of
alkyl radicals to 1,3-dienes and successive one-electron
reduction with chromium(II).3 However, the method could
not provide a hydrogen radical, and thus, a simple reaction
between a diene and an aldehyde was not realized. We
report here a novel access to the reagents from 1,3-dienes
and a chromium hydride equivalent generated from CrCl2,
B12 (cyanocobalamin), and water.
Addition of a metal hydride to a 1,3-diene produces an
allylic metal compound when the hydride adds to the C-1 of
the diene and the metal adds to the C-2 or C-4.4 Although
there is no direct method to provide appropriate chromium
hydride species,5 cobalt hydride species react with a 1,3-
diene in the desired fashion to give allylic cobalt com-
pounds.6,7 An organic moiety on cobalt compounds smoothly
transfers to chromium by treatment with chromium(II).8 In
addition, a cobalt hydride species of B12 can be prepared by
treatment of low-valent B12s with water.9-11 These observa-
tions prompted us to explore the novel preparation of allylic
chromium reagents from 1,3-dienes with a cobalt catalyst.
13
proceeded with the addition of B12
.
For the reaction to go
to completion, it is important that the reactions between
organochromium reagents and carbonyl compounds are not
disturbed by the presence of 1-3 equiv of a proton source.14
However, the addition of water in one portion caused the
reaction to not go to completion, suggesting that the allylic
chromium species was protonated to some extent. When
D2O in DMF was added in one portion to the reaction
mixture, deuterium was introduced at the methyl position
with a content of 48%.15
The results obtained with several kinds of 1,3-dienes are
summarized in Table 1. The diastereoselectivity of the
reaction between the crotylchromium species and nonanal
was 72/28 (Table 1, entry 1), which is almost equal to the
ratio observed for the reaction with crotyl bromide and CrCl2
in DMF.2a This is explained by a fast equilibrium between
(E)- and (Z)-crotylchromium in the solvent.2c Therefore,
geometrically fixed allylic chromium compounds derived
from 1,3-cyclohexadiene and 3-methylene-1-cyclohexene,
respectively, produced each of the diastereomers exclusively
(entries 5 and 6). A 1,3-diene having an s-trans configura-
tion also gave the corresponding allylic chromium reagent
(entry 6). The result suggests that the hydrocobaltation step
proceeds in a 1,2-fashion.6 In the case of unsymmetrical 1,3-
dienes, the cobalt hydride added selectively to form more
stable allylic radicals after cleavage of cobalt-carbon bonds
(entries 2-8).6 Selective formation of (E)-homoallylic alcohol
by the reaction between 2-propenylidenecyclohexane and
3-phenylpropanal possibly stemmed from a six-membered
transition state of less steric demand (entry 7). The gener-
ated allylic chromium species showed aldehyde-selective
addition (entry 4) as did those obtained from allylic halides
and CrCl2.2a 2-(Benzyloxy)-1,3-butadiene can also be em-
ployed for the reaction producing stereoselectively an anti
adduct (entry 8).16
(1) For reviews of organochromium reagents, see: (a) Takai, K.; Utimoto,
K. J . Synth. Org. Chem. J pn. 1988, 46, 66. (b) Saccomano, N. A. In
Comprehensive Organic Synthesis; Trost, B. M., Ed; Pergamon Press:
Oxford, 1991; Vol. 1, p 173. (c) Cintas, P. Synthesis 1992, 248.
(2) (a) Allyl tosylate: Okude, Y.; Hirano, S.; Hiyama, T.; Nozaki, H. J .
Am. Chem. Soc. 1977, 99, 3179. (b) Allylic mesylate: Kato, N.; Tanaka, S.;
Takeshita, H. Chem. Lett. 1986, 1989. (c) Allylic phosphate: Takai, K.;
Nozaki, H. Abstr. 4th ICOS Tokyo 1982, B-II-2302. J ubert, C.; Nowotny,
S.; Kornemann, D.; Antes, I.; Tucker, C. E.; Knochel, P. J . Org. Chem. 1992,
57, 6384. Nowotny, S.; Tucker, C. E.; J ubert, C.; Knochel, P. J . Org. Chem.
1995, 60, 2762. (d) 1,3-Diene monoepoxide: Fujimura, O.; Takai, K.;
Utimoto, K. J . Org. Chem. 1990, 55, 1705.
(3) Takai, K.; Matsukawa, N.; Takahashi, A.; Fujii, T. Angew. Chem.,
Int. Ed. Engl. 1998, 37, 152.
(4) For some representative examples, see: (a) Ti: Sato, F.; Ishikawa,
H.; Sato, M. Tetrahedron Lett. 1980, 21, 365. Klei, B.; Teuben, J . H.; de
Liefde Meijer, H. J . J . Chem. Soc., Chem. Commun. 1981, 342. Kobayashi,
Y. Umeyama, K.; Sato, F. J . Chem. Soc., Chem. Commun. 1984, 621. Gao,
Y.; Urabe, H.; Sato, F. J . Org. Chem. 1994, 59, 5521. Szymoniak, J .; Thery,
N.; Mo¨ıse, C. Synlett 1997, 1239. (b) Ni: Sato, Y.; Takimoto, M.; Hayashi,
K.; Katsuhara, T.; Takagi, K.; Mori, M. J . Am. Chem. Soc. 1994, 116, 9771.
Sato, Y.; Saito, N.; Mori, M. Tetrahedron Lett. 1997, 38, 3931. (c) Si:
Kobayashi, S.; Nishio, K. J . Org. Chem. 1994, 59, 6620. (d) B: Sato, M.;
Nomoto, Y.; Miyaura, N.; Suzuki, A. Tetrahedron Lett. 1989, 30, 3789.
(5) Darensbourg, M. Y.; Deaton, J . C. Inorg. Chem. 1981, 20, 1644. Kao,
S. C.; Darensbourg, M. Y. Organometallics 1984, 3, 646.
(6) (a) Co(SCN)(PPh3)3, H2: Nakayama, T.; Kanai, H. Bull. Chem. Soc.
J pn. 1985, 58, 16. (b) HCo(dmgH)2py: Howell, A. R.; Pattenden, G. J . Chem.
Soc., Chem. Commun. 1990, 103. (c) HCo(CN)53-: Reger, D. L.; Habib, M.
M.; Fauth, D. J . J . Org. Chem. 1980, 45, 3860. Lee, J .-T.; Alper, H. J . Org.
Chem. 1990, 55, 1854. (d) Co(acac)3, Et2AlCl, PPh3: Takacs, J . M.; Mehrman,
S. J . Tetrahedron Lett. 1996, 37, 2749.
(12) Under the standard reaction conditions (eq 1), compounds were
recovered in the following order: 1-dodecene (90%); 1-dodecyne (92%);
1-chlorododecane (96%); nonanal diethylene acetal (94%); ethyl octanoate
(93%); nonanenitrile (90%).
(13) When 2-methyl-1,3-tetradecadiene and 3-phenylpropanal were treated
at 25 °C with CrCl2 and water in the absence of B12, the 1,3-diene was
recovered in 95% yield after 24 h of stirring. The reaction also proceeded
by the addition of cobalt phthalocyanine (2.5 mol %), although the yield of
1 was only 58%.
(7) Bo¨nnemann, H. Angew. Chem., Int. Ed. Engl. 1973, 12, 964.
(8) (a) Espenson, J . H.; Shveima, J . S. J . Am. Chem. Soc. 1973, 95, 4468;
Espenson, J . H.; Sellers, T. D., J r. J . Am. Chem. Soc. 1974, 96, 94. (b) Takai,
K.; Nitta, K.; Fujimura, O.; Utimoto, K. J . Org. Chem. 1989, 54, 4732.
(9) Boos, R. N.; Carr, J . E.; Conn, J . B. Science 1953, 117, 603. Beaven,
G. H.; J ohnson, E. A. Nature 1955, 176, 1264.
(14) (a) Kauffmann, T.; Abel, K.; Bonrath, W.; Kolb, M.; Mo¨ller, T.; Pahde,
C.; Raedeker, S.; Robert, M.; Wensing, M.; Wichmann, B. Tetrahedron Lett.
1986, 27, 5351. Kauffmann, T. Synthesis 1995, 745. (b) Kato, N.; Takeshita,
H.; Kataoka, H.; Ohbuchi, S.; Tanaka, S. J . Chem. Soc., Perkin Trans. 1
1989, 165.
(15) Although the reaction slowly proceeded without addition of water,
it did not go to completion. Quenching the reaction mixture with D2O did
not give the deuterated product, probably because unremoved water in the
solvent and hydroxyl group of B12 supply protons.
(10) Schrauzer, G. N.; Holland, R. J . J . Am. Chem. Soc. 1971, 93, 4060.
(11) For reviews of carbon-carbon bond formation using B12, see:
Scheffold, R.; Rytz, G.; Walder, L.; Orlinski, R.; Chimonczyk, Z. Pure Appl.
Chem. 1983, 55, 1791. Scheffold, R. Chimia 1985, 39, 203.
(16) Takai, K.; Nitta, K.; Utimoto, K. Tetrahedron Lett. 1988, 29, 5263.
S0022-3263(98)01408-X CCC: $15.00 © 1998 American Chemical Society
Published on Web 09/02/1998

Communications
J . Org. Chem., Vol. 63, No. 19, 1998 6451
Ta ble 1. Rea ction s betw een 1,3-Dien es a n d Ald eh yd es Med ia ted by Cr Cl2, B12, a n d Wa ter a
chloride,9 affords hydridocobalamin by reaction with water.10
Hydrocobaltation of the cobalt hydride species to a 1,3-diene
produces an allylcobalt(III) species.7 Homolytic cleavage of
allylcobalt(III) to an allyl radical followed by trapping with
chromium(II) gives allylchromium(III),6b,19 which adds to the
carbonyl compounds in a selective manner.2 Reduction of
cobalt(II) with chromium(II) regenerates the cobalt(I) spe-
cies.
Sch em e 1
Ack n ow led gm en t. We thank Prof. Tetsuo Toraya,
Department of Bioscience and Biotechnology, Faculty of
Engineering, Okayama University, for valuable sugges-
tions. This work was supported by a Grant-in-Aid for
Scientific Research on Priority Area No. 283 from the
Ministry of Education, Science, Sports and Culture, J apan.
We are tempted to assume the following mechanism for
the reaction (Scheme 1).17 Cobalt(I) species, B12s, derived
by the reduction of B12 with 2 equiv of chromium(II)
Su p p or tin g In for m a tion Ava ila ble: General procedure and
spectroscopic and analytical data of compounds in Table 1 (4
pages).
(17) Another possible mechanism is as follows: (1) insertion of a low-
valent cobalt to a carbon-hydrogen bond of an aldehyde; (2) hydroacyl-
ation;18 (3) successive reduction of a ketone. However, when we prepared
1-deuterio-3-phenylpropanal and used it in the reaction with 2,3-dimethyl-
1,3-butadiene, deuterium was found only at the carbon attached to a
hydroxyl group of the adduct 1. In addition, a ketone functionality remained
untouched during the reaction (Table 1, entry 4). These results argue against
the hydroacylation-reduction mechanism.
J O9814086
(18) Lenges, C. P.; Brookhart, M. J . Am. Chem. Soc. 1997, 119, 3165.
(19) Direct transmetalation of an allylic group from cobalt(III) with
chromium(III) could not be eliminated.8.