Nickel-catalyzed borylative ring-opening reaction of vinylcyclopropanes with bis(pinacolato)diboron yielding allylic boronates

Article abstract of DOI:10.1021/ol801982d

(Chemical Equation Presented) Vinylcyclopropanes bearing one or two electron-withdrawing groups on the cyclopropane ring undergo nickel-catalyzed borylative ring opening with bis(pinacolato)diboron to yield allylic boronates. The reaction proceeded with h

Full text of DOI:10.1021/ol801982d

ORGANIC
LETTERS
2008
Vol. 10, No. 20
4677-4679
Nickel-Catalyzed Borylative
Ring-Opening Reaction of
Vinylcyclopropanes with
Bis(pinacolato)diboron Yielding Allylic
Boronates
Yuto Sumida, Hideki Yorimitsu,* and Koichiro Oshima*
Department of Material Chemistry, Graduate School of Engineering, Kyoto UniVersity,
Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
yori@orgrxn.mbox.media.kyoto-u.ac.jp; oshima@orgrxn.mbox.media.kyoto-u.ac.jp
Received August 25, 2008
ABSTRACT
Vinylcyclopropanes bearing one or two electron-withdrawing groups on the cyclopropane ring undergo nickel-catalyzed borylative ring opening
with bis(pinacolato)diboron to yield allylic boronates. The reaction proceeded with high E selectivity.
Allylic boron reagents are among the most important reagents
in organic synthesis.1 Modern organic synthesis requires
more complex and functionalized allylic boron reagents than
ever for synthesis of a wider variety of biologically intriguing
compounds. However, functionalized allylic boron reagents
are not always easy to synthesize, and development of new
methods for the synthesis of allylic boron reagents is
expected.2,3 Here we report nickel-catalyzed borylative ring-
opening reactions of vinylcyclopropanes with bis(pinacola-
to)diboron which provide allylic boron reagents.4-6
Treatment of bis(ethoxycarbonyl)-substituted vinylcyclo-
propane 1a with bis(pinacolato)diboron (2) in the presence
of potassium phosphate trihydrate and catalytic amounts of
Ni(cod)2 and tricyclopentylphosphine in toluene/methanol
afforded allylic boronate 3a (Table 1, entry 1).7 The reaction
was high yielding and proceeded with high E selectivity.
Analogous to the previous reports on nickel-catalyzed
(3) Recent selected examples: (a) Ito, H.; Ito, S.; Sasaki, Y.; Matsuura,
K.; Sawamura, M. J. Am. Chem. Soc. 2007, 129, 14856–14857. (b) Shimizu,
M.; Shimono, K.; Hiyama, T. Chem. Lett. 2006, 35, 838–839. (c) Murata,
M.; Watanabe, S.; Masuda, Y. Tetrahedron Lett. 2000, 41, 5877–5880. (d)
Takahashi, K.; Ishiyama, T.; Miyaura, N. Chem. Lett. 2000, 29, 982–983.
(e) Kabalka, G. W.; Venkataiah, B.; Dong, G. J. Org. Chem. 2004, 69,
5807–5809. (f) Ishiyama, T.; Ahiko, T.; Miyaura, N. Tetrahedron Lett. 1996,
37, 6889–6892. (g) Ramachandran, P. V.; Pratihar, D.; Biswas, D.;
Srivastava, A.; Reddy, M. V. R. Org. Lett. 2004, 6, 481–484. (h) Dutheuil,
G.; Selander, N.; Szabo´, K. J.; Aggarwal, V. K. Synthesis 2008, 2293–
2297. (i) Selander, N.; Kipke, A.; Sebelius, S.; Szabo´, K. J. J. Am. Chem.
Soc. 2007, 129, 13723–13731.
(1) Reviews: (a) Yamamoto, Y.; Asao, N. Chem. ReV. 1993, 93, 2207–
2293. (b) Denmark, S. E.; Fu, J. P. Chem. ReV. 2003, 103, 2763–2793. (c)
Yamamoto, Y.; Miyaura, N. J. Synth. Org. Chem. Jpn. 2008, 66, 194–204.
(d) Kennedy, J. W. J.; Hall, D. G. Angew. Chem., Int. Ed. 2003, 42, 4732–
4739. (e) Hall, D. G. Synlett 2007, 1644–1655.
(2) Reviews: (a) Hall, D. G. Pure Appl. Chem. 2008, 80, 913–927. (b)
Ito, H.; Ito, S.; Sasaki, Y.; Matsuura, K.; Sawamura, M. Pure Appl. Chem.
2008, 80, 1039–1045. (c) Ishiyama, T.; Miyaura, N. Chem. Rec. 2004, 3,
271–280. (d) Darses, S.; Genet, J. P. Chem. ReV. 2008, 108, 288–325. (e)
Pietruszka, J.; Schone, N.; Frey, W. G.; Grundl, L. Chem.sEur. J. 2008,
14, 5178–5197. (f) Knochel, P.; Ila, H.; Korn, T. J.; Baron, O. In Handbook
of Functionalized Organometallics; Knochel, P., Ed.;Wiley-VCH: Wein-
(4) Palladium pincer complexes can catalyze similar transformations:
(a) Sebelius, S.; Olsson, V. J.; Szabo´, K. J. J. Am. Chem. Soc. 2005, 127,
10478–10479. (b) Sebelius, S.; Olsson, V. J.; Wallner, O. A.; Szabo´, K. J.
J. Am. Chem. Soc. 2006, 128, 8150–8151. (c) Selander, N.; Szabo´, K. J.
Chem. Commun. 2008, 3420–3422.
heim, Germany, 2005; Chapter 3.5
.
10.1021/ol801982d CCC: $40.75
Published on Web 09/23/2008
2008 American Chemical Society

Vinylcyclopropane 1f having only one tert-butoxycarbonyl
group at the cis position underwent efficient borylative ring
opening (entry 6). In contrast, the nickel-catalyzed reaction
of 1g, the trans isomer of 1f, led to the formation of 3f in
only 44% yield, in addition to a mixture of unidentified
byproducts (entry 7). These results are informative in
considering the reaction mechanism (vide infra).
Table 1. Scope of Vinylcyclopropanes
Cyclopropanes having a substituted vinyl group also
participated in the borylation reaction (Scheme 1). Isopro-
entry
E1
E2
1
x
3
yield /%a
E/Z
1
2
3
4
5
6
7
CO2Et
CO2Et
1a
5
2
3a
3b
84 (98)
73 (80)
66 (84)
57 (75)
(20)b
94:6
91:9
95:5
80:20
c
CO2Me CO2Me 1b
t
t
CO2 Bu CO2 Bu 1c
7.5 3c
2
2
5
10
Scheme 1. Nickel-Catalyzed Reactions of Isopropenyl- and
CO2Et
Ac
Ac
Ac
H
1d
1e
3d
3e
3f
(1-Propenyl)cyclopropanes with 2 (E ) COOEt)
CO2 Bu
1fd
85
44
91:9
85:15
t
t
H
CO2 Bu 1g
3f
a Isolated yields. NMR yields are in parentheses. The lower isolated
yields would be attributed to partial decomposition of 3 during silica gel
column purification. b Furan derivative 4 was obtained in 6% yield.
c Not determined. d A mixture of cis and trans isomers (1f/1g ) 84:16)
was used.
reactions with boron reagents,6c,8 the reaction required base,
which would activate boron species. The addition of metha-
nol was essential for smooth protonation of the boron
enolate6c,8c (vide infra).
As the size of electron-withdrawing groups on the cyclo-
propane ring become larger, the reactions required higher
catalyst loadings to attain high yields and the E/Z ratios were
slightly improved (entries 1-3). Acetyl-substituted 1d
reacted with 2 to provide 3d with moderate stereoselectivity
(entry 4). Diacetyl-substituted vinylcyclopropane 1e was
converted to desired product 3e in only 20% yield, along
with furan derivative 4 as a byproduct (entry 5).5f
penylcyclopropane 1h underwent the reaction with low
stereoselectivity (eq 1). When (1-propenyl)cyclopropane 1i
was employed, a mixture of regioisomers 3i and 3j was
obtained with high E selectivity (eq 2).
(5) Nickel-catalyzed reactions of vinylcyclopropanes: (a) Murakami, M.;
Nishida, S. Chem. Lett. 1979, 8, 927–930. (b) Hiroi, K.; Arinaga, Y.; Ogino,
T. Chem. Lett. 1992, 21, 2329–2332. (c) Ryu, I.; Ikura, K.; Tamura, Y.;
Maenaka, J.; Ogawa, A.; Sonoda, N. Synlett 1994, 941–942. (d) Suginome,
M.; Matsuda, T.; Yoshimoto, T.; Ito, Y. Organometallics 2002, 21, 1537–
1539. (e) Zuo, G.; Louie, J. J. Am. Chem. Soc. 2005, 127, 5798–5799. (f)
Bowman, R. K.; Johnson, J. S. Org. Lett. 2006, 8, 573–576. (g) Ikeda, S.;
Obara, H.; Tsuchida, E.; Shirai, N.; Odashima, K. Organometallics 2008,
On the basis of these results as well as our previous
reports,6c,8 we assume the reaction mechanism as follows
(Scheme 2). Cyclopropane 1a is activated by Lewis acidic
2, and the activated 1a undergoes oxidative addition to a
27, 1645–1648
.
(6) Nickel-catalyzed reactions of diborons are rare: (a) Beletskaya, I.;
Moberg, C. Chem. ReV. 1999, 99, 3435–3462. (b) Yu, C.-M.; Youn, J.;
Yoon, S.-K.; Hong, Y.-T. Org. Lett. 2005, 7, 4507–4510. (c) Hirano, K.;
Scheme 2. Plausible Reaction Mechanism
Yorimitsu, H.; Oshima, K. Org. Lett. 2007, 9, 5031–5033
.
(7) General procedure: Ni(cod)2 (2.8 mg, 0.010 mmol) and K3PO4•3H2O
(120 mg, 0.45 mmol) were placed in a 20 mL reaction flask under argon.
Toluene (1.0 mL) and tricyclopentylphosphine (0.50 M toluene solution,
0.06 mL, 0.03 mmol) were added. The resulting suspension was stirred for
10 min at 0 °C. Vinylcyclopropane 1a (42 mg, 0.20 mmol) and bis(pina-
colato)diboron (2, 76 mg, 0.30 mmol) in toluene (2.0 mL) were then added.
Methanol (0.10 mL) was added, and the mixture was allowed to warm to
25 °C and stirred for 10 h. The reaction was quenched with water (3 mL).
Extraction followed by concentration in vacuo afforded an oil. The crude
oil was purified on silica gel (Kanto Chemical, silica gel 60N, hexane/
ethyl acetate ) 10:1) by using a dry ice/acetone-jacketed chromatographic
column to yield 3a (57 mg, 0.17 mmol, E/Z ) 94:6) in 84% yield.
(8) (a) Hirano, K.; Yorimitsu, H.; Oshima, K. Org. Lett. 2005, 7, 4689–
4691. (b) Hirano, K.; Yorimitsu, H.; Oshima, K. AdV. Synth. Catal. 2006,
348, 1543–1546. (c) Hirano, K.; Yorimitsu, H.; Oshima, K. Org. Lett. 2007,
9, 1541–1544
.
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Org. Lett., Vol. 10, No. 20, 2008

Ni(0) complex6c,8-10 to afford π-allyl(oxa-π-allyl)nickel11
5. Transmetalation then occurs to yield π-allylnickel 6
bearing a boron enolate moiety. Reductive elimination
provides the boron enolate of 3a, which is protonated in situ
to afford 3a, with concomitant formation of the initial Ni(0)
complex.
Finally, the reaction of allylic boronate 3a with benzal-
dehyde was examined (Scheme 4). Isolated 3a reacted with
Scheme 4. Copper-Catalyzed Reaction of 3a with Benzaldehyde
The difference of the reactivities of 1f and 1g suggests
that oxidative addition of 1f would be more favorable than
that of 1g (Scheme 3). The cis configuration of 1f would
Scheme 3. Plausible Detailed Mechanism of Oxidative Addition
benzaldehyde smoothly in the presence of 10 mol % of
1e,13
Cu(OTf)2
in toluene to afford the corresponding ho-
moallyl alcohol 9 in 91% yield with high anti selectivity.
Notably, one-pot sequential borylative ring-opening/allylation
reactions also provided 9 in high yield with similar diaste-
reoselectivity.
In summary, we have found a new catalytic activity of
nickel, which allows for synthesis of functionalized allylic
boronates of synthetic use.
allow for bidentate coordination to nickel to form 7f, which
would undergo smooth oxidative addition, yielding 5f directly
or via oxanickelacyclooctadiene 8f. Similarly, 1g would be
transformed to 7g. In contrast to the case of 7f, the
subsequent oxidative addition that yields 5f directly or
oxanickelacyclohexene 8g11,12 would be slow, thereby
competing with side reactions.
Acknowledgment. This work was supported by Grants-
in-Aid for Scientific Research and Global COE Research
Programs from JSPS.
Supporting Information Available: Characterization data
of the products. This material is available free of charge via
the Internet at http://pubs.acs.org.
(9) Johnson, J. R.; Tully, P. S.; Mackenzie, P. B.; Sabat, M. J. Am.
Chem. Soc. 1991, 113, 6172–6177
(10) In the absence of 2, treatment of 1a under the nickel catalysis
resulted in no reactions.
.
OL801982D
(11) Ogoshi, S.; Nagata, M.; Kurosawa, H. J. Am. Chem. Soc. 2006,
128, 5350–5351.
(12) (a) Liu, L.; Montgomery, J. J. Am. Chem. Soc. 2006, 128, 5348–
(13) Ramachandran, P. V.; Pratihar, D.; Biswas, D. Org. Lett. 2006, 8,
3877–3879.
5349. (b) Liu, L.; Montgomery, J. Org. Lett. 2007, 9, 3885–3887
.
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