C O M M U N I C A T I O N S
Table 2. Rhodium-Catalyzed [2 + 1] Cycloadditiona
ethyl diazoacetate (9) with 2a, while the Rh(I)+/bisphosphine
complex did catalyze the cycloaddition (eq 3):
The formation of 3aa through intermediates F, (E)-G, and I might
also be excluded as a result of the stable Rh-O chelation in (Z)-G
and the absence of possible ꢀ-hydride elimination product 8aa. On
the other hand, the [2 + 2] cycloaddition of intermediate D with
5a furnishes rhodacyclobutane J. Subsequent reductive elimination
yields 6aa. Trans chelation of the ester and amide carbonyl groups
to the cationic rhodium in intermediate J might account for the
observed perfect diastereoselectivity.19,20 Chelation of the alkenyl-
acetate carbonyl group might be excluded because of the equilibra-
tion between intermediates C and D.13a,b
a [Rh(cod)2]SbF6 (0.025 mmol), 1a-h (0.50 mmol), 5a-c (1.00
mmol), and CH2Cl2 (1.0 mL) were used. Cited yields are of isolated
products. b Catalyst: 10 mol %.
Future work will focus on further investigations into mechanistic
insights and applications in organic synthesis.
Acknowledgment. This work was partially supported by Grants-
in-Aid for Scientific Research (19028015, 20675002, and 21 ·906)
from MEXT, Japan. We thank Umicore for generous support in
supplying rhodium complexes.
Scheme 1
Supporting Information Available: Experimental procedures,
compound characterization data, optimization of reaction conditions,
and X-ray crystallographic data (CIF). This material is available free
References
(1) For selected recent reviews, see: (a) Pellissier, H. Tetrahedron 2008, 64,
7041. (b) Davies, H. M. L.; Walji, A. M. In Modern Rhodium-Catalyzed
Organic Reactions; Evans, P. A., Tsuji, J., Eds.; Wiley-VCH: Weinheim,
Germany, 2005; p 301. (c) Doyle, M. P. In Modern Rhodium-Catalyzed
Organic Reactions; Evans, P. A., Tsuji, J., Eds.; Wiley-VCH: Weinheim,
Germany, 2005; p 341. (d) Wu, Y.-T.; Kurahashi, T.; de Meijere, A. J.
Organomet. Chem. 2005, 690, 5900.
(2) (a) Miller, J. A.; Jin, W.; Nguyen, S. T. Angew. Chem., Int. Ed. 2002, 41,
2953. (b) Miller, J. A.; Gross, B. A.; Zhuravel, M. A.; Jin, W.; Nguyen,
S. T. Angew. Chem., Int. Ed. 2005, 44, 3885.
(3) (a) Chen, Y.; Ruppel, J. V.; Zhang, X. P. J. Am. Chem. Soc. 2007, 129,
12074. (b) Zhu, S.; Perman, J. A.; Zhang, X. P. Angew. Chem., Int. Ed.
2008, 47, 8460. (c) Zhu, S.; Ruppel, J. V.; Lu, H.; Wojtas, L.; Zhang,
X. P. J. Am. Chem. Soc. 2008, 130, 5042.
(4) del Amo, J. C.; Mancheno, M. J.; Gomez-Gallego, M.; Sierra, M. A.
Organometallics 2004, 23, 5021.
(5) (a) Barluenga, J.; Vicente, R.; Lopez, L. A.; Rubio, E.; Tomas, M.; Alvarez-
Rua, C. J. Am. Chem. Soc. 2004, 126, 470. (b) Barluenga, J.; Vicente, R.;
Lopez, L. A.; Tomas, M. J. Organomet. Chem. 2006, 691, 5642. (c)
Barluenga, J.; Vicente, R.; Lopez, L. A.; Tomas, M. J. Am. Chem. Soc.
2006, 128, 7050.
N-methyl-N-phenyl-, and N,N-diphenylacrylamides reacted with 1a
at 40 °C to give cyclopropanes 6aa-ac in good yields with perfect
diastereoselectivity. The cyclopropanation of acrylamide 5a with
a variety of tertiary propargyl esters proceeded to afford cyclopro-
panes 6ba-ea and 6ga in good yields as single diastereomers, while
exo-alkylidenecyclohexane 6fa was generated in low yield and a
secondary propargyl ester failed to react with 5a.
A plausible mechanism for the formation of 3aa and 6aa is
shown in Scheme 1. A metalla-Diels-Alder reaction5,17 of alk-
enylcarbene D with 2a furnishes rhodacycle E, and subsequent
reductive elimination yields 3aa. According to the proposed
mechanism of the [3 + 2] cycloaddition of diazoacetates with
alkynes to give furans,18 the formation of furan 7aa through
intermediates F, (Z)-G, and H would also be possible. The metalla-
Diels-Alder reaction rather than the [2 + 2] cycloaddition of
Rh(I)+/cod alkenylcarbene D with 2a proceeds preferentially under
the present reaction conditions, which might account for the
observed chemoselective formation of 3aa rather than 7aa. Indeed,
the Rh(I)+/cod complexes failed to catalyze the cycloaddition of
(6) (a) Rautenstrauch, V. J. Org. Chem. 1984, 49, 950. (b) Rautenstrauch, V.
Tetrahedron Lett. 1984, 25, 3845.
(7) (a) Miki, K.; Ohe, K.; Uemura, S. Tetrahedron Lett. 2003, 44, 2019. (b)
Miki, K.; Ohe, K.; Uemura, S. J. Org. Chem. 2003, 68, 8505. (d) Tenaglia,
A.; Marc, S. J. Org. Chem. 2006, 71, 3569.
(8) (a) Johansson, M. J.; Gorin, D. J.; Staben, S. T.; Toste, F. D. J. Am. Chem.
Soc. 2005, 127, 18002. (b) Gorin, D. J.; Dube, P.; Toste, F. D. J. Am.
Chem. Soc. 2006, 128, 14480. (c) Gorin, D. J.; Watson, I. D. G.; Toste,
F. D. J. Am. Chem. Soc. 2008, 130, 3736. For other related cycloadditions,
see: (d) Shapiro, N. D.; Toste, F. D. J. Am. Chem. Soc. 2008, 130, 9244.
(e) Shapiro, N. D.; Shi, Y.; Toste, F. D. J. Am. Chem. Soc. 2009, 131,
11654.
(9) For selected recent reviews, see: (a) Gorin, D. J.; Toste, F. D. Nature 2007,
446, 395. (b) Kusama, H.; Iwasawa, N. Chem. Lett. 2006, 35, 1082. (c)
Miki, K.; Uemura, S.; Ohe, K. Chem. Lett. 2005, 34, 1068.
(10) For selected recent examples, see: (a) Lian, Y.; Davies, H. M. L. J. Am.
Chem. Soc. 2010, 132, 440. (b) Davies, H. M. L.; Xiang, B.; Kong, N.;
Stafford, D. G. J. Am. Chem. Soc. 2001, 123, 7461.
(11) Shibata, Y.; Noguchi, K.; Hirano, M.; Tanaka, K. Org. Lett. 2008, 10, 2825.
(12) Tanaka, K.; Okazaki, E.; Shibata, Y. J. Am. Chem. Soc. 2009, 131, 10822.
(13) (a) Prasad, B. A. B.; Yoshimoto, F. K.; Sarpong, R. J. Am. Chem. Soc.
2005, 127, 12468. (b) Pujanauski, B. G.; Prasad, B. A. B.; Sarpong, R.
J. Am. Chem. Soc. 2006, 128, 6786. (c) Zhang, G.; Zhang, L. J. Am. Chem.
Soc. 2008, 130, 12598.
(14) Ru(II), Pd(II), Pt(II), and Au(I) complexes failed to catalyze the reaction.
9
J. AM. CHEM. SOC. VOL. 132, NO. 23, 2010 7897