Communications
84; b) M. T. Crimmins in Comprehensive Organic Synthesis,
Vol. 5 (Eds.: B. M. Trost, I. Fleming), Pergamon, Oxford, 1991,
pp. 123 – 150.
Table 2: Rhodium(i)-catalyzed two-carbon-atom ring expansion of 5 with
2a.[a]
Entry
Substrate 5
Product 6
Yield [%][b]
[4] For 1,2-addition of aryl rhodium(i) to an internal alkyne, see:
a) T. Hayashi, K. Inoue, N. Taniguchi, M. Ogasawara, J. Am.
Chem. Soc. 2001, 123, 9918 – 9919; b) M. Lautens, M. Yoshida,
Org. Lett. 2002, 4, 123 – 125.
1
5b
6b
51
[5] An analogous 1,2-addition to dimethyl 2-(but-2-ynyl)-2-methyl-
malonate, which bears a methoxycarbonyl groupinstead of the
benzoyl groupin 1a, proceeded much more slowly: T. Miura, M.
Shimada, M. Murakami, J. Am. Chem. Soc. 2005, 127, 1094 –
1095.
[6] For intramolecular addition of an organorhodium(i) species to a
ketone carbonyl group, see: a) A. Takezawa, K. Yamaguchi, T.
Ohmura, Y. Yamamoto, N. Miyaura, Synlett 2002, 1733 – 1735;
b) D. F. Cauble, J. D. Gipson, M. J. Krische, J. Am. Chem. Soc.
2003, 125, 1110 – 1111; c) R. Shintani, K. Okamoto, Y. Otomaru,
K. Ueyama, T. Hayashi, J. Am. Chem. Soc. 2005, 127, 54 – 55;
d) T. Matsuda, M. Makino, M. Murakami, Angew. Chem. 2005,
117, 4684 – 4687; Angew. Chem. Int. Ed. 2005, 44, 4608 – 4611.
[7] When the 1H NMR spectrum of the crude reaction mixture was
measured prior to chromatographic purification, we observed
about 50% of 3 and approximately 20% of 4aa.
2
3
5c
5d
6c
6d
49
58
4
5e
6e
54[c]
[8] Ring opening of a cyclobutanol skeleton by a retro-aldol
reaction occurred much more readily than b-carbon elimination
of rhodium(i) cyclobutanolates: a) T. Matsuda, M. Makino, M.
Murakami, Bull. Chem. Soc. Jpn. 2005, 78, 1528 – 1533; see also
reference [6d]; for a review on b-carbon elimination from
palladium(ii) cyclobutanolate, see: b) T. Nishimura, S. Uemura,
Synlett 2004, 201 – 216.
5
6
5 f
6 f
57
66
5g
6g
[9] For examples of photochemical acyl 1,3-migration of b,g-
unsaturated cyclic ketones, see: a) H. Suginome, M. Takemura,
N. Shimoyama, K. Orito, J. Chem. Soc. Perkin Trans. 1 1991,
2721 – 2723; b) J. Shin, W. Fenical, J. Org. Chem. 1991, 56, 1227 –
1233.
[10] Although o-tolylboronic acid underwent 1,2-addition to the
carbon–carbon triple bond, the resultant alkenyl rhodium(i)
intermediate was not reactive enough for the addition to the
benzoyl group.
[a] Reaction conditions: 5 (0.2 mmol), 2 (1.0 mmol), [{Rh(OH)(cod)}2]
(0.05 equiv of Rh), room temperature, dioxane/H2O (2.0 mL/20 mL);
then treatment with aqueous NH4Cl. [b] Yields of isolated products.
[c] 1008C
[11] A 1,2-adduct formed by addition of a phenylrhodium species
with the opposite regiochemistry was obtained in 47%.
[12] For examples of ring expansion through intramolecular carbonyl
addition/ring opening, see: a) C.-J. Li, D.-L. Chen, Y.-Q. Lu, J. X.
Haberman, J. T. Mague, J. Am. Chem. Soc. 1996, 118, 4216 –
4217; b) A. E. Imai, Y. Sato, M. Nishida, M. Mori, J. Am. Chem.
Soc. 1999, 121, 1217 – 1225; c) U. K. Tambar, B. M. Stoltz, J. Am.
Chem. Soc. 2005, 127, 5340 – 5341; for a review, see: d) P. M.
Wovkulich in Comprehensive Organic Synthesis, Vol. 1 (Eds.:
B. M. Trost, I. Fleming), Pergamon, Oxford, 1991, pp. 892 – 897.
[13] For ring expansion through photochemical [2+2] cycloaddition/
ring opening, see: J. D. Winkler, C. M. Bowen, F. Liotta, Chem.
Rev. 1995, 95, 2003 – 2020, and references therein.
that are otherwise difficult to form were constructed in a
simple operation from readily available substrates.
Received: July 28, 2005
Published online: October 31, 2005
Keywords: acyl migration · boron · cyclizations · rhodium ·
.
ring expansion
[1] For reviews, see: a) K. Fagnou, M. Lautens, Chem. Rev. 2003,
103, 169 – 196; b) T. Hayashi, K. Yamasaki, Chem. Rev. 2003,
103, 2829 – 2844.
[14] The major by-products were the simple 1,2-adducts formed by
addition to the carbon–carbon triple bond.
[2] T. Miura, M. Shimada, M. Murakami, Synlett 2005, 667 – 669.
[3] a) J. E. Baldwin in Comprehensive Organic Synthesis, Vol. 5
(Eds.: B. M. Trost, I. Fleming), Pergamon, Oxford, 1991, p p . 63 –
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2005, 44, 7598 –7600