10220
J. Am. Chem. Soc. 2000, 122, 10220-10221
Scheme 1. Two-Step One-Pot Preparation of
Bicyclopentenones
One Pot Preparation of Bicyclopentenones from
Propargyl Malonates (and Propargylsulfonamides)
and Allylic Acetates by a Tandem Action of Catalysts
Nakcheol Jeong,* Seong Deok Seo, and Jin Young Shin
Department of Chemistry and DiVision of Chemistry and
Molecular Engineering, Korea UniVersity
1-5 ka Anamdong, Sungbukku, Seoul 136-701, Korea
ReceiVed May 23, 2000
One of the most remarkable features in living organisms is
the specific synthesis of numerous metabolites.1 A number of
enzymes are involved in the synthesis of a selected metabolite
and every enzyme shows high substrate specificity among many
structurally related intermediates. As a result, the whole sequence
of transformation could be carried out in one pot with high
efficiency. Mimicking of this feature with conventional chemical
catalysts would be a great interest among organic chemists. The
success of these manipulations would allow not only a conceptual
advance in the design of new processes, but also economically
useful processes, which will minimize the use of chemicals and
the production of waste, and the processing time.
Some relevant reports such as a domino reaction of specially
designed substrates with a single catalyst2 have appeared in the
literature. More closely related and interesting processes, for
example, a preparation of branched polyolefins from ethylene as
a sole feedstock with two catalysts3 and an olefin metathesis
followed by other transformations in one pot,4,5 have been reported
recently. Meantime, multienzymatic processes in vitro have also
been accomplished.6
Given the understanding of the state of the art and the need, it
is desirable to devise the one-pot multistep transformation, in
which the first step catalyzed by one catalyst creates the products
to be subjected to the second catalyst for the next step. And that
in turn sets up the third reaction, and so on.
In this context we choose the following multiple C-C bond-
forming transformations for a demonstration (Scheme 1). This
transformation includes two reactions; the first allylation generates
an enyne intermediate (3) via the Pd π-allyl complex7 from the
mixture of 1 and 2 and the following Pauson-Khand type reaction
(PKR hereafter) of the resultant enyne 3 yields a bicyclopentenone
(4).
could be facilitated by the electron-rich Pd(0) catalyst and the
second PKR needed a Lewis acidic catalyst.
Early attempts using various combinations of previously known
catalysts7,8 have failed. However, the progress of this study was
fortunately expedited by two recently published works: one is
Rh(I)-catalyzed PKR9 and another is Pd(dppb)-catalyzed allylic
substitution.10 Since these reactions are reported to be done in
rather mild and neutral conditions, they are expected to be
compatible in one vessel.
Preliminary experiments with each catalyst looked promising.
The allylation of a propargyl malonate (1-a-1) by palladium
catalyst with a variety of ligands in the presence of bis-
(trimethylsilyl)acetamide (BSA) proceeded nicely to give 3-a-1
in a variety of solvents such as CH2Cl2 or toluene (entries 1 and
5) as expected. No further reaction with the resultant enyne (3-
a-1) was observed even under CO pressure in several hours.
On the other hand, rhodium(I) alone, however, did not induce
an allylation or intermolecular PKR between 1-a-1 and allyl
acetate (2) at all cases (entries 6-9). But if the reaction mixture
was allowed to be under the same reaction condition for a
prolonged period (>20 h), a multitude of side products began to
appear.11
The tandem reaction was then examined with a mixture of
catalysts.12 It was observed that the efficiencies of the tandem
reaction were sensitive to the catalyst combinations and the
reaction conditions.
Since sodium propargyl malonate as a nucleophile in the
allylation was not compatible with the catalysts, it was better to
use 1-a-1 together with N,O-bis(trimethylsilyl)acetamide (BSA).
The allylation was also substantially influenced by the nature of
both ligands for the Pd(O) and Rh(I) counterparts. 1,4-Bis-
(diphenylphosphino)butane (dppb) worked well in general (entry
5). The Lewis acidity of Rh(I) seems to influence substantially
the allylation efficiency. While [RhCl(CO)2]2 (b-1) and [RhCl-
(CO)dppe] (b-3) were not compatible with Pd(dba)2/dppb so that
even the first allylation reaction was blocked, [RhCl(CO)(dppp)]2
(b-4) and [RhCl(CO)(dppb)]2 (generated in situ by mixing of b-2
and dppb)13 were compatible with the presumed Pd(dppb).14
Key to the success of this transformation would be the
identification of the right combinations of catalysts which are
compatible with each other because the first allylation reaction
(1) Nelson, D. L.; Cox, M. M. Lehninger Principles of Biochemistry, 3rd
ed.; Worth Publishers: New York, 2000.
(2) (a) Hall, N. Science 1994, 266, 32. (b) Tietze, L. F. Chem. ReV. 1996,
96, 115.
(3) (a) Komon, J. A. Z.; Bu, X.; Bazan, G. C. J. Am. Chem. Soc. 2000,
122, 1830. (b) Barnhart, R. W.; Bazan, G. C.; Mourney, T. J. Am. Chem.
Soc. 1998, 120, 1082. (c) Johnson, L. K.; Killian, C. M.; Brookhart, M. J.
Am. Chem. Soc. 1995, 117, 6414. (d) Pellechia, C.; Pappalardo, D.; Gruter,
G. J. Macromolecules 1999, 32, 4491.
(4) With Ti-mediated kinetic resolution; Morken, J. P.; Didiuk, M. T.;
Visser, M. S.; Hoveyda, A. H. J. Am. Chem. Soc. 1994, 116, 3123.
(5) With Heck reaction: Grigg, R.; Sridharan, V.; York, M. Tetrahedron
Lett. 1998, 39, 4139.
(8) (a) Geis, O.; Schmalz, H.-G. Angew. Chem., Int. Ed. Engl. 1998, 37,
911. (b) Chung, Y. K. Coord. Chem. Res. 1999, 188, 297.
(9) (a) Jeong, N.; Lee, S.; Sung, B. K. Organometallics 1998, 17, 3642.
(b) Jeong, N.; Sung, B. K.; Choi, Y. K. J. Am. Chem. Soc. 2000, 122, 6771.
(10) Nomura, N.; Tsurugi, K.; Okada, M. J. Am. Chem. Soc. 1999, 121,
7268.
(11) Refer to the gas-chromatogram in the Supporting Information for the
multicatalytic process and for a reaction with the same mixture by Pd(0) and
Rh(I), respectively.
(6) (a) Fessner, W.-D.; Walter, C. Angew. Chem., Int. Ed. Engl. 1992, 31,
614. (b) Eyrisch, O.; Fessner, W.-D. Angew. Chem., Int. Ed. Engl. 1995, 34,
1639. (c) Eyrisch, O.; Keller, M.; Fessner, W.-D. Tetrahedron Lett. 1994, 35,
9013. (d) Petersen, M.; Zannetti, M. T.; Fessner, W.-D. Top. Curr. Chem.
1997, 186, 87. (e) Zimmermann, F. T.; Schneider, A.; Schorken, U.; Sprenger,
G. A.; Fessner, W.-D. Tetrahedron: Asymmetry 1999, 10, 1643. (f) Gijsen,
H. J. M.; Wong, C.-H. J. Am. Chem. Soc. 1995, 117, 2947.
(7) (a) Tsuji, J. Transition Metal Reagents and Catalysts; John Wiley &
Sons, Ltd.: London, England, 2000. (b) Tsuji, J. Palladium Reagents and
Catalysts, InnoVations in Organic Synthesis; John Wiley: New York, 1995;
p 290.
(12) In typical experiments substrates 1-a-1 and 2 were added to a solution
of the mixture of catalysts a and/or b at ambient temperature. The reaction
mixture was evacuated and charged with CO (1 atm) and allowed to react at
room temperature for a couple of hours first and then, if there was no change,
heated at the appropriate temperature.
(13) Sanger, A. R. J. Chem. Soc., Dalton Trans. 1977, 120.
10.1021/ja001750b CCC: $19.00 © 2000 American Chemical Society
Published on Web 09/28/2000