Rea ction of Allylsila n es a n d Allylsta n n a n es w ith Alk yn es
Ca ta lyzed by Electr op h ilic La te Tr a n sition Meta l Ch lor id es
Carolina Ferna´ndez-Rivas,† Mar´ıa Me´ndez, Cristina Nieto-Oberhuber, and
Antonio M. Echavarren*
Departamento de Quı´mica Orga´nica, Universidad Auto´noma de Madrid,
Cantoblanco, 28049 Madrid, Spain
anton.echavarren@uam.es
Received April 11, 2002
The intramolecular reaction of allylsilanes and allylstannanes with alkynes proceeds catalytically
in the presence of Pt(II), Pd(II), Ru(II), and Au(III) chlorides. Although more limited, AgOTf also
catalyzes the cyclization. Usually, PtCl2 as the catalyst in methanol or acetone gives the best results.
The reaction proceeds by exo attack of the allyl nucleophile on the alkyne to form five- or six-
membered ring carbocycles. The reaction generally proceeds with anti stereoselectivity. However,
a terminally substituted trimethylsilyl derivative reacts by a syn-type addition. The intermediate
alkenylpalladium complex has been trapped with allyl chloride to form an allylated derivative with
an additional carbon-carbon bond.
In tr od u ction
at the cyclopropyl carbons labeled a and b of intermediate
II then presumably gives rise to the formation of five-
(III) or six-membered (IV) intermediates, which evolve
under catalytic conditions to afford carbo- or heterocycles
V or VI. Theoretical studies suggest that intermediates
similar to II are also involved in the intramolecular
reaction of furans with alkynes catalyzed by Pt(II).8
Alternatively, coordination of both functional groups of
the enyne to MXn may form VII, which undergoes an
oxidative metalacycloaddition to give metalacyclopentene
VIII.7b This metalacycle then evolves by â-hydride elimi-
nation to give cycloisomerization products IX and X.7b,9
The transition-metal-promoted cyclizations by intramo-
lecular attack of mild nucleophilic reagents such as
allylsilanes10 or allylstannanes11 (XI) onto alkynes has
been less explored.12,13 This reaction could proceed in a
concerted manner through XII, or via cyclopropylmetal-
carbene XIII,7b to form alkenylmetal complex XIV (Scheme
Metal-promoted carbocyclization reactions of R,ω-
enynes are of great interest due to the highly function-
alized carbo- and heterocycles that can be prepared.1 In
particular, electrophilic metal complexes or halides cata-
lyze a variety of cyclization reactions in which all atoms
included in the starting materials end up in the reaction
products.2-6 We have shown that coordination of PtCl2
to an enyne through the alkyne (I, Scheme 1) promotes
the intramolecular reaction of the alkene to form a
cyclopropyl Pt-carbene intermediate II (MXn ) PtCl2).7
Subsequent attack of the nucleophile (alcohol or water)
† Current address: PharmaMar, S.A., Tres Cantos, 28760 Madrid,
Spain.
(1) Reviews of metal-catalyzed carbocyclizations: (a) Ojima, I.;
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662. (b) Negishi, E.; Cope´ret, C.; Ma, S.; Liou, S.-Y.; Liu, F. Chem.
Rev. 1996, 96, 365-393. (c) Trost, B. M. Chem. Eur. J . 1998, 4, 2405-
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M.; Toste, D. F.; Pinkerton, A. B. Chem. Rev. 2001, 101, 2067-2096.
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1636-1638. (b) Trost. B. M.; Trost, M. K. Tetrahedron Lett. 1991, 32,
3647-3650. (c) Trost, B. M.; Trost, M. K. J . Am. Chem. Soc. 1991,
113, 3, 1850-1852. (d) Trost, B. M.; Chang, V. K. Synthesis 1993, 824-
832. (e) Trost, B. M.; Yanai, M.; Hoogsten, K. J . Am. Chem. Soc. 1993,
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Ed. Engl. 1993, 32, 1085-1087. (g) Trost, B. M.; Hashmi, A. S. K. J .
Am. Chem. Soc. 1994, 116, 2183-2814. (h) Trost, B. M.; Doherty, G.
A. J . Am. Chem. Soc. 2000, 122, 3801-3810.
(7) (a) Me´ndez, M.; Mun˜oz, M. P.; Echavarren, A. M. J . Am. Chem.
Soc. 2000, 122, 11549-11550. (b) Me´ndez, M.; Mun˜oz, M. P.; Nevado,
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(8) Mart´ın-Matute, B.; Ca´rdenas, D. J .; Echavarren, A. M. Angew.
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(9) (a) Trost, B. M.; Lautens, M.; Chan, C.; J ebaratnam, D. J .;
Mueller, T. J . Am. Chem. Soc. 1991, 113, 636, and references therein.
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Thomas, A. P. J . Am. Chem. Soc. 1999, 121, 6183. (c) Trost, B. M.;
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(3) (a) Chatani, N.; Morimoto, T.; Muto, T.; Murai, S. J . Am. Chem.
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(10) (a) Patai, S., Rappoport, Z., Eds. The Chemistry of Organic
Silicon Compounds; Wiley: Chichester, U.K., 1998; Part 2. (b) Fleming,
I.; Barbero, A.; Walter, D. Chem. Rev. 1997, 97, 2063-2192.
(11) (a) Davies, A. G. Organotin Chemistry; VCH: Weinheim,
Germany, 1997. (b) Synthesis of allylstannanes from allyl carboxylates
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117, 560-561. (b) Castan˜o, A. M.; Persson, B. A.; Ba¨ckvall, J .-E. Chem.
Eur. J . 1997, 3, 482-490.
(13) For a review, see: Me´ndez, M.; Echavarren, A. M. Eur. J . Org.
Chem. 2002, 15-28.
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10.1021/jo025812n CCC: $22.00 © 2002 American Chemical Society
Published on Web 06/18/2002
J . Org. Chem. 2002, 67, 5197-5201
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