Catalyzed cyclization of α,ω-dienes: A versatile protocol for the synthesis of functionalized carbocyclic and heterocyclic compounds [18]

Full text of DOI:10.1021/ja9738788

J. Am. Chem. Soc. 1998, 120, 8007-8008
Scheme 1. Metal-Catalyzed Eneyne Cyclization
Protocol for the Synthesis of Functionalized
Carbocyclic and Heterocyclic Compounds
8007
Catalyzed Cyclization of r,ω-Dienes: A Versatile
Branko Radetich and T. V. RajanBabu*
Department of Chemistry, The Ohio State UniVersity
Columbus, Ohio 43210
ReceiVed NoVember 12, 1997
Unactivated olefins and acetylenes have long been recognized
as latent functional groups compatible with many traditional
methods of C-C bond-forming reactions that use nucleophilic
and electrophilic reagents.1 Since activation of these function-
alities for further reactions is best carried out with transition metal
reagents, advantages associated with such a process can be brought
to bear on the subsequent chemistry even at late stages in a
synthesis.2 In this context, two of the most important attributes
relevant to synthetic efficiency are the potential for developing
catalytic processes and ligand modification for control of product
stereochemistry. One reaction that has received considerable
attention is cyclization of eneynes mediated by low valent Zr,
Ti, and Pd.3-5 For the Pd-catalyzed reaction, two principal
mechanistic possibilities have been advanced (Scheme 1), (a)
involvement of a palladacycle or (b) in situ formation of a [Ln-
Pd-H]+ (L ) ligand) followed by hydropalladation and subse-
quent carbapalladation. Ligand-dependent formation of stereo-
and regioisomers4b as well as an example6 of enantioselective
catalysis of eneyne cycloisomerization have been recorded.
In contrast, very little attention7 has been paid to the corre-
sponding Ni or Pd-catalyzed cyclization of R,ω-dienes, even
though the availability of starting materials and the diminished
Lewis acidity of these metals (vis-a´-vis early transition metals)
should make this process a very attractive one for development
of highly catalytic reactions.8 This is especially true for substrates
that contain heteroatoms such as O, N, and S, where the use of
near-stoichiometric amounts of Ti or Zr catalyst in addition to
several equivalents of trapping/reducing agents is routine.9-11
Recently we have been interested in the applications of well-
defined Pd(2+) and Ni(2+) monohydrides olefins. For example,
we recently reported a new procedure for asymmetric het-
Scheme 2. [Ni-H]+-Mediated Hydrovinylation of Vinylarenes
Scheme 3. Intramolecular Hydrovinylation of R,ω-Dienes
erodimerization of ethylene and vinylarenes (Scheme 2).12 Here
we report the first examples of an intramolecular version of this
reaction.13
When a cold CH2Cl2 solution of di-O-methyl diallylmalonate
(1) is treated with 0.05 equiv of Ni catalyst prepared from [Ni-
(allyl)Br]2, tri-4-methoxyphenylphosphine, and AgOTf, excellent
conversion of starting material to a methylenecyclopentane 2
ensues (Scheme 3).14 The cyclization reaction can be carried out
with [Pd(allyl)Cl]2 dimer in place of the corresponding Ni salt
(Table 1, entry 2). Not surprisingly, the palladium-catalyzed
reactions are slower and varying amounts of methylenecyclopen-
tane product 2 and an isomer 3, in which the double bond has
undergone migration to the endocyclic position, are produced in
91% isolated yield. With regard to functional group compatibility
of the present method, it is important to point out that Cp*2YMe-
(THF) failed to effect cyclization reaction of this substrate.7e
Likewise, other methods based on Cp2Zr,7d,g,9,11 and Cp2ScH7c are
also likely to be incompatible with this and similar substrates
with ester groups. Note that the products obtained are similar to
those from a Pd-catalyzed reductiVe cyclization of eneynes in the
presence of a polymeric silicon hydride.4b
(1) For recent reviews see: Tamao, K.; Kobayashi, K.; Ito, Y. Synlett 1992,
539. Trost, B. M. Angew. Chem., Int. Ed. Engl. 1995, 34, 259. Ojima, I.;
Tzamarioudaki, M.; Li, Z.; Donovan, R. J. Chem. ReV. 1996, 96, 635. Lautens,
M.; Klute, W.; Tam, W. Chem. ReV. 1996, 96, 49.
(2) For representative examples from recent literature, see: Wender, P.
A.; Rice, K. D.; Schnute, M. E. J. Am. Chem. Soc. 1997, 119, 7897. Uesaka,
N.; Saitoh, F.; Mori, M.; Shibasaki, M.; Okamura, K.; Date, T. J. Org. Chem.
1994, 59, 5633. Borer, B. C.; Deerenberg, S.; Biera¨ugel, H.; Pandit, U. K.
Tetrahedron Lett. 1994, 35, 3191 Trost, B. M.; Dumas, J.; Villa, M. J. Am.
Chem. Soc. 1992, 114, 9836.
Further scope and limitations of the reaction are illustrated in
Table 1 with a carefully chosen list of other dienes with sensitive
functional groups and heteroatoms. Typically, a number of
substituted arylphosphine ligands with both [Pd(allyl)Cl)]2 and
[Ni(allyl)Br)]2 were scouted for each reaction. In general,
monosubstituted olefins gave the best results, even though under
(3) For a review, see: Waymouth, R. M.; Knight, K. S. CHEMTECH,
April 1995; p. 15. Stoichiometric reactions: RajanBabu, T. V.; Nugent, W.
A.; Taber, D. F.; Fagan, P. J. J. Am. Chem. Soc. 1988, 110, 7128. Negishi,
E.-i.; Holmes, S. J.; Tour, J. M.; Miller, J. A.; Cederbaum, F. E.; Swanson,
D. R.; Takahashi, T. J. Am. Chem. Soc. 1989, 111, 3336. Catalytic versions:
Berk, S. C.; Grossman, R. B.; Buchwald, S. L. J. Am. Chem. Soc. 1993, 115,
4912 (using Cp2Ti). Zhang, M.; Buchwald, S. L. J. Org. Chem. 1996, 61,
4498 (using Ni(COD)2).
(8) For example, see: LnNi+-H-catalyzed dimerization of olefins, Wilke,
G. Angew. Chem., Int. Ed. Engl. 1988, 27, 185.
(9) Shaughnessy, K. H.; Waymouth, R. M. J. Am. Chem. Soc. 1995, 117,
7, 5873.
(10) For the use of an organoyttrium reagent in sequential cyclization/
silylation see: Molander, G. A.; Nichols, P. J. J Am. Chem. Soc. 1995, 117,
4415.
(11) Yamaura, Y.; Hyakutake, M.; Mori, M. J. Am. Chem. Soc. 1997, 119,
9, 7615.
(12) Nomura, N.; Jin, J.; Park, H.; RajanBabu, T. V. J. Am. Chem. Soc.
1998, 120, 459. See also ref 8.
(4) (a) Trost, B. M. Acc. Chem. Res. 1990, 23, 34. (b) Trost, B. M.; Rise,
F. J. Am. Chem. Soc. 1987, 109, 3161.
(5) Negishi, E.-i.; Cope´ret, C.; Ma, S.; Liou, S.-Y.; Liu, F. Chem. ReV.
1996, 96, 365.
(6) Trost, B. M.; Czeskis, B. A. Tetrahedron Lett. 1994, 35, 211.
(7) For early transition metal-mediated processes, (i) stoichiometric reac-
tions: (a) Nugent, W. A.; Taber, D. F. J. Am. Chem. Soc. 1989, 111, 1, 6435.
(b) Rousset, C. J.; Swanson, D. R.; Lamaty, F.; Negishi, E.-i. Tetrahedron
Lett. 1989, 30, 5105. (ii) Catalytic proceses: (c) Piers, W. E.; Shapiro, P. J.;
Bunel, E. E.; Bercaw, J. E. Synlett 1990, 74. (d) Knight, K. S.; Waymouth,
R. M. J. Am. Chem. Soc. 1991, 113, 6268. (e) Molander, G. A.; Hoberg, J. O.
J. Am. Chem. Soc. 1992, 114, 3123. (f) Negishi, E.-i. Takahashi, T. Acc. Chem.
Res. 1994, 27, 124. (g) Dzhemilev, U. M. Tetrahedron 1995, 51, 4333. (h)
Christoffers, J.; Bergman, R. G. J. Am. Chem. Soc. 1996, 118, 4715. (i) Thiele,
S.; Erker, G. Chem. Ber./Rec. 1997, 130, 201.
(13) For related diene cyclizations (using Pd and Rh) of limited scope,
see: (a) Bright, A.; Malone, J. F.; Nicholson, J. K.; Powell, J.; Shaw, B. L.
J. Chem. Soc., Chem. Commun. 1971, 712. (b) Grigg, R.; Malone, J. F.;
Mitchell, T. R. B.; Ramasubbu, A.; Scott, R. M. J. Chem. Soc., Perkin Trans.
1 1984, 1745.
(14) See Supporting Information for details of experimental procedures.
S0002-7863(97)03878-X CCC: $15.00 © 1998 American Chemical Society
Published on Web 07/28/1998

8008 J. Am. Chem. Soc., Vol. 120, No. 31, 1998
Table 1. Ni- and Pd-Catalyzed Cyclization of 1,6-Dienes
Communications to the Editor
Scheme 4. Chemo- and Regioselectivity of the Cyclization
Scheme 5. Mechanism of Intramolecular Hydrovinylation
out with Ni catalyst, since Pd catalyst gave diminished yields of
products.15 Even though the yields of the reactions are only
moderate, it is surprising that the sensitive allyl ether functionality
survives the reaction conditions. There are no known examples
of low-valent Zr-mediated (catalyzed or stoichiometric) cyclization
of substrates having an allyloxy group. The highly reducing
conditions involving low-valent Cp2Zr is incompatible with this
functional group.16 Note that the reaction is highly chemo- and
regioselective. However, cyclic product 9 is obtained as a mixture
of cis and trans (1:1) isomers. Substrate 10 gave an exceptionally
clean reaction leading to 11 in 95% isomeric purity. In each case,
formation of the indicated regioisomeric product can be rational-
ized by initial addition of the presumed LNi+-H intermediate (vide
infra) to the less hindered olefin. Even when there is the
possibility of an auxiliary coordination, (e.g., entry 8) the expected
regioisomer 12 is still the major product.
The mechanism of reaction remains speculative at present. One
likely scenario8,17 involves the formation of a metal hydride
(Scheme 5), followed by hydrometallation, cyclization, and
reductive elimination (see Scheme 1, path b). We have observed
that a number of (allyl)Ni(X)(phosphine) complexes used in this
study are excellent catalysts for isomerization of terminal olefins18
to internal olefins, a reaction characteristic of metal hydrides.19
a Isolated yield of pure (GC) product. b Ratios determined by GC.
c No cyclization was observed with Ni catalyst. d Substrate yielded
mixture of products, with only trace amounts of 5-membered furan
product formed when treated with Pd catalyst. e Substrate decomposed
1
when treated with Pd catalyst. f Ratios determined by H NMR.
more forcing conditions disubstituted olefins will participate in
the reaction (entry 3). It is particularly noteworthy that the Pd-
catalyzed reaction is more suitable for N-tosyl/N-acyl substituted
dienes (entries 4 and 5). Depending on the phosphine, both 5-
and 6-membered ring heterocycles are produced. Thus, in the
case of N-tosyldiallylamine, [(allyl)PdCl]2/Ph3P/AgOTf gave a
mixture of 5- and 6-membered heterocycles in a ratio of 82:18.
Use of (o-tolyl)3P as a ligand under the same conditions gave a
ratio of 38:62 of the same compounds (entries 4a and 4b). The
corresponding reaction with [(allyl)NiBr]2 gave a lower yield of
cyclic 5-membered product (entry 4c). The reaction appears to
be sensitive to the amine protecting group and phosphine used.
Thus, under the palladium/tri-o-tolylphosphine-mediated reaction
conditions, the N,N-diallylbenzamide gave exclusively the me-
thylene derivative (entry 5). Benzyldiallylamine (entry 6) and
other tertiary amines failed to undergo cyclization.
Acknowledgment. We are grateful to the National Science Foundation
(CHE-9706766), EPA/NSF Program for Technology for a Sustainable
Environment (EPA R826120-01-0) and the Petroleum Research Fund of
the ACS for financial support of this work.
Supporting Information Available: Details of experimental proce-
dures, spectroscopic and chromatographic data of products (48 pages,
print/PDF). See any current masthead page for ordering information and
Web access instructions.
JA9738788
(16) (a) Ito, H.; Motoki, Y.; Taguchi, T.; Hanzawa, Y. J. Am. Chem. Soc.
1993, 115, 8835. (b) Ito, H.; Taguchi, T.; Hanzawa, Y. J. Org. Chem. 1993,
58, 774.
(17) DiRenzo, G. M.; White, P. S.; Brookhart, M. J. Am. Chem. Soc. 1996,
118, 6225 and references therein.
(18) These include 1,7-dienes which undergo isomerization followed by
cyclization to give a mixture of products.
(19) (a) Parshall, G. W.; Ittel, S. D. Homogeneous Catalysis, 2nd ed.; John
Wiley: New York, 1992. (b) Evans, D.; Osborn, J.; Wilkinson, G. J. Chem.
Soc. A 1968, 3133. (c) Casey, C. P.; Cyr, C. R. J. Am. Chem. Soc. 1973, 95,
2248. (d) For HNi+L3-mediated olefin isomerization, see: Tolman, C. A.;
McKinney, R. J.; Seidel, W. C.; Druliner, J. D.; Stevens, W. R. AdV. Catal.
1985, 33, 1.
The remarkable functional group compatibility of this catalyst
system is best illustrated with substrates carrying allyl ether
functionality shown in Scheme 4. These reactions are carried
(15) For another approach to tetrahydrofurans from eneynes see: Trost,
B. M.; Edstrom, E. D.; Carter-Petillo, M. B. J. Org. Chem. 1989, 54, 4489.