Dicobalt octacarbonyl catalyzed carbonylated cycloaddition of triynes to functionalized tetracycles

Article abstract of DOI:10.1021/ol015635x

(matrix presented) We have demonstrated that a dicobalt octacarbonyl catalyzed double [2 + 2 + 1] carbonylative cycloaddition reaction of triyne can be carried out to yield a novel 5.5.5.6 tetracyclic di-enone system.

Full text of DOI:10.1021/ol015635x

ORGANIC
LETTERS
2001
Vol. 3, No. 7
1065-1067
Dicobalt Octacarbonyl Catalyzed
Carbonylated Cycloaddition of Triynes
to Functionalized Tetracycles
Seung Uk Son, Young Ae Yoon, Dai Seung Choi, Jin Kyoon Park,
B. Moon Kim, and Young Keun Chung*
School of Chemistry and Center for Molecular Catalysis, Seoul National UniVersity,
Seoul 151-747, Korea
ykchung@plaza.snu.ac.kr
Received January 31, 2001
ABSTRACT
We have demonstrated that a dicobalt octacarbonyl catalyzed double [2 + 2 + 1] carbonylative cycloaddition reaction of triyne can be carried
out to yield a novel 5.5.5.6 tetracyclic di-enone system.
Recently, we have demonstrated1 that the generation and
stabilization of cyclopentadienones through the use of cobalt
carbonyl could be an attractive method for the construction
of five-membered ring systems. Reaction sequences starting
from dienyne or ene-diyne2 have successfully provided
[4.5.5.5] fenestrane (A) and [5.5.5.5]fenestrane (B), respec-
tively (Figure 1). These studies suggested that triynes (C)
might be appropriate precursors for the construction of
tetracycles possessing a fenestrane structure3 through two
sequential [2 + 2 + 1] cycloaddition reactions. However,
when a triyne was treated with dicobalt octacarbonyl in the
presence of CO, a 5.5.5.6 tetracyclic structure was obtained
as a sole product.
For the cyclization, a variety of triyne derivatives (com-
pound 1, Scheme 1) were prepared, where X,Y ) O, NR,
and CH2. Treatment of triyne 1a with Co2(CO)8 (2.5 mol
%) in CH2Cl2 at 130 °C for 1 day afforded the tetracyclic
compound 2a in 75% yield.4
Herein we report a new cobalt carbonyl catalyzed double
[2 + 2 + 1]carbonylative cycloaddition reaction of triynes
yielding novel 5.5.5.6 tetracyclic compounds, which can be
utilized as versatile intermediates for polyquinane synthesis.
(1) (a) Hong, S. H.; Choi, D. S.; Chung, Y. K.; Lee, S. Chem. Commun.
1999, 2099. (b) Son, S. U.; Paik, S.-J.; Lee, S. I.; Chung, Y. K. J. Chem.
Soc., Perkin Trans. 1 2000, 141. (c) Son, S. U.; Choi, D. S.; Chung, Y. K.
Org. Lett. 2000, 2, 2097. (d) Son, S. U.; Chung, Y. K.; Lee, S. G. J. Org.
Chem. 2000, 65, 6142.
(2) (a) Smit, W. A.; Buhanjuk, S. M.; Simonyan, S. O.; Shahkov, A. S.;
Struchkov, Y. T.; Yanovsky, A. I.; Caple, R.; Gybin, A. S.; Anderson,
L. G.; Whiteford, J. A. Tetrahedron Lett. 1991, 32, 2105. (b) Thommen,
M.; Veretenov, A.; Guidetti-Grept, R.; Keese, R. HelV. Chim. Acta. 1996,
79, 461. (c) van der Waals, A.; Keese, R. J. Chem. Soc., Chem. Commun.
1992, 570. (d) Thommen, M.; Gerber, P.; Keese, R. Chimia 1991,
21-24.
Figure 1. Some tandem cyclizations for synthesis of polyquinanes.
10.1021/ol015635x CCC: $20.00 © 2001 American Chemical Society
Published on Web 03/15/2001

Table 1. Double [2 + 2 + 1] Reaction in Triynesa
Scheme 1
The product 2a could provide a ready access to a variety
of substituted polyquinane structures, which belong to a
rapidly growing subgroup of terpene natural products and
are associated with a wide range of biological activities.5 It
is of a particular note that, in one operation, six carbon-
carbon bonds have been formed simultaneously, housing four
rings in a single molecule. As expected, the double bond of
the cyclopentadienone from the first cyclization has been
used as an alkene part of the second Pauson-Khand reaction.
However, as a result of the steric effect of the TIPS group,
the second reaction occurred in the intermediate between the
unsubstituted double bond and the triple bond. The structural
proof of the tetracyclic structure was obtained through an
X-ray study of 2b (Figure 2).6
a Reaction conditions: 130 °C, 18 h 30 atm CO, 2.5 mol % Co2(CO)8,
CH2Cl2. b Isolated yield.
change in the steric environment appears to impose a
substantial effect on the reaction course. Despite the poor
yield, the formation of 2e is still catalytic with a turnover
number of 4. Treatment of 1f under the same reaction
conditions provided no detectable products. Instead, forma-
tion of an untractable polymeric material was observed.
(3) Reviews on fenestrane chemistry: (a) Kuck, D. In AdVances in
Theoretically Interesting Molecules; Thummel, R. P., Ed.; JAI Press:
Greenwich, CT, 1998; Vol. 4, p 81 f. (b) Thommen, M.; Keese, R. Synlett
1997, 231. (c) Luef, W.; Keese, R. In AdVances in Strain in Organic
Chemistry; Halton, B., Ed.; JAI Press: Greenwich, CT, 1993; Vol. 3, p
229 f. (d) Agosta, W. C. In The Chemistry of Alkanes and Cycloalkanes;
Patai. S., Rappoport, Z., Eds.; Wiley: New York, 1992; p 927 f. (e) Gupta,
A. K.; Fu, X.; Snyder, J. P.; Cook, J. M. Tetrahedron 1991, 47, 3665. (f)
Krohn, K. In Organic Synthesis Highlights; Mulzer, J., Altenbach, H.-J.,
Braun, M., Krohn, K., Reissig, H.-U., Eds.; VCH: Weinheim, 1991; p 121
f. (g) Venepalli, B. R.; Agosata, W. C. Chem. ReV. 1987, 87, 399. (h) Keese,
R. In Organic Synthesis: Modern Trends; Chizhov, O., Ed.; Blackwell:
Oxford, 1987; p 43 f. (i) Keese, R. Nach. Chem. Technol. Lab. 1982, 30,
844.
Figure 2. X-ray stucture of 2b.
(4) Characterization of 2a. 1H NMR (300 MHz, CDCl3): δ 5.98 (s, 1
H), 5.54 (br s, 1 H), 4.79 (d, 14.0 Hz, 1 H), 4.69 (d, 14.0 Hz, 1 H), 4.45
(d, 8.1 Hz, 1 H), 4.09 (d, 8.1 Hz, 1 H), 3.35 (s, 1 H), 1.36 (m, 3 H), 1.01
(m, 18 H) ppm. 13C NMR (75 MHz, CDCl3): δ 201.9, 196.1, 184.7, 174.4,
124.5, 120.1, 94.2, 69.1, 62.9, 60.1, 58.8, 18.4, 18.3, 10.9 ppm. IR (NaCl)
ν CdO 1724, 1691 cm-1. Anal. Calcd for C20H28O4Si: C, 66.63; H, 7.83.
Found: C, 66.50; H, 8.10.
(5) For a review on polyquinanes, see: (1) Mehta, G.; Srikrishna, A.
Chem. ReV. 1997, 97, 671-719. (2) Paquette, L. A.; Doherty, A. M. Recent
Synthetic DeVelopments in Polyquinane Chemistry; Springer-Verlag: New
York, 1987. (3) Paquette, L. A. Top. Curr. Chem. 1984, 119, 1. (4) Ramaiah,
M. Synthesis 1984, 529. (5) Trost, B. M. Chem. Soc. ReV. 1982, 11, 141.
(6) Paquette, L. A. Top. Curr. Chem. 1979, 79, 41.
Encouraged by the formation of 2a and 2b, we have tested
a variety of triynes (Table 1). Cycloaddition reaction of 1c-e
under the same reaction conditions gave tetracyclic dienone
2c,d in reasonable to high yields. However, treatment of 1e
under the same reaction conditions gave 2e in 10% yield. It
was expected that the yield of 2e would be close to that of
2b since 1e appears to be quite akin to 1b except for the
dimethyl substituents on the carbon bridge. However, the
steric effect of the dimethyl group on the cycloaddition
reaction would be considerably larger than expected. A subtle
(6) Information for crystal. Crystal system, triclinic, space group, P-1,
unit cell dimensions a ) 7.8074(3), b ) 14.7100(6), c ) 18.4775(8) Å; R
) 104.428(2)°, â ) 94.084(3)°, γ ) 92.151(3)°. Final R indices [I > 2σ(I)],
R1 ) 0.0716, wR2 ) 0.1759.
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Org. Lett., Vol. 3, No. 7, 2001

It is interesting to note that, in all cases examined, the
first cyclization occurred to form a bicyclic dienone contain-
ing a heteroatom in the ring system.
Scheme 2
For compound 1g, no reaction was observed under the
same reaction conditions as a result of the steric effect of
the substituents. Thus, it seems that the steric bulkiness helps
the cycloaddition reaction to afford tetracyclic compounds;
however, excess steric effect hinders the progress of the
cycloaddition reaction.
high conversion rate of the cycloaddition reaction are
noteworthy. The reaction described will doubtlessly be
further developed since the assembly of four rings in one
operational step makes it a worthwhile competitor to other
methods.
We have screened other triynes having an alkyl and benzyl
group at center alkyne that are sterically less cumbersome
than 1a-e. Instead of cycloaddition products, untractable
polymeric materials were obtained.
Thus, the steric effect of the substituent in the inner triple
bond plays an important role in controlling the destiny of
the reaction path. Thus, the dicobalt octacarbonyl catalyzed
double [2 + 2 + 1] carbonylative cycloaddition of triyne is
quite unique for triynes having a TIPS group in the inner
triple bond.
Acknowledgment. This work was supported by grant
2000-2-12200-001-1 from the Basic Research Program of
the Korea Science and Engineering Foundation (KOSEF) and
the KOSEF through the Center for Molecular Catalysis.
S.U.S., Y.A.Y., and J.K.P. thank the Brain Korea 21
fellowship.
A plausible reaction mechanism is provided in Scheme 2.
In conclusion, we have demonstrated that by designing
triynes bearing a proper steric group, a dicobalt octacarbonyl
catalyzed double [2 + 2 + 1] carbonylative cycloaddition
reaction of triyne can be carried out to yield a novel 5.5.5.6
tetracyclic di-enone system. The experimental simplicity and
Supporting Information Available: General experimen-
tal procedures and characterization data of compounds. This
material is available free of charge via the Internet at
http://pubs.acs.org.
OL015635X
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