Categories: C-C Bond Formation > Arenes, Cyclic Compounds >
Synthesis of indenes
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Recent Literature
The reaction of 2-(chloromethyl)phenylboronic acid with alkynes in the presence
of a Rh(I) catalyst gave indene derivatives in high yields. The regioselectivity
depends on the steric nature of the substituent on the alkynes.
M. Miyamoto, Y. Harada, M. Tobisu, N. Chatani, Org. Lett.,
2008,
10, 2975-2978.
In the presence of a catalytic amount of FeCl3, a broad range of N-benzylic
sulfonamides smoothly react with internal alkynes to afford various
functionalized indene derivatives with extremely high regioselectivity through
FeCl3-catalyzed cleavage of sp3 carbon-nitrogen bonds to
generate benzyl cation intermediates.
C.-R. Liu, F.-L. Yang, Y.-Z. Jin, X.-T. Ma, D.-J. Cheng, N. Li, S.-K. Tian, Org. Lett., 2010,
12, 3832-3835.
Cyclization of electron-rich 2-alkyl-1-ethynylbenzene derivatives was catalyzed
by TpRuPPh3(CH3CN)2PF6 in hot
toluene to form 1-substituted-1H-indene and 1-indanone products. The
cyclization mechanism involves a 1,5-hydrogen shift of an initial
metal-vinylidene intermediate.
A. Odedra, S. Datta, R.-S. Liu, J. Org. Chem., 2007,
72, 3289-3292.
Air-stable alkynophilic metal salts, such as PtCl2, PtCl4,
and [RuCl2(CO)3]2, catalyze the
cycloisomerization of 1-alkyl-2-ethynylbenzenes to produce substituted indenes.
Electrophilically activated alkynes can be intercepted by simple benzylic C-H
bonds at primary, secondary, and tertiary carbon centers.
M. Tobisu, H. Nakai, N. Chatani, J. Org. Chem., 2009,
74, 5471-5475.
A number of indenes have been prepared in good yields by treatment of o-bromobenzyl
zinc bromide with various terminal and internal alkynes in the presence of a
nickel catalyst. The nickel-catalyzed carboannulation reaction was successfully
extended to the synthesis of indanes using acrylates and styrene instead of an
alkyne.
R. Deng, L. Sun, Z. Li, Org. Lett., 2007,
9, 5207-5210.
The methylenindene scaffold can be prepared from readily available gem-dibromoolefins
using an efficient, highly modular palladium-catalyzed tandem intermolecular
Suzuki/intramolecular Heck reaction under mild conditions. The choice of ligand
was found to be crucial to control the selectivity of the reaction. Isolation of
intermediates under different conditions provides insight into the mechanism.
C. S. Bryan, M. Lautens, Org. Lett., 2010,
12, 2754-2757.
Arylboronate esters bearing a pendant Michael-type acceptor olefin undergo a
transmetalation with a rhodium-based catalytic complex. These organorhodium
intermediates can cyclize onto nonterminal acetylenes in good to excellent
yields.
M. Lautens, T. Marquardt, J. Org. Chem., 2004,
69, 4607-4614.
The preparation of indanones by the intramolecular acylation of 3-arylpropanoic
acids or halides requires the use of noncatalytic acid promoters. In the
presence of a catalytic amount FeCl3, in situ generated dimethyl
acetals of (E)-2-alkylcinnamaldehydes cyclize to 1-methoxy-2-alkyl-1H-indenes
in good-to-high yields. The 1-methoxyindenes were converted in high yield into
2-alkylindanones.
G. B. Womack, J. G. Angeles, V. E. Fanelli, C. A. Heyer, J. Org. Chem.,
2007,
72, 7046-7049.
