Categories: C-C Bond Formation > Arenes, Cyclic Compounds >
Synthesis of indenes
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Recent Literature
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.
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.
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 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.
