α-Vinylated ketoester are atom-economically produced by an In(OTf)3-catalyzed addition of β-ketoesters to welding-grade acetylene in the presence of molecular sieves under solvent-free conditions in good to excellent yield.
M. Nakamura, K. Endo, E. Nakamura, Org. Lett., 2005, 7, 3279-3281.
A regio- and stereoselective addition of 1,3-diketones to unfunctionalized internal alkynes under neutral conditions is achieved by using [Ir(cod)2]SbF6 as a catalyst.
G. Onodera, M. Kato, R. Kawano, Y. Kometani, R. Takeuchi, Org. Lett., 2009, 11, 5038-5041.
Indium-catalyzed addition of 1,3-dicarbonyl compounds to 1-iodo-1-alkynes produces exclusively E-iodoalkenes. The iodine atom serves both as an activating group and as a group that controls the regioselectivity of the addition. The E-alkenyl iodide product can be further derivatized into trisubstituted olefins in high overall yield with retention of the stereochemistry.
H. Tsuji, T. Fujimoto, K. Endo, M. Nakamura, E. Nakamura, Org. Lett., 2008, 10, 1219-1221.
1,3-Dicarbonyl compounds add to unactivated alkynes in the presence of less than 1 mol-% of indium(III) trifluoromethanesulfonate in high to excellent yield to give 2-alkenylated 1,3-dicarbonyl compounds. This mild reaction does not require solvent and tolerates various functional groups.
K. Endo, T. Hatakeyama, M. Nakamura, E. Nakamura, J. Am. Chem. Soc., 2007, 129, 5264-5271.
The Bu3P-catalyzed addition of 1,3-diketones, β-keto esters and malonates to alkynoates allows an improved, mild and efficient one pot access to α-(gem-difunctional) cinnamate esters and to conjugated 1,3-diketones.
M. HanÚdanian, O. Loreau, M. Sawicki, F. Taran, Tetrahedron, 2005, 61, 2287-2294.
An organocatalytic asymmetric cascade Michael reaction of α,β-unsaturated aldehydes with bromomalonates, efficiently catalyzed by chiral diphenylprolinol TMS ether in the presence of base 2,6-lutidine, gives cyclopropanes in high enantio- and diastereoselectivities. Using NaOAc as base, a spontaneous ring-opening of cyclopropanes leads to (E) α-substituted malonate α,β-unsaturated aldehydes.
H. Xie, L. Zu, H. Li, J. Wang, W. Wang, J. Am. Chem. Soc., 2007, 129, 10886-10894.
A tandem condensation of propiolamide and cyclic β-keto methyl esters in water, followed by acid- or base-promoted intramolecular ring closure and decarboxylation enables an efficient synthesis of a 5,6-fused 2-pyridone ring system.
A. B. Smith, III, O. Atasoylu, D. C. Beshore, Synlett, 2009, 2643-2646.
An enantioselective Conia-ene reaction of acetylenic β-dicarbonyl compounds employs a DTBMSegphos-Pd(II)/Yb(III) dual catalyst system that allows for the asymmetric synthesis of all-carbon quaternary centers and generates a methylene cyclopentane containing an alkene that can be further manipulated.
B. K. Corkey, F. D. Toste, J. Am. Chem. Soc., 2005, 127, 17168-17169.
[ReBr(CO)3(thf)]2 catalyzed the reactions of 1,3-dicarbonyl compounds with terminal acetylenes, which gave the corresponding alkenyl derivatives in excellent yields.
Y. Kuninobu, A. Kawata, K. Takai, Org. Lett., 2005, 7, 4823-4825.
A Ni(II)-catalyzed Conia-ene reaction of various acetylenic 1,3-dicarbonyl compounds has been discovered. The reaction gave mono- and bicyclic olefinic cyclopentantes in good yields in the presence of Ni(acac)2 and Yb(OTf)3.
Q. Gao, B.-F. Zheng, J.-H. Li, D. Yang, Org. Lett., 2005, 7, 2185-2188.
An organocatalytic highly enantioselective formation of vinyl-substituted all-carbon quaternary stereocenters proceeds in good yield via nucleophilic vinylic substitution of various α-substituted-α-cyanoacetates with α-chloroalkenones using a dimeric cinchona alkaloid phase-transfer catalyst.
M. Bell, T. B. Poulsen, K. A. J°rgensen, J. Org. Chem., 2007, 72, 3053-3056.