Categories: C=C Bond Formation >
Synthesis of cycloalkenes
An oxidation-methylenation one-pot procedure in the presence different catalysts produced terminal alkenes in high yields. A methylenation-ring-closing process for the synthesis of cyclic alkenes from carbonyl derivatives was even expanded with an initial oxidation to allow the use of alcohols as substrates.
H. Lebel, V. Paquet, J. Am. Chem. Soc., 2004, 126, 11152-11153.
A sequence of Pd-catalyzed haloallylation of alkynes, Pd-catalyzed cross-coupling, and Ru-catalyzed ring-closing metathesis enables a short approach to various 1,2-disubstituted cyclopentadienes. The scope of the method is broad.
N. Topolovčan, I. Panov, Martin Kotora, Org. Lett., 2016, 18, 3634-3637.
The GaCl3-catalyzed skeletal reorganization of enynes is simple and provides a diverse range of dienes in good to high yields. The reaction of enynes proceeds in a stereospecific manner with respect to the geometry of the olefin moiety.
N. Chatani, H. Inoue, T. Kotsuma, S. Murai, J. Am. Chem. Soc., 2002, 124, 10294-10295.
A mild, palladium-catalyzed intramolecular oxidative alkylation of various ζ-alkenyl β-diketones and ζ-alkenyl β-keto esters in the presence of CuCl2 at room temperature formed the corresponding 2-cyclohexenones in high yield.
T. Pei, X. Wang, R. A. Widenhoefer, J. Am. Chem. Soc., 2003, 125, 648-649.
An efficient and regioselective Yb(OTf)3-promoted palladium-catalyzed oxidative cyclization of γ-heteroalkenyl β-keto amides has been developed. Under simple aerobic condition, various six-, seven-, and eight-membered-ring N- and O-heterocycles were obtained in excellent yield.
K.-T. Yip, J.-H. Li, O.-Y. Lee, D. Yang, Org. Lett., 2005, 7, 5717-5719.
Cycloalkenes can be efficiently prepared by a new Ru-catalyzed decarbonylative cyclization of terminal alkynals. Under appropriate conditions, cycloisomerizations to conjugated aldehydes may be observed. Both processes involve catalytic Ru vinylidenes.
J. A. Varela, C. Gonzlez-Rodríguez, S. G. Rubín, L. Castedo, Carlos Saá, J. Am. Chem. Soc., 2006, 128, 9576-9577.
A sequence of two gold(I)-catalyzed isomerization steps allows the synthesis of functionalized acetoxy bicyclo[3.1.0]hexenes from 5-en-2-yn-1-yl acetates. Acetoxy bicyclo[3.1.0]hexene products can be further transformed to 2-cycloalkenones by simple methanolysis.
A. Buzas, F. Gagosz, J. Am. Chem. Soc., 2006, 128, 12614-12615.