- Ligand-Controlled Palladium-Catalyzed Carbonylation of Alkynols: Highly Selective Synthesis of α-Methylene-β-Lactones
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The first general and regioselective Pd-catalyzed cyclocarbonylation to give α-methylene-β-lactones is reported. Key to the success for this process is the use of a specific sterically demanding phosphine ligand based on N-arylated imidazole (L11) in the presence of Pd(MeCN)2Cl2 as pre-catalyst. A variety of easily available alkynols provide under additive-free conditions the corresponding α-methylene-β-lactones in moderate to good yields with excellent regio- and diastereoselectivity. The applicability of this novel methodology is showcased by the direct carbonylation of biologically active molecules including natural products.
- Beller, Matthias,Ge, Yao,Jackstell, Ralf,Jiao, Haijun,Liu, Jiawang,Spannenberg, Anke,Yang, Ji,Ye, Fei
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supporting information
p. 21585 - 21590
(2020/09/23)
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- Synthesis of acetylenic alcohols with calcium carbide as the acetylene source
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Propargyl alcohols containing a terminal alkyne group are highly important and versatile intermediates. Here, we report the synthesis of these compounds from an inexpensive and renewable resource, calcium carbide (CaC2). No metal catalysts are required in this new protocol and the reactions take place under very mild conditions.
- Sum, Yin Ngai,Yu, Dingyi,Zhang, Yugen
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supporting information
p. 2718 - 2721
(2013/10/08)
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- Carbon-carbon bond formation in regio- and stereoselective palladium-catalyzed cyclization of allene-substituted conjugated dienes
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Regio- and stereoselective palladium-catalyzed reactions of allene-substituted 1,3-dienes 1 in acetic acid at room temperature lead to cyclization with formation of a carbon-carbon bond between the middle carbon of the allene and the terminal carbon of the 1,3-diene. Two different types of reactions, both that constitute 1,4-carboacetoxylations of the 1,3-diene, have been developed. In one of the reactions, Pd(II) catalyzes the oxidation of 1 to bicyclic compounds 2, and in the other, Pd(0) catalyzes the transformation of 1 to bicyclic compounds 3. The products 2 are useful for further synthetic tr0nsformations and undergo Diels-Alder reactions with dienophiles to give polycyclic ring systems.
- Loefstedt, Joakim,Franzen, Johan,Baeckvall, Jan-E.
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p. 8015 - 8025
(2007/10/03)
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