Two quaternary carbon centers are created in the title reaction to form fused dihydropyrans (see scheme). The same catalyst promotes the ortho functionalization of aryl ketones with 1,6‐enynes with excellent regio‐ and enantioselectivity. Z=amide, C(CO2Me)2, O; E=CO2Et, Ac; R1=Me, aryl, CO2Me; R2=Me; R3=Me, CO2Et.
We have determined that a cationic rhodium(I)/H8-BINAP complex catalyzes a [2 + 2 + 2] cycloaddition of both activated and unactivated carbonyl compounds with 1,6-diynes leading to dienones in high yields. On the other hand, unactivated aryl ketones react with 1,6-diynes in the presence of a cationic rhodium(I)/Segphos complex to give ortho-functionalized aryl ketones in high yields.
A cationic rhodium(I)/BIPHEP complex catalyzes amide-directed regioselective alkenylations of olefinic or aromatic sp(2) C-H bonds in good yields under mild reaction conditions. The use of a 1-pyrrolidinecarbonyl group as a directing group dramatically accelerates the reaction.
We have established that a cationic rhodium(I)/H 8 -binap complex catalyzes [2+2+2] cycloadditions of a variety of 1,6-and 1,7-diynes with both electron-deficient and electron-rich carbonyl compounds, leading to dienones in high yield under mild reaction conditions. In the reactions with acyl phosphonates, the reactivity of 1,6-and 1,7-diynes was highly dependent on their own structures. The addition of chelating diethyl oxalate effectively promoted the [2+2+2] cycloadditions involving acyl phosphonates, presumably due to the
We have developed the first catalytic cycloisomerization of 1,6- and 1,7-diynes leading to trienes and vinylpyrroles by using a cationic rhodium(I)/Segphos complex (2.5-10 mol %) and 1,2-cyclohexanedione (100 mol %). 1,2-Cyclohexanedione may effectively occupy vacant coordination sites and thus promote the present cycloisomerization.
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