Pd-Catalyzed Highly Regio- and Stereoselective Formation of C–C Double Bonds: An Efficient Method for the Synthesis of Benzofuran-, Dihydrobenzofuran-, and Indoline-Containing Alkenes
A highly regio- and stereoselective C–C double bond formation reactionvia Pd-catalyzed Heck-type cascade process with N-tosylhydrazones has been developed. Various N-tosylhydrazones derived from both ketones and aldehydes are found to be efficient substrates to provide di- and trisubstitutedolefins with high regio- and stereoselectivity. Furthermore, this reaction has a good functional group tolerance
Saturated aldehydes and ketones are converted via their p-toluenesulfonyl hydrazones to the corresponding alkanes using dichloro bis(1,4-diazabicydo[2.2.2]octane)(tetrahydroborato) zirconium(IV) (ZrBDC). The reactions were performed in DMF-sulfolane at 110 °C and gave the corresponding alkanes in high yields. Regioselectivity in the reduction of α,β-unsaturated carbonyl groups was also observed.
An efficient one‐pot N‐alkylation of benzimidazole and benzotriazole from carbonyl compounds and tosylhydrazide has been accomplished via copper powder‐catalyzed N—H bond insertion affording N‐alkylated products in good yields. The reaction can tolerate a wide range of carbonyl compounds, such as aryl, alkyl, heterocyclic and α,β‐unsaturated ketones, and aldehydes.
coupling partners can be employed for the synthesis of conjugated dienes by palladium-catalyzed cross-coupling with tosylhydrazones: α,β-unsaturated ketone and aryl halide or alkenyl halide and non-conjugated tosylhydrazone. Depending on the substrate, a vinylogous hydride elimination is responsible for the formation of the final dienes.
Pd-Catalyzed Autotandem Reactions with <i>N</i>-Tosylhydrazones. Synthesis of Condensed Carbo- and Heterocycles by Formation of a C–C Single Bond and a C═C Double Bond on the Same Carbon Atom
作者:Miguel Paraja、Carlos Valdés
DOI:10.1021/acs.orglett.7b00613
日期:2017.4.21
A new Pd-catalyzed autotandem reaction is introduced that consists of the cross-coupling of a benzyl bromide with a N-tosylhydrazone followed by an intramolecular Heckreaction with an aryl bromide. During the process, a single and a double C–C bond are formed on the same carbon atom. Two different arrangements for the reactive functional groups are possible, rendering great flexibility to the transformation