Michael-type hydroarylation

Ohe, T. Uemura, S. A novel catalytic activity of Bi(III) salts in Pd(II)-catalyzed atom economical Michael-type hydroarylation of nitroalkenes with aryltin compounds. Tetrahedron Lett. 2002, 43, 1269-1271. 

Scheme 7.62 Example of intermolecular Michael-type hydroarylation of in situ generated o-quinone methides with tertiary aromatic amines.

In the reaction of Q,/3-unsaturated ketones and esters, sometimes simple Michael-type addition (insertion and hydrogenolysis, or hydroarylation, and hydroalkenylation) of alkenes is observed[53,54]. For example, a simple addition product 56 to methyl vinyl ketone was obtained by the reaction of the heteroaromatic iodide 55[S5]. The corresponding bromide affords the usual insertion-elimination product. Saturated ketones are obtained cleanly by hydroarylation of o,/3l-unsaturated ketones with aryl halides in the presence of sodium formate, which hydrogenolyses the R—Pd—I intermediate to R— Pd—H[56]. Intramolecular hydroarylation is a useful reaction. The diiodide 57 reacts smoothly with sodium formate to give a model compound for the afla-toxin 58. (see Section 1.1.6)[57]. Use of triethylammonium formate and BU4NCI gives better results. 

Under palladium catalysis, a,/3-unsaturated ketones can undergo Michael-type Heck hydroarylationsJ Recently, the intermolecular hydroarylation of 19 has been realized in supercritical carbon dioxide as a solvent to furnish the products 21 (Scheme Triethylamine is believed to be the source of hydride in these transformations. With certain combinations of substituents R R on the enone 19 and the aryl iodide, significant fractions of the /3-dehydropalladation products 22 were also formed, and the aryl-substituted unsaturated 22 was the sole product when acrylates 19 (R = OEt) were subjected to these conditions. The highly di-diastereoselective hydroarylation of an a,/3-unsaturated ketone 23 (Scheme has been applied in an intramolecular fashion toward the synthesis of the octahydrophenanthrene derivative 24, a novel biomarker from Brazilian marine evaporitic Carmopolis oil. 

---