Study on Nanocomposites between PdNPs and Layered Double Hydroxides for Challenging Organometallic Catalysis

A new catalytic approach for the C-O activation of enol phosphates based on a palladium supported on layered-double hydroxide is demonstrated. Hydrothermally treated LDH containing Pd(0) gave the best catalytic results. In particular, two different ketene aminal phosphates were used as models to study the synthesis of -phenyl enecarbamates N-Boc/ CBz under the Suzuki-Miyaura conditions. Importantly, the Boc substituted o-brominated enol phosphate was quite stable under the catalytic conditions when compared to the CBz counterpart. The use of an ortho-bromo aniline as precursor allowed the synthesis of the 2-phenyl indole through an arylation/ Heck cyclization in moderate yields. Catalyst reusability enabled the synthesis of the heterocycle in moderate yields for four consecutive runs.