Synthesis of N‐Heterocycles‐Fused Azasilines by Palladium‐Catalyzed Si‐Si Bond Activation

Abstract

Azasilines fused nitrogen heterocycles are prepared in excellent yields (from 74 to 98 % according to the structures) for the first time in one operation with high regio‐ and stereoselectivities. The key step consists of an intramolecular palladium‐catalyzed cyclisation reaction of heteroaryl disilane cores, bearing double or triple bond. We first studied the reactivity of pyridyl heterocycles, using xylenes as solvent and Pd(dba)2‐P(OEt)3 as catalyst at 130 °C. The Z configuration of the adducts suggested that the reaction proceeds following a syn addition on the alkyne. This strategy has then been illustrated by the synthesis of complex polyheterocyclic scaffolds (phenothiazine, indole, carbazole, quinoline and tetrahydroquinoline) starting from other nitrogen heteroaryl compounds, to demonstrate the potential of the process, in order to obtain promising biological scaffolds.

Advances in disilylation reactions to access cis/trans-1,2-disilylated and gem-disilylated alkenes

“…Soonafter, the same research group developed a similar valuable reaction for the synthesis of N-heterocycle-fused silanes using heteroaryl alkynylsilanes as substrates under their previously established Pd/P(OEt) 3 catalytic system, 132 achieving the desired products in moderate to excellent yields (Scheme 11). 133 The reaction demonstrated high regio- and stereo-selectivity, proceeding through palladium-catalyzed intramolecular cyclization reactions of the Si–Si bond on the heteroaryl disilanes with the triple bond. The evaluation of the substrate scope of this reaction showcased good tolerance to various substituents on the alkynes under standard conditions.…”

Synthesis of 6-membered germacycles by intramolecular germylzincation of alkynes

“…We first developed access to silylated and germylated heterocycles based on an anionic rearrangement. 6 Then, we developed new strategies to access silylated heterocycles through Pd-catalyzed cyclization reactions through C–H activation of a methyl group of TMS, 7 or Si–Si bond activation 8 of disilanes. More recently, we disclosed an easy access to germoles by treatment of ortho -alkynyl aryldiphenylgermanes in the presence of diethylzinc and AIBN as radical initiator (Scheme 1, top).…”

Meet the Women of Catalysis

“…Her research focused on intramolecular cyclization reactions by carbometallation with lithium, magnesium, nickel and palladium catalysts, which allow access to various complex polycyclic scaffolds. Recently, she focused her attention on the synthesis of silylated heterocycles, and opened new strategies to generate valuable scaffolds …”