Palladium-Catalyzed Disilylation and Digermanylation of Alkene Tethered Aryl Halides: Direct Access to Versatile Silylated and Germanylated Heterocycles

Abstract

A method for the palladium-catalyzed disilylation and digermanylation of aryl halides bearing a tethered alkene has been developed. The mechanism is thought to proceed via Heck-type cyclization, followed by C−H activation, resulting in a reactive fusedpalladacycle. A wide variety of disilylated and digermanylated heterocycles are obtained from readily available aryl halides in high yields with various functional groups. Moreover, the developed protocol proved to be highly diastereoselective.

Germylation of Arenes via Pd(I) Dimer Enabled Sulfonium Salt Functionalization

“…While the former method suffers from the reactive nature of such organometallic reagents that may limit functional group tolerance, the latter required relatively high temperature or a significant excess of germane or showed limited scope. There are only few examples of direct C–H germylation under transition-metal catalysis; these methods are characterized by the need for a directing group (to yield predominantly ortho -functionalization), harsh conditions (>100 °C), and limited functional group tolerance.…”

Asymmetric Disilylation of Spirocyclic Palladacyclopentanes via Tandem Heck/C−H Activation of Aryl Iodides

“…Organosilicon compounds are well applied in synthetic organic chemistry [1] materials, [2] pharmaceuticals, [3] agrochemicals, [4] and the new applications of organosilicon compounds continue to discover in each research area [5] . Transition metal‐catalyzed C−H silylation is one of the most important synthetic method for the preparation of silyl‐functionalized organic molecules, [6] In recent years, Zhang, [7] Liang, [8] Cheng, [9] and Lautens's [10] research groups have committed to developing an efficient disilylation reaction of hexamathylsilane with aryl halides in the presence of palladium catalyst to synthesis the corresponding disilylated products. In these strategies palladium‐catalyzed tandem Heck/remote C−H activation of aryl halides bearing a styrene moiety via a linkage to generate a spirocyclic palladapentanecycle is a key intermediate to construct the disilylated products.…”

Exploiting the Versatility of Palladium Catalysis: A Modern Toolbox for Cascade Reactions

“…Lautens group demonstrated the disilylation and digermanylation methodology to furnish chroman (17-82 % yield; 95 : 5 dr), isochroman (30-90 % yield; > 95 : 5 dr), and N-heterocyclic motifs 360 (30-94 % yield; 88 : 12 -93 : 7 dr) via a sequential intramolecular Heck insertion and CÀ H activation of aryl halides possessing various linkers with an alkene (Scheme 56). [79] The same group recently reported an insertion/CÀ H functionalization cascade to access a wide range of complex spirocycles 362. [80] The reaction proceeds via a spiropalladacycle that could be coupled with benzynes, alkynes, etc., to afford spiro-oxindoles or spiro-dihydridobenzofuran 365.…”