Alternative Synthesis of (Z)-1-Aryl-1-(tributylstannyl)-2-(triethylgermyl)ethenes and the Unprecedented Germyl 1,2-Migration during the Destannylation of the Adducts

Abstract

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The first stereospecific arylation of (Z)‐germyl(stannyl)ethenes with an aryl halide or heteroaryl halide under palladium‐catalysis

“…In closing, Pd(dba) 2 -PPh 3 -CuI-LiCl and Pd(dba) 2 -P(2-furyl) 3 -CuI-LiCl were found for the first time to be quite active catalysts in the coupling of an aromatic ring with a vinylgermane unit by the use of (Z)-germyl(stannyl)ethenes. The palladium-catalyzed cross-coupling of (Z)-germyl(stannyl)ethenes with aryl halides proceeds with retention of configuration, producing (germyl)vinylarenes in good to high yields.…”

“…[1,2] (Z)-1-Aryl-1-(tri-n-butylstannyl)-2-(triethylgermyl)ethenes, (Z)-1, [3,4] seem to provide good building blocks to synthesize new types of phenyleneethynylenes with terminal (germyl)ethenyl unit(s) through a combination of a Migita-Kosugi-Stille type reaction † [5 -8] and a Sonogashira-Hagihara reaction ( † Organotins, organoborons and organosilicons are known to work as cross-coupling reagents in the presence of a transition metal complex catalyst; among them, organotins [e.g. tri-n-butyl(organo)tins] are stable in air, but reactive in palladium-catalyzed cross-coupling, while organoborons require a base for the reaction to occur, and organosilicons need a special group(s) [e.g.…”

“…The reaction of (Z)-1-(tri-n-butylstannyl)-2-(triethylgermyl)-1-phenylethene (Z)-1a [3,4] with iodobenzene was selected as a model to compare reaction conditions. Thus, a combination catalyst of Pd(dba) 2 -PPh 3 -CuI (dba: dibenzylideneacetone) in dry DMF (N,N-dimethylformamide) at 70…”

“…The reaction produced triethyl(2,2-diphenylethenyl)germane 2a in 40% yield. A Pd(dba) 2 -P(2-furyl) 3 -CuI combination catalyst was also active in the reaction, affording 2a in 56% yield. Interestingly, Pd(dba) 2 -PPh 3 -CuI-LiCl and Pd(dba) 2 -P(2-furyl) 3 -CuI-LiCl catalyzed the reaction more efficiently, providing 2a in 89% and 80% yields, respectively.…”

“…A Pd(dba) 2 -P(2-furyl) 3 -CuI combination catalyst was also active in the reaction, affording 2a in 56% yield. Interestingly, Pd(dba) 2 -PPh 3 -CuI-LiCl and Pd(dba) 2 -P(2-furyl) 3 -CuI-LiCl catalyzed the reaction more efficiently, providing 2a in 89% and 80% yields, respectively. BnPdCl(PPh 3 ) 2 -CuI-LiCl and Pd(dba) 2 -P(2-tol) 3 -CuI-LiCl (2-tol: 2-methylphenyl) were, on the contrary, less effective, giving 2a in 38 and 24% yields, respectively.…”