Acid‐dependent selective formation of trans‐aryl(germyl)ethenes or 1‐aryl‐1‐germylethenes by the protodestannylation of (Z)‐germyl(stannyl)ethenes

Abstract

Protodemetallation of (Z)-1-aryl-2-germyl-1-stannylethenes using hydrochloric acid in the presence of tetraethylammonium chloride (TEACl) proceeds at 0 • C with retention of configuration to afford trans-1-aryl-2-germylethenes with high yields. In contrast, the reaction using hydroiodic acid in the presence of tetrabutylammonium iodide (TBAI) brings about a novel 1,2-germyl migration accompanying the destannylation to form 1-aryl-1-germylethenes. These 1,2-germyl migration products result with especially high selectivity from adducts bearing a substituent at the ortho-or para-position on the aromatic ring in the adduct. However, the germyl(stannyl)ethenes bearing a substituent at the meta position on the ring produce a regioisomeric mixture of a trans-germylethene and a 1-aryl-1-germylethene.

Syntheses and Ligand Exchange Reaction of Iron(IV) Complexes with Two Different Group 14 Element Ligands, Cp(CO)FeH(EEt3)(E′Et3) (E, E′ = Si, Ge, Sn)

“…Transition-metal complexes with two group 14 element ligands, especially for nickel triads, have attracted considerable attention, because these complexes are considered to be key intermediates in the catalytic addition of E−E′ bonds (E, E′ = Si, Ge, Sn) to unsaturated organic molecules. , With iron complexes, several compounds with two group 14 element ligands have been reported, but most of them have the same group 14 element ligands. Very recently, we found that an iron(IV) complex with two silyl ligands, Cp(CO)FeH(SiR 3 ) 2 (Cp stands for η 5 -C 5 H 5 ), exhibits reductive elimination of the two silyl groups in DMF and created a new catalytic system for dehydrogenative Si−Si bond coupling of tertiary silanes promoted by Cp(CO) 2 FeMe .…”

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

“…Filtration of the liberated crystalline Bu 3 SnF and ether extraction of the organic phase, followed by drying over Na 2 SO 4 , evaporation with a rotary evaporator and column chromatography [silica gel (Kanto Kagaku Co. Ltd, Japan, 60N, spherical, 40-50 µm, neutral, for flash chromatography; if the same silica gel we used to purify the cross-coupling products is not available, Harrowven's method is recommended for the purification of products), [15] (meta-carbon of phenyl group trans to germanium), 128.9 (metacarbon of phenyl group cis to germanium), 128 (para-carbon of phenyl group trans to germanium), 127.8 (para-carbon of phenyl group cis to germanium), 127.34 (ortho-carbon of phenyl group cis to germanium), 127.3 (ortho-carbon of phenyl group trans to germanium), 127.2 (vinyl carbon bearing germyl group), 9.0 (C1 of ethyl group) and 5.6 (C2 of ethyl group) ppm. The assignment of the aromatic carbons is based on intensity information, the additivity of the chemical shifts [16] and reported 13 C-NMR data of styrylgermanes [17] and -silanes. [ By a procedure similar to that for 2a, other arylation products were obtained from the corresponding (Z)-1.…”

Synthesis of novel stereodefined vinylgermanes bearing an allyl group or an allenyl group: (E)‐2‐aryl‐1‐germylalka‐1,4‐dienes and (E)‐4‐aryl‐5‐germylpenta‐1,2,4‐trienes

“…to the exclusive formation of undesired (E)-styryltriethylgermane. 23 Since the cross-coupling did not occur in a similar reaction in the absence of copper iodide, it is suggested that (E)-styryltriethylgermane may be formed by the decomposition of a putative vinyl copper species such as 1a-Cu in Scheme 8 produced from the transmetallation of 1a with copper iodide.…”