A highly efficient synthesis of (Z)‐1‐aryl‐2‐silyl‐1‐ stannylethenes and their conversion to (E)‐2‐ arylethenyl‐, (Z)‐2‐(2‐pyridyl)ethenyl‐ and allenyl‐silanes

Stereospecific synthesis of a family of novel (E)‐2‐aryl‐1‐silylalka‐1,4‐dienes or (E)‐4‐aryl‐5‐silylpenta‐1,2,4‐trienes via a cross‐coupling of (Z)‐silyl(stannyl)ethenes with allyl halides or propargyl bromide

“…[32,33] Allyl halides, propargyl bromide and benzyl(chloro)bis(triphenylphosphine)palladium(II) were purchased from Tokyo Kasei Co. and used as received. Copper(I) iodide, triphenylphosphine, tri(o-tolyl)phosphine (o-tolyl: o-methylphenyl), triethylphosphite, palladium chloride and palladium acetate were purchased from Wako Chemical Co. and used as received.…”

“…[56 -58] Then, their acetylenes, including phenylacetylene, underwent an addition of tri-n-butyl (trimethylsilyl)tin at room temperature in the presence of a Pd(dba) 2 -P(OEt) 3 combination catalyst affording (Z)-1-aryl-1-(tri-n-butylstannyl)-2-(trimethylsilyl)ethenes 1a-h [32,33] in good isolated yields. The (Z)-silyl(stannyl)ethenes 1b-h prepared in this way were treated with allyl bromide at a preparative scale [33] was exclusively produced. e Five mol% of potassium carbonate with respect to the 1a was added.…”

“…[33] However, upon addition of 5 mol% of potassium carbonate the reaction produced (E)-5-methyl-1-(trimethylsilyl)-2-phenylhexa-1,4-diene 2a-pre in 64% yield. Trimethylsilyl protons of these products in NMR analysis were observed at 0.19 ppm.…”

“…[18] Another is the Migita-Kosugi-Stille type crosscoupling reaction of (Z)-silyl(stannyl)ethenes 1, [19 -33] prepared by the addition of a silyltin to acetylenes, with allylic halides. [22,26] We have already reported the synthesis and characterization of a family of (Z)-silyl(stannyl)ethenes 1 [32,33] and then presented preliminary results for the stereospecific synthesis of (E)-2-aryl-1-silylalka-1,4-dienes using the (Z)-silyl(stannyl)ethenes 1 as a communication. [34] Closely related to the synthesis of allylated vinylsilanes, the reaction with propargyl bromide is also of great interest because of the possibility of producing allenyl vinylsilanes or silylvinyl allenes, and (E)-4-aryl-5-silyl-1,2,4-trienes, which may be important in allene chemistry, [35] particularly in cycloaddition reaction.…”

“…One example is the palladium-catalyzed reaction of 1a with 1-bromo-2-propyne [36] and another is the reaction of (Z)-2-amino-1-silyl-2-stannylethenes with propargyl bromide in the presence of a palladium catalyst. [26] Reported herein are the stereodefined syntheses of novel (E)-vinylsilanes bearing an allyl group or an allenyl group β to silicon with cis-disposition via the cross-coupling of (Z)-silyl(stannyl)ethenes 1 [32,33] with the respective allyl halides or propargyl bromide (Scheme 1).…”