Regio‐ and Stereoselective Generation of Alkenylindium Compounds from Indium Tribromide, Alkynes, and Ketene Silyl Acetals

Abstract

InBr(3) promotes the addition of ketene silyl acetals to monosubstituted alkynes to afford 2,2-disubstituted alkenylindium compounds in high regio- and stereoselectivity (see scheme). In addition, the alkenylindium derivatives have been subsequently coupled with iodobenzene in the presence of a palladium catalyst.

Indacyclopentadienes and Aromatic Indacyclopentadienyl Dianions: Synthesis and Characterization

“…The length of the InÀC(sp 2 )b ond is 2.161(2) ,w hich falls in the range of the reported InÀC(sp 2 ) bond lengths. [17] The molecular structures of 3a,b were also confirmed by Xray crystallographic analysis( for details, see the Supporting Information). The structure of 3b is given in Figure 3.…”

Synthesis of (Z)‐β‐(Carbonylamino)alkenylindium through Regioselective anti‐Carboindation of Ynamides and Its Transformation to Multisubstituted Enamides

“…[6] We recently reported intermolecular anti-carbometalations of carbon-carbon triple bonds by using silylatedn ucleophiles and metal salts, such as InBr 3 ,G aBr 3 ,A lBr 3 ,B iBr 3 ,a nd ZnBr 2 . [7] Therefore, we assumedo ur strategy could achieve anti-carbometalation of ynamides. Here, we report the anti-carbometalation of ynamides by using InBr 3 and silyl ketene acetals to synthesize (Z)-b-(carbonylamino)alkenylindiums(Scheme 1c).First, we surveyed metal halides fort he carbometalation of N-ethynylpyrrolidone (1a)b yu sing the silyl ketene acetal 2a (Table 1).…”

“…On the other hand, the use of InCl 3 resultedi nayield of only 66 %( Ta ble 1, entry 3). ZnBr 2 , ZnI 2 ,G aBr 3 ,G aI 3 ,a nd BiBr 3 afforded 3aa in moderate yields ( Table 1, entries [4][5][6][7][8]. Other Lewisa cids, such as CuBr and AlBr 3 were not effective ( Table 1, entries 9a nd 10).…”

Regio‐ and Stereoselective Carbobismuthination of Alkynes

“…In addition, the present study was an effort to expand carbometalation based on this concept, which has recently been reported for carboindation and carbogallation. [8,9] The present reaction system requires only a simple mixture of BiBr 3 , an alkyne, and a ketene silyl acetal to produce an alkenylbismuth bearing an ester moiety with high stereo-and regioselectivity.…”

“…It is similar to the mechanism proposed for carbometallation using indium and gallium trihalides, with exception of the transmetalation between BiBr 3 and ketene silyl acetal 9. [8,9] The interaction between BiBr 3 and alkyne 8 results in a positive charge at the internal carbon of the triple bond, which is stabilized by the R 1 group. [11] Then, the internal carbon is attacked by ketene silyl acetal 9 anti to BiBr 3 to furnish monoalkenylbismuth 11 with regio-and stereoselectivity.…”