Alkenylbismuthonium salts

Scheme 3 shows the conceivable reaction sites of alkenylbismuthonium salts, alkynylbismuthonium salts, bismuth ylides, and bismuth imides in carbon-carbon and carbon-heteroatom bond forming reactions. In the initial step, nucleophiles (Nu) attack the positively charged bismuth(V) center, a-proton or (3-carbon (Scheme 3a, b) whereas electrophiles (El) attack the negatively charged a-carbon or a-nitrogen (Scheme 3c, d). Usually, the resulting bismuth(V) intermediates... 

Scheme 3 Reaction sites of organobismuth(V) reagents in C-C and C-X bond forming reactions (a) alkenylbismuthonium salt (b) alkynylbismuthonium salt (c) bismuth ylide (d) bismuth imide. Nu nucleophile, B base, El electrophile...

Scheme 4 Alkenylation of enolates with alkenylbismuthonium salts [38]...

The alkenylation of phenols also proceeds smoothly in the presence of TMG (Scheme 6). The major products are not aryl alkenyl ethers but a-alkenylated cyclohexa-2,4-dienones. That is, C-alkenylation occurs exclusively at the ortho position of phenols. When 2-naphthol reacts with two equivalents of the alkenylbismuthonium salt, a,a-dialkenyl ketone is obtained in good yield as the sole alkenylated product. 

Scheme 7 Cyclopropanation of styrenes with an alkenylbismuthonium salt [37]...

Oxoalkylbismuthonium salts react with a sodium salt of dibenzoylmethane to alkylate the active methylene carbon [304]. Treatment of a mixture of Ph3BiF2 and allyltrimethylsilane with lii, -O Hl, in the presence of excess electron-rich arenes yields allylated arenes via the Friedel-Crafts reaction (Scheme 14.149) [305]. The action of tBuOK on a mixture of alkenylbismuthonium salt and styrenes gives al-kylidenecyclopropanes in high yield (Scheme 14.150) [306]. Michael addition of sodium p-toluenesulfinate to a 1-hexynylbismuthonium salt results in the formation of 3-methyl-l-tosylcyclopentene [307]. 

Cyclopropanation of styrene using alkenylbismuthonium salt 300 Deprotection of 5,5-acetals to carbonyl compounds 391 Diothioacetalization of carbonyl compounds with thiols 427 Friedel-Crafts acylation with Bi(OTf>3 as catalyst 408 Glycosylation of 1-glycosyl dimethyl phosphite with alcohols 425 Oxidation of... 

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