Enynes tetrakis palladium

Pale and coworkers provided the first example of combined desilylation/coupling catalytic for silver. They found that 1-trimethylsilyl-l-alkynes in the presence of tetrakis(triphenylphosphine)palladium, a silver(I) salt, and an activator (potassium carbonate in methanol, or TBAF-3H20) in DMF coupled with vinyl triflates and aryl iodides to give enynes good yields (Scheme 1.66).143,144 Although silver salt was not necessary for reaction when TBAF-3H20 was used for activation of the carbon-silicon bond, a small to significant improvement was observed for all reported... 

Enynes can also be synthesized in excellent yields with high regio- and stereoselectivity by transition metal catalyzed cross-coupling reaction. Thus, ( >l-alkenyl-disiamylboranes react with 1-halo-1-alkynes in the presence of catalytic amount of tetrakis(tripheny]phosphine)palladium to afford conjugated trans enynes (Eq. 100)145). 

ENYNES Di-u-carbonylhexacarbonyl-dicobalt. Tetrakis(triphenyl-phosphine)-palladium. 

ENYNES Diacetatobis(triphenylphosphine)paIladium(II). Tetrakis(triphenylphosphine)-palladium(O). Tetramethylethylenediamine. 1 -TrimethyIsilylpropynylcopper. EPISULFONIUM SALTS Methyl(bismethylthio)sulfonium hexachloroantimonate. EPOXIDES Bromomethyllithium. Diphenyl selenide. Methaneselenol. 

Terminal acetylenes dimerize to conjugated enynes in the presence of catalytic amounts of palladium(II) acetate and the hindered phosphine tris(2,6-dimethoxyphenyl)phosphine. 1-Octyne, for instance, affords the enyne 36 5. Palladium-catalysed condensations of 1-alkynes RC=CH (R=Ph or CH2OH) with vinyl bromide, ( )-2-bromostyrene, iodobenzene and 2-bromopyridine to yield 37, 38, 39, and 40, respectively (Scheme 1), have been reported (see also References 27 and 28). The palladium[tetrakis(triphenylphosphine)]-catalysed alkynylation of 1,1-dichloroethene with terminal alkynes 41 (R = pentyl, 3-chloropropyl, Ph or SiMes) results in the eneynes 42. ... 

ENYNES Di-ji-carbonylhexacar-bonyldicobalt. Lithium diisobutyl-aluminum hydride. Tetrakis(tri-phenylphosphine)palladium(O). 

Efficient and highly stereoselective alkylations of enol phosphates are accomplished with trialkylalanes in the presence of catalytic amounts of tetrakis(triphenylphosphine)palladium if alkenyl- or alkynyl-dialkylalanes are used, the unsaturated group is transferred specifically. Since enol phosphates are readily prepared from ketones, this constitutes a useful method for the transformation of ketones into alkyl-substituted olefins, 1,3-dienes, or 1,3-enynes e.g. Scheme 27). ... 

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