Allyl cyanides are found to add across alkynes in the presence of a nickel catalyst prepared from Ni(cod)2 and P(4-CF3-C6H4)3 in situ to give variously functionalized di- or trisubstituted acrylonitriles in highly stereoselective manners possibly via a pi-allylnickel species as an intermediate. alpha-Siloxyallyl cyanides also react at the gamma-position of a cyano group with both internal and terminal alkynes having various functional groups to give silyl enol ethers, which give the corresponding aldehydes or ketones upon hydrolysis.

Aryl cyanides add to norbornene and norbornadiene under nickel catalysis to give (2R*,3S*)-3-aryl-2-cyanobicyclo[2.2.1]heptanes and (2R*,3S*)-3-aryl-2-cyanobicyclo[2.2.1]hept-5-enes in good yields with a general substrate scope. On the other hand, the reaction of an aryl cyanide with triethoxy(vinyl)silane gives a Heck-type arylation product, suggesting the arylnickelation pathway in the catalytic cycle.

No abstract

The carbometalation reaction of alkynes allows the simultaneous, stereoselective formation of both carbon-carbon and carbon-metal bonds and provides us with a highly powerful tool for the synthesis of novel organometallic reagents that contain multisubstituted ethenes.[1] In particular, the palladium-or nickel-catalyzed carbostannylation of alkynes affords highly functionalized alkenylstannanes, which undergo various chemoselective transformations, such as the Kosugi-Migita-Stille coupling reaction. [2,3] Alkynyl, allyl, and acylstannanes which reportedly undergo oxidative addition of a CÀSn bond to palladium(0) and nickel(0) complexes, [4] are successfully applied to the carbostannylation reaction, whereas aryl-, alkenyl-, and alkylstannanes are found to be sluggish probably because of their low potential for oxidative addition to low-valent transition-metal complexes.[5, 6] Herein, we report the first examples of aryl-, alkenyl-, and alkylstannylations of alkynes through the decarbonylative addition of acylstannanes [7] catalyzed by Pd/C [Eq.(1)].[8]During our investigation of the acylstannylation of alkynes, we observed that the reaction of benzoyl-(tributyl)stannane (1 a) with propargyl acetate (2 a; 2.0 equiv) using 2.5 mol % of [Pd 2 (dba) 3 ] (dba = dibenzylideneacetone) in Bu 2 O [9] at 50 8C for 12 h gave (E)-2-phenyl-1-(tributylstannyl)propen-3-yl acetate (3 a) in 29 % yield, as estimated by 119 Sn NMR spectroscopic analysis (Table 1, entry 1). The yield increased to 44 % with propargyl benzoate

The carbometalation reaction of alkynes allows the simultaneous, stereoselective formation of both carbon-carbon and carbon-metal bonds and provides us with a highly powerful tool for the synthesis of novel organometallic reagents that contain multisubstituted ethenes.[1] In particular, the palladium-or nickel-catalyzed carbostannylation of alkynes affords highly functionalized alkenylstannanes, which undergo various chemoselective transformations, such as the Kosugi-Migita-Stille coupling reaction. [2,3] Alkynyl, allyl, and acylstannanes which reportedly undergo oxidative addition of a CÀSn bond to palladium(0) and nickel(0) complexes, [4] are successfully applied to the carbostannylation reaction, whereas aryl-, alkenyl-, and alkylstannanes are found to be sluggish probably because of their low potential for oxidative addition to low-valent transition-metal complexes.[5, 6] Herein, we report the first examples of aryl-, alkenyl-, and alkylstannylations of alkynes through the decarbonylative addition of acylstannanes [7] catalyzed by Pd/C [Eq.(1)].[8]During our investigation of the acylstannylation of alkynes, we observed that the reaction of benzoyl-(tributyl)stannane (1 a) with propargyl acetate (2 a; 2.0 equiv) using 2.5 mol % of [Pd 2 (dba) 3 ] (dba = dibenzylideneacetone) in Bu 2 O [9] at 50 8C for 12 h gave (E)-2-phenyl-1-(tributylstannyl)propen-3-yl acetate (3 a) in 29 % yield, as estimated by 119 Sn NMR spectroscopic analysis (Table 1, entry 1). The yield increased to 44 % with propargyl benzoate