1,1,3,3-Tetramethylbutyl isocyanide

The ( )-vinylsilane 151 was prepared by treatment of the silylstannation product 150 with hydrogen iodide[75] and the silylzincation product with water[70]. The silylstannylation of 1-ethoxyacetylene proceeds at room temperature using Pd(OAc)i and 1,1,3,3-tetramethylbutyl isocyanide regioselec-tively and an Si group is introduced at the ethoxy-bearing carbon. Subsequent Cul- and Pd-catalyzed displacement of the stannyl group in the product 152 with allyl halide, followed by hvdrolvsis, affords the acylsilane 153[79],... 

Addition reactions of the Si-Si cr-bonds of disilanes 121, 131, and 133 to the C=C bonds of various arynes were found to be promoted by a palladium-1,1,3,3-tetramethylbutyl isocyanide complex. Diverse 1,2-disilylated arenes 130, 132, and 134 were obtained from five-membered and benzo-condensed six-membered cyclic disilanes (Equations 21-23). The H, 13C, and z9Si NMR spectroscopic data as well as X-ray crystallographic analysis were used to confirm the above structures <20050M156>. 

Palladium(II) acetate-1-Octyl isocyanide (1,1,3,3-tetramethylbutyl isocyanide). 

Borylsilylation of 1-octyne with 120 provided the alkenylboronate 121 in high yield using Pd(OAc)2 and bulky isocyanide (1,1,3,3-tetramethylbutyl isocyanide, XVll-6) as a ligand. The product 121 was subjected to Suzuki coupling catalyzed by PdCBCdppf) [36], Under similar conditions, no intermolecular bis-silylation of internal alkynes took place. However, intramolecular bis-silylation of disilanyl ether of homopropargylic alcohol proceeded smoothly with 5-exo-dig cyclization [36a]. 

Related Reagents. 7V,7V Diethylaminoacetonitrile Dimethyldithiocarbamoylacetonitrile (4a/ )-(4aa, 7Q, 8a )-Hexa-hydro-4,4,7-trimethyl-4i l,3-benzoxathiin 2-Lithio-l,3-dithi-ane Nitromethane 1,1,3,3-Tetramethylbutyl Isocyanide p-Tolylsulfonylmethyl Isocyanide 2-(Trimethylsilyl)thiazole. 

In spite of the fact that compounds having Si—bonds (silylboranes) were already prepared in the early 1960s,somewhat surprisingly, transition-metal-catalyzed reaction of the silylboration had not been reported until 1996. Suginome, Nakamura, and Ito have found that silaboration of acetylenes proceeds smoothly in the presence of a catalyst Pd(OAc)2/t-octyl NC. Under reflux in toluene, addition of the Si—bonds across the carbon-carbon triple bond of 1-octyne took place in the presence of the catalyst prepared from 2 mol % of Pd(OAc)2 and 30 mol % of 1,1,3,3-tetramethylbutyl isocyanide (Scheme 21). 

Intermolecular Disilylation of Alkynes. Intermolecular disilylation of 1-alkynes (14) are promoted using palladium(II) acetate-1,1,3,3-tetramethylbutyl isocyanide at reflux or Pd(dba)2-P(OCH2)3CEt at 120 °C to give (Z)-l,2-... 

Aliphatic organomagnesium or organolithium reagents add to 1,1,3,3-tetramethylbutyl isocyanide to give the corresponding metallo-aldimine (150), another acyl carbanion equivalent, which reacts with a range of electrophiles in the normal manner. 

TetramethylbutylIsocyanide Walborsky and coworkers reported the first synthesis of 1,1,3,3-tetramethylbutyl isocyanide (TMBIC, Iza) in 1969 [92], It can be readily synthesized by the dehydration of corresponding for-mamide 8m using a DMF (anhydrous) solution of thionyl chloride (which generates chlorodimethylforminium chloride in situ) and sodium carbonate (Scheme 7.80). TMBIC is commonly known as Walborsky s CIC. 

Tetramethylbutyl Isocyanide Blackburn and coworkers have utilized Walborsky s CIC Iza to synthesize 2-aminoimidazo[l,2-fl]pyridines (364) [122]. The 3CR of 2-aminopyridine (6g), 4-methoxybenzaldehyde (9z), and CIC Iza provided 363. The 1,1,3,3-tetrametliylbutyl group can be cleaved by using either a 1 1 solution of 12 N HCl/MeOH or a TFA/CH2CI2 mixture to obtain the desired product 364 (Scheme 7.111). This method can also be used for solid-phase synthesis. 

The addition of alkyllithiums to the electron-rich terminal carbon atom of sterically hindered isocyanides has been extensively studied by Henry Walborsky et 1,1,3,3-Tetramethylbutyl isocyanide and jec-butyllithium combine to form an... 

To palladium acetate (1.8 mg, 7.8 //mol) placed in a Schlenk-type tube under a nitrogen atmosphere is added 1,1,3,3-tetramethylbutyl isocyanide (16.8 mg, 0.12 mmol) under stirring at rt. >eep red color is observed immediately, indicating the formation of active palladium(0)-isonitrile catalyst. To the mixture successively added at rt are toluene (0.1 mL), (dimethylphenylsilyl)(pinacolato)borane (102 mg, 0.39 mmol), and 3-(/er/-butyldimethylsilyloxy)-l-propyne (91 mg, 0.53 mmol). The resulting mixture is heated to reflux for 1-4 h, then cooled down to rt, and finally subjected to a short column chromatography on silica gel (diethyl ether) to remove the catalyst. Further purification by bulb-to-bulb distillation of the crude product gives the title compound in 83% 3deld. 

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