Activation of Alkyl Halides via a Silver‐Catalyzed Carbene Insertion Process.

Abstract

2003 Halogenated carboxylic acids and esters Halogenated carboxylic acids and esters P 0260 Activation of Alkyl Halides via a Silver-Catalyzed Carbene Insertion Process. -A new silver complex catalyzes the formation of aliphatic carbon-halogen bond activation products under mild conditions. The presence of β-hydrogen atoms on the alkyl halide leads to net hydrogen halide addition to the carbene with concomitant formation of an alkene. -(DIAS*, H. V. R.; BROWNING, R. G.; POLACH, S. A.; DIYABALANAGE, H. V. K.; LOVELY*, C. J.; J. Am. Chem. Soc. 125 (2003) 31, 9270-9271; Dep. Chem. Biochem., Univ. Tex., Arlington, TX 76019, USA; Eng.) -S. Adam 45-064

Elucidation of the Reaction Mechanism of C2 + N1 Aziridination from Tetracarbene Iron Catalysts

“…An iron imide could be formed through initial binding of the α-nitrogen or γnitrogen of the azide to the catalyst, so both intermediates were investigated. [59][60][61][62][63] Similar to Co and Ru systems, the energy of the α-bound intermediate was lower than that of the γbound case. 39,40,64 The free energy of activation for formation of the imide from the αbound intermediate was calculated to be ΔG ‡ = 9.9 kcal/mol, suggesting that the formation of imide via this route is highly facile at room temperature (rt) (no route to an imide was found for the γ-bound case).…”

Reaction Chemistry of Silver(I) Trifluoromethanesulfonate Complexes of Nitrogen-Confused C-Scorpionates

“…[fac-Mn(CO) 3 ( H L*)](OTf) (7). A mixture of 0.158 g (0.299 mmol) of 3a and 0.0822 g (0.299 mmol) of Mn(CO) 5 Br gave 0.151 g (85%) of 7 as a yellow solid.…”

“…It was learned in the late 1990s that silver reduction could be slowed by increasing the steric bulk on the pyrazolyls, by removing B−H bonds, and/or by introducing electron-withdrawing groups on the pyrazolyl rings. 6 Intensified interest in silver(I) scorpionates began with early reports from the Dias group that showed that the fluorinated scorpionate complex, AgTp (CF 3 ) 2 , was a competent catalyst for carbene insertion into C−halogen bonds, 7 aromatic CC bonds (Buchner reaction), 8 and aliphatic C−H bonds. 9 Further inciting interest were reports from the Peŕez group that showed that AgTp x complexes catalyzed a variety of transformations 6 such as carbene insertion into alkane C−H bonds, 10 Si−H bonds, 11 and C−X (X = Cl, Br) bonds 12 or were used for the cross-coupling of diazo compounds.…”

Silver-catalyzed site-selective C(sp3)−H benzylation of ethers with N-triftosylhydrazones

“…In good agreement with previous reports 20 – 26 , dialkyl ethers afforded single α-C–H insertion products in high yields, while benzyl ethers reacted exclusively at the benzylic C–H bonds ( 51 – 58 ). For methyl 4-chlorobutyl ether, insertion occurred into the C–H bonds α- to the ether oxygen; no reaction at or adjacent to the C–Cl bond was observed ( 59 ) 54 . Excitingly, various saturated cyclic ethers, such as tetrahydrofuran ( 60 ), 1,3-dihydroisobenzofuran ( 61 ), 1,3-dioxolane ( 62 ), tetrahydropyran ( 63 ), and isochromane ( 64 ), smoothly furnished the corresponding benzylated oxacycles in good to excellent yields.…”