Metalloradical-catalyzed rearrangement of cycloheptatrienyl to benzyl

Abstract

Rh(ttp)(C(7)H(7)) rearranged to give Rh(ttp)(CH(2)Ph) quantitatively at 120 °C in 12 d (ttp = 5,10,15,20-tetratolylporphyrinato dianion). This process is 10(10) faster than for the organic analogue. Mechanistic investigation suggests that a Rh(II)(ttp)-catalyzed pathway is operating.

K2CO3-Promoted Consecutive Carbon–Hydrogen and Carbon–Carbon Bond Activation of Cycloheptane with Rhodium(III) Porphyrin Complexes: Formation of Rhodium Porphyrin Cycloheptyl and Benzyl

“…Added K 2 CO 3 did not change the k obs value (Table , entry 3) and therefore does not catalyze the reaction. However, the k obs value increases with higher concentration of added Rh 2 (ttp) 2 (Table , entries 4 and 5) as reported . A 10-fold increase of [Rh 2 (ttp) 2 ] produces a 3-fold enhancement of the rate, supporting a half-order dependence on Rh 2 (ttp) 2 or first-order dependence on Rh(ttp), thus validating the Rh(ttp)-catalyzed isomerization.…”

“…Initially, cycloheptane was found to react with Rh(ttp)Cl ( 1 ) (Figure ) to give Rh(ttp)(cycloheptyl) ( 2 ) in 18% yield as the sole CHA product, while 70% of Rh(ttp)Cl was recovered (Scheme ). However, when K 2 CO 3 (10 equiv) was added, ,,, Rh(ttp)(cycloheptyl) ( 2 ), Rh(ttp)H ( 4 ), and surprisingly the CCA product Rh(ttp)Bn ( 3 ) were formed in 30, 30, and 25% yields, respectively.…”

“…Rh(ttp)(cycloheptyl) further undergoes Rh II (ttp)-catalyzed dehydrogenation to yield Rh(ttp)(cycloheptatrienyl), which further isomerizes into Rh(ttp)Bn via a Rh II (ttp)-catalyzed skeletal rearrangement. We have communicated that the metalloradical-catalyzed isomerization is 10 10 times faster than the analogous organic isomerization of cycloheptatriene into toluene . We now report the full scope of the K 2 CO 3 -promoted CHA and CCA of cycloheptane with Rh(ttp)Cl.…”

Gold(I) Carbenes by Retro-Buchner Reaction: Generation and Fate

“… 51 In addition, diethyl maleate (14% yield) was formed, presumably by a dimetization of a Pd(II) carbene formed by a retro-Buchner process. 52 Formation of benzyl-Rh(II) from cycloheptatrienyl-Rh(I) occurs by a metalloradical process. Cycloheptatriene has also been found to react on the metal carbide W(100)-(5 × 1)-C surface to generate benzene at 600 K, 53 whereas (tricarbonyl)(tropylium)chromium perchlorate forms benzene(tricarbonyl)chromium by reaction with sodium cyclopentadienide or diethyl sodium malonates by an unknown mechanism.…”

A hybrid carbocyclic/N-heterocyclic carbene ligand

“…Of such Z 1 -bound cycloheptatrienyl complexes only three examples in transition metal chemistry and some more involving tin have been crystallographically characterised so far. [23][24][25][26][27][28][29][30] A Z 1 -cycloheptatrienyl complex has also been proposed as a short-lived intermediate in the reaction of CHT complexes with nucleophiles. 20 In agreement with previous reports, the seven-membered ring adopts a distinct boat-conformation as required by the tetrahedral environment of the alkyl-bound carbons C1 and C23, which feature bond lengths of Pd1-C1 = 2.023(7) Å, C1-C2 = 1.482(15) Å, C1-C7 = 1.496(12) Å, Pd2-C23 = 2.008(9) Å, C23-C24 = 1.500 (14) Å and C23-C29 = 1.489(12) Å.…”