62587-07-9Relevant articles and documents
B(C6F5)3-Catalyzed Hydrosilylation of Vinylcyclopropanes
He, Tao,Long, Peng-Wei,Oestreich, Martin
supporting information, p. 7383 - 7386 (2020/10/12)
A hydrosilylation of vinylcyclopropanes (VCPs) catalyzed by the strong boron Lewis acid B(C6F5)3 is reported. For the majority of VCPs, little or no ring opening of the cyclopropyl unit is observed. Conversely, for VCPs with bulky R groups, such as ortho-substituted aryl rings or branched alkyl residues, ring opening is the exclusive reaction pathway. This finding is explained by the thwarted hydride delivery to a sterically shielded, β-silicon-stabilized cyclopropylcarbinyl cation intermediate.
Continuous flow synthesis of ketones from carbon dioxide and organolithium or grignard reagents
Wu, Jie,Yang, Xiaoqing,He, Zhi,Mao, Xianwen,Hatton, T. Alan,Jamison, Timothy F.
supporting information, p. 8416 - 8420 (2014/08/18)
We describe an efficient continuous flow synthesis of ketones from CO 2 and organolithium or Grignard reagents that exhibits significant advantages over conventional batch conditions in suppressing undesired symmetric ketone and tertiary alcohol byproducts. We observed an unprecedented solvent-dependence of the organolithium reactivity, the key factor in governing selectivity during the flow process. A facile, telescoped three-step-one-flow process for the preparation of ketones in a modular fashion through the in-line generation of organometallic reagents is also established.
DFT evidence for a stepwise mechanism in the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals
Bietti, Massimo,Ercolani, Gianfranco,Salamone, Michela
, p. 4515 - 4519 (2008/02/05)
(Chemical Equation Presented) Hybrid DFT calculations of the potential energy surface (PES) relative to the O-neophyl rearrangement of a series of ring-substituted 1,1-diarylalkoxyl radicals have been carried out at the UB3LYP/6-31G(d) level of theory. On the basis of the computational data, the rearrangement can be described as a consecutive reaction of the type a ? b → c (see above graphic), and the steady-state approximation could be applied in all cases to the intermediate b. The first-order rearrangement rate constants [kobs = k1k2/(k-1 + k 2)] were thus obtained from the computed activation free-energies and were compared with the experimental rate constants measured previously in MeCN solution by laser flash photolysis. An excellent agreement is observed along the two series, which strongly supports the hypothesis that the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals proceeds through the formation of the reactive 1-oxaspiro [2,5]octadienyl radical intermediate. This is in contrast to previous hypotheses that involve either a long-lived intermediate or the absence of this intermediate along the reaction path. The calculated rearrangement free-energies decrease upon going from the methoxy-substituted radical (ΔG° = -16.4 kcal·mol-1) to the nitro-substituted one (ΔG° = -21.8 kcal·mol-1), which follows a trend that is similar to the one observed for the C Ar-O bond dissociation enthalpies (BDEs) of ring-substituted anisoles. This evidence indicates that in the O-neophyl rearrangement the effect of ring substituents on the strength of the newly formed CAr-O bond plays an important role.
