: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Synergistic catalysis, a type of plural catalysis which utilizes at least two different catalysts to enable a reaction between two separately activated substrates, has unlocked a plethora of previously unattainable transformations and novel chemical reactivity. Despite the appreciable utility of synergistic catalysis, specific examples involving two transition metals have been limited, as ensuring a judicious choice of reaction parameters to prevent deactivation of catalysts, undesirable monocatalytic event(s) leading to side products, or premature termination and other potentially troublesome outcomes present a formidable challenge. Excluding those driven by photocatalytic mechanisms, this review will highlight the reported examples of reactions that make use of two simultaneous catalytic cycles driven by two transition metal catalysts.

Synergistic Dual Transition Metal Catalysis

The introduction of a trifluoromethyl (CF3) group can dramatically improve a compound’s biological properties. Despite the well-established importance of trifluoromethylated compounds, general methods for the trifluoromethylation of alkyl C–H bonds remain elusive. Here we report the development of a dual-catalytic C(sp3)–H trifluoromethylation through the merger of light-driven, decatungstate-catalysed hydrogen atom transfer and copper catalysis. This metallaphotoredox methodology enables the direct conversion of both strong aliphatic and benzylic C–H bonds into the corresponding C(sp3)–CF3 products in a single step using a bench-stable, commercially available trifluoromethylation reagent. The reaction requires only a single equivalent of substrate and proceeds with excellent selectivity for positions distal to unprotected amines. To demonstrate the utility of this new methodology for late-stage functionalization, we have directly derivatized a broad range of approved drugs and natural products to generate valuable trifluoromethylated analogues. Preliminary mechanistic experiments reveal that a ‘Cu–CF3’ species is formed during this process and the critical C(sp3)–CF3 bond-forming step involves the copper catalyst. Despite the importance of trifluoromethylated compounds, direct catalytic methods for the conversion of C(sp3)–H bonds into the corresponding C(sp3)–CF3 analogues have remained elusive. This transformation has now been achieved by the merger of copper catalysis with decatungstate photocatalysis, enabling the C(sp3)–H trifluoromethylation of abundant feedstocks, natural products and pharmaceuticals.

The merger of decatungstate and copper catalysis to enable aliphatic C(sp 3)–H trifluoromethylation

A versatile method for the rapid synthesis of diverse enantiomerically enriched lactones has been developed based on Cu-catalyzed enantioselective radical oxyfunctionalization of alkenes. The scope of this strategy encompasses a series of enantioselective difunctionalization reactions: oxyazidation, oxysulfonylation, oxyarylation, diacyloxylation, and oxyalkylation. These reactions provide straightforward access to a wide range of useful chiral lactone building blocks containing tetrasubstituted stereogenic centers, which are hard to access traditionally.

Versatile Enantioselective Synthesis of Functionalized Lactones via Copper-Catalyzed Radical Oxyfunctionalization of Alkenes.

A novel asymmetric radical aminotrifluoromethylation of alkenes has been developed for the first time, providing straightforward access to densely functionalized CF3-containing azaheterocycles bearing an α-tertiary stereocenter with excellent enantioselectivity. The key to success is not only the introduction of a Cu(I)/chiral phosphoric acid dual-catalytic system but also the use of urea with two acidic N–H as both the nucleophile and directing group. The utility of this method is illustrated by facile transformations of the products into other important compounds useful in organic synthesis and medicinal chemistry.

A Dual-Catalytic Strategy To Direct Asymmetric Radical Aminotrifluoromethylation of Alkenes

The mechanisms of trifluoromethylation with hypervalent iodine trifluoromethylation reagent (Togni’s reagent 1) have been comprehensively studied by density functional theory (DFT) calculations. The results show that there are two general reaction modes for reagent 1: (I) Mode-A, acting as a CF3• free radical source. When one-electron reductants are available in the reaction system, such as CuI, FeII, TEMPONa, or electron-rich lithium enolate, 1 will be reduced via single-electron transfer (SET) and give out CF3• free radical concertedly. In the CuI-catalyzed trifluoromethylation of terminal olefins, CuI promotes the homo-cleavage of the F3C–I bond in 1 via SET to produce CuII species and CF3• free radical. Then the CF3• free radical attacks the olefin, leading to trifluoromethyl alkyl radical intermediate. Subsequently, the CuII species act as a one-electron oxidant oxidizing the alkyl radical to carbocation intermediate, and the following deprotonation leads to the final product. Other mechanisms, such ...

General Reaction Mode of Hypervalent Iodine Trifluoromethylation Reagent: A Density Functional Theory Study

A Cu-mediated preparation of 2-substitiuted pyrazolo[1,5-a]pyridines from N-benzoylpyridinium imides and terminal alkynes is described using stoichiometric Cu(OAc)2 as both the mediator and the oxidant. Extensive DFT calculations suggest a Cu(III) intermediate via disproportionation of Cu(II).

From N-benzoylpyridinium imides to pyrazolo[1,5-a]pyridines: a mechanistic discussion on a stoichiometric Cu protocol.

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General Reaction Mode of Hypervalent Iodine Trifluoromethylation Reagent: A Density Functional Theory Study

From N-benzoylpyridinium imides to pyrazolo[1,5-a]pyridines: a mechanistic discussion on a stoichiometric Cu protocol.