: 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

저작근 근전도에 관한 정상교합자와 ii급 부정교합자의 비교 연구

Advances in hypervalent iodine chemistry have put the field on the precipice of a second golden age; the first being pioneered in the 1990s. During that period, C–C bond forming reactions would be published but rarely with the intended goal of developing a C–C bond forming methodology. More recently, the development of hypervalent iodine-guided electrophilic substitution, arylations using hypervalent iodine, and photoredox reactions with hypervalent iodine have shown great progress in the area of C–C bond formation.

Hypervalent iodine reactions utilized in carbon–carbon bond formations

We report a general visible-light-mediated strategy that enables the construction of complex C(sp3)-rich N-heterospirocycles from feedstock aliphatic ketones and aldehydes with a broad selection of alkene-containing secondary amines. Key to the success of this approach was the utilization of a highly reducing Ir-photocatalyst and orchestration of the intrinsic reactivities of 1,4-cyclohexadiene and Hantzsch ester. This methodology provides streamlined access to complex C(sp3)-rich N-heterospirocycles displaying structural and functional features relevant to fragment-based lead identification programs.

/pdf/streamlined-synthesis-of-c-sp3-rich-n-heterospirocycles-4yqoejiq21.pdf

Streamlined synthesis of C(sp3)-Rich N-Heterospirocycles enabled by visible-light-mediated photocatalysis

Recent Advances in Intramolecular Metal-Free Oxidative C–H Bond Aminations Using Hypervalent Iodine(III) Reagents

Hypervalent iodine reagents have been developed as highly valuable reagents in synthetic organic chemistry during the past few decades. These reagents have been identified as key replacements of various toxic heavy metals in organic synthesis. Various synthetically and biologically important scaffolds have been developed using hypervalent iodine reagents either in stoichiometric or catalytic amounts. In addition, hypervalent iodine reagents have been employed for the synthesis of spirocyclic scaffolds via dearomatization processes. In this review, various approaches for the synthesis of spirocyclic scaffolds using hypervalent iodine reagents are covered including their stereoselective synthesis. Additionally, the applications of these reagents in natural product synthesis are also covered.

https://www.beilstein-journals.org/bjoc/content/pdf/1860-5397-14-152.pdf

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents.

Hypervalent iodine compounds as environmentally friendly and relatively inexpensive reagents have properties similar to transition metals. They are employed as alternatives to transition metal catalysts in organic synthesis as mild, nontoxic, selective and recyclable catalytic reagents. Formation of C-N, C-O, C-S, C-F and C-C bonds can be seamlessly accomplished by hypervalent iodine catalysed oxidative functionalisations. The aim of this review is to highlight recent developments in the utilisation of iodine(III) and iodine(V) catalysts in the synthesis of a wide range of organic compounds including chiral catalysts for stereoselective synthesis. Polymer-, magnetic nanoparticle- and metal organic framework-supported hypervalent iodine catalysts are also described.

Progress in organocatalysis with hypervalent iodine catalysts.

Hypervalent iodine compounds are valuable and versatile reagents in synthetic organic chemistry, generating a diverse array of useful organic molecules. Owing to their non-toxic and environmentally friendly features, these reagents find potential applications in various oxidative functionalization reactions. In recent years, the use of hypervalent iodine reagents in palladium-catalyzed transformations has been widely studied as they are strong electrophiles and powerful oxidizing agents. For instance, extensive work has been carried out in the field of C-H bond functionalization via Pd-catalysis using hypervalent iodine reagents as oxidants. In addition, nowadays, iodine(III) reagents have been frequently employed as arylating agents in Pd-catalyzed C-H arylation or Heck-type cross-coupling reactions. In this review, recent advancements in the area of palladium-catalyzed oxidative cross-coupling reactions using hypervalent iodine reagents are summarized in detail.

/pdf/hypervalent-iodine-reagents-in-palladium-catalyzed-oxidative-531zanaqh7.pdf

Hypervalent Iodine Reagents in Palladium-Catalyzed Oxidative Cross-Coupling Reactions.

A metal-free, ultrasound-assisted approach for the synthesis of highly functionalized 2-tetralones in high yields is described. The process involves ring transformation of 2H-pyran-2-ones with the spirocyclic ketone 1,4-cyclohexandione monoethylene ketal to yield spiro­cyclic ketals and subsequent acid-mediated hydrolysis. This protocol is free from any organometallic reagents, is economical and tolerates a wide range of functional groups.

/pdf/a-metal-free-approach-for-the-synthesis-of-2-tetralones-via-f0vsfxslvu.pdf

Samata E. Shetgaonkar

Papers

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents.

Progress in organocatalysis with hypervalent iodine catalysts.

Hypervalent Iodine Reagents in Palladium-Catalyzed Oxidative Cross-Coupling Reactions.

A Metal-Free Approach for the Synthesis of 2-Tetralones via Carbanion-Induced Ring Transformation of 2H-Pyran-2-ones

Ultrasound-assisted one pot synthesis of polysubstituted meta-terphenyls using ring transformation strategy