Determination of the 13C NMR chemical shifts in an a2u type iron(III) porphyrin cation radical

The 13C NMR chemical shifts of all the carbons in an a2u type iron(III) porphyrin radical cation, [Fe(TPP)Cl]+, have been determined for the first time by the titration method as well as by the chemical shift correlation; they are 2230, 1050, and -1910 ppm for the alpha-pyrrole, beta-pyrrole, and meso carbon atoms, respectively.     

An effective method to use ionic liquids as reaction media for asymmetric reduction by Geotrichum candidum

An effective method was developed to use an enzyme in ionic liquids; the asymmetric reduction of ketones by Geotrichum candidum in ionic liquids proceeded smoothly with excellent enantioselectivity when the cell was immobilized on water-absorbing polymer containing water, while the reaction without the polymer did not proceed.     

Potential energy surfaces and nonadiabatic transitions in the asymptotic regions of ICN photodissociation to study the interference effects in the F1 and F2 spin-rotation levels of the CN products

One of the most spectacular yet unsolved problems for the ICN -band photodissociation is the non-statistical spin-rotation F₁ = N + 1/2 and F₂ = N − 1/2 populations for each rotation level N of the CN fragment. The F₁/F₂ population difference function f(N) exhibits strong N and λ dependences with an oscillatory behavior. Such details were found to critically depend on the number of open-channel product states, namely, whether both I (²P_3/2) and I (²P_1/2) are energetically available or not as the dissociation partner. First, in the asymptotic region, the exchange and dipole-quadrupole inter-fragment interactions were studied in detail. Then, as the diabatic basis, we took the appropriate symmetry adapted products of the electronic and rotational wavefunctions for the F₁ and F₂ levels at the dissociation limits. We found that the adiabatic Hamiltonian exhibits Rosen–Zener–Demkov type nonadiabatic transitions reflecting the switch between the exchange interaction and the small but finite spin-rotation interaction within CN at the asymptotic region. This non-crossing type nonadiabatic transition occurs with the probability 1/2, that is, at the diabatic limit through a sudden switch of the quantization axis for CN spin S from the dissociation axis to the CN rotation axis N . We have derived semiclassical formulae for f(N) and the orientation parameters with a two-state model including the 3A′ and 4A′ electronic states, and with a four-state model including the 3A′ through 6A′ electronic states. These two kinds of interfering models explain general features of the F₁ and F₂ level populations observed by Zare's group and Hall's group, respectively. © 2018 Wiley Periodicals, Inc.     

Lannotinidines A-G, new alkaloids from two species of Lycopodium

Seven new Lycopodium alkaloids, lannotinidines A-G (1-7), have been isolated from the club moss Lycopodium annotinum and L. annotinum var. acrifolium. Stereochemistry of 1-7 was elucidated by combination of NOESY correlations and chemical transformation. Lannotinidines B-E (2-5) elevated NGF mRNA expression.     

A highly cis-selective synthesis of 2-ethynylaziridines by intramolecular amination of chiral bromoallenes: improvement of stereoselectivity based on the computational investigation

The base-mediated intramolecular amination of bromoallenes having an axial chirality is described. The treatment of (4S,aR)-4-alkyl-4-[N-(arylsulfonyl)amino]-1-bromobuta-1,2-dienes with NaH in DMF affords 2,3-cis-2-ethynylaziridines in good to excellent selectivity (2,3-cis:trans = 92:8-99:1). The reaction of (4S,aS)-bromoallenes with NaH/DMF also gives 2,3-cis-2-ethynylaziridines selectively (79:21-91:9). These experimental results have been rationalized by B3LYP density functional calculations together with the 6-31+G(d) basis set and the Onsager solvation model. The transition structures for cis-aziridine formation of both (4S,aR)- and (4S,aS)-bromoallenes in DMF are favored over the corresponding trans transition structures by 4.35 and 1.41 kcal/mol, respectively. Furthermore, the calculations predicted that a less polar solvent gives higher cis selectivity for (4S,aS)-bromoallenes. In fact, improvement of the cis selectivity to 99:1 has been realized by using a less polar solvent such as THF. The cyclization of bromoallenes bearing a beta- or gamma-amino group also affords four- and five-membered azacycles in a highly cis-selective manner.     

Benzyne-induced ring opening reaction of thiiranes. Efficient synthesis of phenyl vinyl sulfides

A series of thiiranes react with benzyne to provide an efficient synthesis of phenyl vinyl sulfides. The reaction is stereospecific, thus producing cis-(phenylthio)-stilbene from cis-2,3-diphenylthiirane and trans-(phenylthio)stilbene from trans-2,3-diphenylthiirane.     

Dynamic coordination polymers with 4,4'-oxybis(benzoate): reversible transformations of nano- and nonporous coordination frameworks responding to present solvents

Reversible construction of a nanoporous framework from a nonporous framework has been found in the zinc(II) coordination polymer with 4,4'-oxybis(benzoate) (oba). [Zn(2)(oba)(2)(dmf)(2)].2DMF (1), which has 1 nm scale channels, transforms to the nonporous coordination polymer [Zn(oba)(H(2)O)] (2) with the loss of the open framework. Compound 2 on treatment with DMF reversibly yields nanoporous compound 1.     

Mass spectrometric studies on gibberellins

Based on the element maps of twenty-two gibberellin methyl esters fragmentations are discussed, which are characteristic of the common structural features as well as structural modification in gibberellin homologues.     

Separation selectivity of anionic metal complexes of N,N'-bis(hydroxybenzyl)ethylenediamine-N,N'-diacetic acid in ion and ion electrokinetic chromatography

The complexes of Fe(III), Co(III), Mn(III), Al(III), Cu(II), Ni(II), Cd(II) and Zn(II) with N,N'-bis(hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED) were separated by ion exchange in different modes: ion chromatography (IC) and ion electrokinetic chromatography (IEKC). In column IC these complexes were separated on an IonPac AS4a anion-exchange column (Dionex, USA). Parameters of the background electrolyte that were examined in IEKC mode include polymer, competing ion concentration and pH. The use of poly(diallyldimethylammonium chloride) (PDADMACl) as a modifier in IEKC provides separation selectivity only slightly different from that observed in IC on the IonPac AS4a column. Optimal separation conditions were found to be: 0.1 mM HBED, 50 mM PDADMAOH, 10 mM Na2 B4 O7, pH adjusted to 10 with acetic acid. The use of an aromatic ligand allowed a 10-fold decrease in detection limits of metal ions in comparison with previously studied EDTA. A separation efficiency up to 400,000 theoretical plates was demonstrated for IEKC.     

Compressed Corannulene in a Molecular Cage

Self‐assembled coordination cages can be employed as a molecular press, where the bowl‐shaped guest corannulene (C₂₀H₁₀) is significantly flattened upon inclusion within the hydrophobic cavity. This is demonstrated by the pairwise inclusion of corannulene with naphthalene diimide as well as by the dimer inclusion of bromocorannulene inside the box‐like host. The compressed corannulene structures are unambiguously revealed by single‐crystal X‐ray analysis.