Three-component coupling of arynes, aminosilanes, and aldehydes

A three-component coupling of arynes, aminosilanes, and aldehydes enables diverse amino and hydroxymethyl groups to be incorporated directly into 1,2-positions of aromatic rings.     

Straightforward construction of diarylmethane skeletons via aryne insertion into carbon-carbon sigma-bonds

Two molar amounts of arynes were found to couple with nitriles via carbon-carbon sigma-bond cleavage, assembling diverse diarylmethane skeletons in a straightforward manner.     

The structures and electronic states of zinc-water clusters Zn(n)(H2O)(m) (n = 1-32 and m = 1-3)

Ab initio and Density Functional Theory (DFT) calculations have been carried out for zinc-water clusters Zn(n)-(H2O)(m) (n = 1-32 and m = 1-3, where n and m are the numbers of zinc atoms and water molecules, respectively) to elucidate the structure and electronic states of the clusters and the interaction of zinc cluster with water molecules. The binding energies of H2O to zinc clusters were small at n = 2-3 (2.3-4.2 kcal mol(-1)), whereas the energy increased significantly in n = 4 (9.0 kcal mol(-1)). Also, the binding nature of H2O was changed at n = 4. The cluster size dependency of the binding energy of H2O accorded well with that of the natural population of electrons in the 4p orbital of the zinc atom. In the larger clusters (n > 20), it was found that the zinc atoms in surface regions of the zinc cluster have a positive charge, whereas those in the interior region have a negative charge with the large electron population in the 4p orbital. The interaction of H2O with the zinc clusters were discussed on the basis of the theoretical results.     

Immunological Evaluation of Co-Assembling a Lipidated Peptide Antigen and Lipophilic Adjuvants: Self-Adjuvanting Anti-Breast-Cancer Vaccine Candidates

Co-assembling vaccines composed of a lipidated HER2-derived antigenic CH401 peptide and either a lipophilic adjuvant, Pam₃CSK₄, α-GalCer, or lipid A 506, were evaluated as breast cancer vaccine candidates. This vaccine design was aimed to inherit both antigen multivalency and antigen-specific immunostimulation properties, observed in reported self-adjuvanting vaccine candidates, by using self-assembly and adjuvant-conjugated antigens. Under vaccination concentrations, respective lipophilic adjuvants underwent co-assembly with lipidated CH401, which boosted the anti-CH401 IgG and IgM production. In particular, α-GalCer was responsible for the most significant immune activation. Therefore, the newly developed vaccine design enabled the optimization of adjuvants against the antigenic CH401 peptide in a simple preparatory manner. Overall, the co-assembling vaccine design opens the door for efficient and practical self-adjuvanting vaccine development.     

Dynamic path bifurcation in the Beckmann reaction: support from kinetic analyses

The reactions of oximes to amides, known as the Beckmann rearrangement, may undergo fragmentation to form carbocations + nitriles when the migrating groups have reasonable stability as cations. The reactions of oxime sulfonates of 1-substituted-phenyl-2-propanone derivatives (7-X) and related substrates (8-X, 9a-X) in aqueous CH(3)CN gave both rearrangement products (amides) and fragmentation products (alcohols), the ratio of which depends on the system; the reactions of 7-X gave amides predominantly, whereas 9a-X yielded alcohols as the major product. The logk-logk plots between the systems gave excellent linear correlations with slopes of near unity. The results support the occurrence of path bifurcation after the rate-determining TS of the Beckmann rearrangement/fragmentation reaction, which has previously been proposed on the basis of molecular dynamics simulations. It was concluded that path-bifurcation phenomenon could be more common than thought and that a reactivity-selectivity argument based on the traditional TS theory may not always be applicable even to a well-known textbook organic reaction.     

Three-component coupling using arynes and DMF: straightforward access to coumarins via ortho-quinone methides

ortho-Quinone methides, arising from a formal [2+2] cycloaddition between arynes and DMF, were found to facilely undergo a [4+2] cycloaddition with ester enolates or ketenimine anions to produce diverse coumarins in a straightforward manner.     

Modified Markó’s aerobic oxidation of alcohols under atmospheric pressure with air or molecular oxygen at room temperature

A modified version of Markó’s aerobic oxidation procedure, using highly pure (99.995+%) CuCl with 4,7-diphenyl-1,10-phenanthroline (dpPhen), DBAD, and Cs₂CO₃ (98% purity) successfully oxidized primary and secondary alcohols to the corresponding aldehydes and ketones in excellent yield at room temperature with either air or molecular oxygen under atmospheric pressure.     

Hetero-Diels-Alder reaction of photochemically generated α-hydroxy-o-quinodimethanes with trifluoromethyl ketones

Hetero-Diels-Alder reaction of α-hydroxy-o-quinodimethanes photochemically generated from o-tolualdehydes with trifluoromethyl ketones gave a mixture of hemiacetals and hydroxyaldehydes in fairly good yields. Their subsequent oxidation with PCC provided 1-isochromanones as formal oxidative [4+2] cycloaddition products. In contrast, similar reaction of aromatic ketones such as o-methylbenzophenone, 1-indanone, and α-tetralone gave exclusively the corresponding ketones having (trifluoromethyl)methylol groups at the o-position.     

Selective crystallization via vibrational strong coupling

The coupling of (photo)chemical processes to optical cavity vacuum fields is an emerging method for modulating molecular and material properties. Recent reports have shown that strong coupling of the vibrational modes of solvents to cavity vacuum fields can influence the chemical reaction kinetics of dissolved solutes. This suggests that vibrational strong coupling might also effect other important solution-based processes, such as crystallization from solution. Here we test this hitherto unexplored notion, investigating pseudopolymorphism in the crystallization from water of ZIF metal–organic frameworks inside optical microcavities. We find that ZIF-8 crystals are selectively obtained from solution inside optical microcavities, where the OH stretching vibration of water is strongly coupled to cavity vacuum fields, whereas mixtures of ZIF-8 and ZIF-L are obtained otherwise. Moreover, ZIF crystallization is accelerated by solvent vibrational strong coupling. This work suggests that cavity vacuum fields might become a tool for materials synthesis, biasing molecular self-assembly and driving macroscopic material outcomes.

Strong coupling of optical cavity vacuum fields and solvent vibrations leads to selective crystallization in a pseudo-polymorphic MOF system.