Oxime radical promoted dioxygenation, oxyamination, and diamination of alkenes: synthesis of isoxazolines and cyclic nitrones

Up the tempo: The intramolecular addition of oxime radicals to C?C bonds was achieved by using DEAD and TEMPO to give 4,5-dihydroisoxazoles as a result of a C?O bond-forming, 5-exo-trig cyclization. γ,δ-Unsaturated ketoximes also reacted to afford cyclic nitrones through C?N bond formation. The reactions offer a metal-free approach for the vicinal difunctionalization of unactivated alkenes.     

Expeditious Synthesis of Enantiopure,Orthogonally Protected Bis‐α‐Amino Acids (OPBAAs) and their Use in a Study of Nod1 Stimulation

A convenient approach towards the synthesis of orthogonally protected chiral bis‐α‐amino acids (OPBAAs) is described. The key transformations include: (1) a highly stereoselective conjugation (alkylation) of the Schöllkopf bis‐lactim ethers and oxazolidinyl alkyl halides to build a backbone skeleton; and (2) our orthogonal protection strategy. A series of enantiopure OPBAAs bearing a variety of alkyl chain as a spacer; two stereogenic centers; and three protecting groups were prepared as examples. These versatile molecules were applied to the synthesis of biologically interesting di‐ or tri‐peptide analogues, including chiral iE‐meso‐DAP and A‐iE‐meso‐DAP, for the study of Nod1 activation in the innate immune response.     

Bi(NO3)3 · 5H2O mediated synthesis of 4,4′-diaminotriarylmethane leuco malachite compounds under solvent-free conditions

In this report, we described the synthesis and characterization of a variety of diaminotriarylmethane derivatives with dimethylamino functional groups. These compounds were synthesized by the tandem regio-selective electrophilic aromatic substitution reaction of N,N-dimethylaniline with aryl aldehydes to form the corresponding diaminotriarylmethane compounds. In our strategy, Bi(NO₃)₃ was used as a catalyst under solvent free conditions to afford the desired products in good to excellent yields.      

Synthesis of Giant Zeolite Crystals by a Bulk-Material Dissolution Technique

Using a quartz glass tube as a bulk silica source under aqueous hydrothermal conditions afforded giant crystals of MFI zeolite about 3 mm in size (see photo). Similar procedures were successfully applied to bulk aluminosilicate ceramics to synthesize large crystals of other zeolites, such as ANA, JBW, CAN, and SOD.     

P9]+ [Al(OR(F))4)]-, the salt of a homopolyatomic phosphorus cation

Positive at last: The first condensed-phase homopolyatomic phosphorus cation [P(9)](+) was prepared using a combination of the oxidant [NO](+) and weakly coordinating anion, [Al{OC(CF(3))(3)}(4)](-). [P(9)](+) consists of two P(5) cages linked by a phosphonium atom to give a D(2d)-symmetric Zintl cluster. NMR (see picture), Raman, and IR spectroscopy, mass spectrometry, and quantum-chemical calculations confirmed the structure.     

The diaryl(oxy)methyl group: more than an innocent bystander in chiral auxiliaries, catalysts, and dopants

Either as the free alcohol or deprotonated, a carbinol residue bearing gemial, identical aryl residues can at first sight be recognized as an achiral structural unit. When incorporated, however, into a chiral molecule, the two aryl groups become diastereotopic. Thus, they might contribute to an enhancement in stereoselectivity and do so in a variety of reactions. This Minireview highlights developments in stereochemistry when the diaryl(oxy)methyl group is involved, with emphasis given to the beneficial effect of this moiety. Of particular focus are auxiliaries, the stoichiometric use of metal complexes, metal and organocatalysts, and finally chiral dopants for liquid crystals, all featuring the diaryl(oxy)methyl group.