New one-pot procedure for the synthesis of diprotected amino alcohols from unprotected vinyl aziridines

An unprecedented one-pot reaction that allows the synthesis of diprotected amino alcohols from unprotected vinyl aziridines is reported. The results demonstrate the possibility to use various acyl chlorides in order to obtain differently functionalised fragments. Mechanistic insights are given.     

An additional structural and electrical study of polymeric haloplumbates(II) with heterocyclic diprotonated amines

The crystal structures of three polymeric bidimensional piperazinium, N,N'-dimethylpiperazinium, and N-benzylpiperazinium hydrate haloplumbates(II) and one polymeric monodimensional N,N'-dimethylpiperazinium hydrate haloplumbate(II) were determined by means of X-ray analysis. The (pipzH2)[PbCl4] salt is monoclinic, space group P2(1)/c, with a = 5.778(2) A, b = 22.612(26) A, c = 9.061(4) A, beta = 95.37(6) degrees, Z = 4; (me2pipzH2)[PbBr4] crystallizes in the monoclinic P2(1) space group with a = 6.101(3) A, b = 18.822(12) A, c = 6.229(2) A, beta = 98.62(4) degrees, Z = 2; the crystals of (me2pipzH2)2[Pb3I10].4H2O are monoclinic, space group P2(1)/c, a = 19.054(4) A, b = 12.239(3) A, c = 18.273(4) A, beta = 93.42(12) degrees, Z = 4; (benzpipzH2)3[Pb2Br10].2H2O crystallizes in the monoclinic P2(1)/c space group with a = 22.380(22) A, b = 9.304(15) A, c = 24.577(25) A, beta = 94.28(11) degrees, Z = 2. Different model type structures, such as one-dimensional linear chain, ribbonlike, and perovskite-like, were observed, and factors governing these structural arrangements are pointed out. The compounds were also investigated by means of thermal and electrical measurements, and correlations between electrical properties and crystal structures were noted.     

Nonlinear approach to electrodynamics

A nonlinear approach to electrodynamics is reviewed. On imposing a nonlinear constraintA A = – ², together with the usual gauge-invariant electromagnetic field Lagrangian, it is found that the resulting equations of motion have, besides the photon, a static spherically symmetric extended solution which may be regarded as a charged particle. A magnetic dipole moment (spin) can also arise as a solution of the equations of motion if, as expected, it is treated as a first-order quantum effect. In the limit for small quantum fields and pointlike charged particles, the quantum mechanical equivalence of the approach with the usual Lagrangian formulation of the electromagnetic interaction of a charged scalar field is heuristically shown. Moreover the possibility of constructing charged fermion fields from the solution having both a charge and a magnetic moment is illustrated. In such an approach the photon is associated with the spontaneous breaking of Lorentz symmetry, and the emission of soft photons does not exhibit any infrared divergences.     

A highly regioselective azidolysis of 2,3-epoxy amines: an unexpected [Ti(O-i-Pr)2(N3)2] mediated C-2 opening

The Lewis acid-catalysed regioselective azidolysis of 2,3-epoxy amines has been investigated. The results obtained demonstrated that using TMSN₃ as a source of azide, the appropriate choice of Lewis acid allowed to direct the regiochemistry of the ring opening. The present methodologies provide a powerful tool in organic synthesis for the preparation of diaminoalcohol moieties.     

Novel Stereocontrolled Preparation of Amino Polyols from 2,3-Aziridine Alcohols

Starting from 2,3-aziridine alcohols, a novel and versatile preparation of optically active amino polyol was achieved using a simple strategy with few purification steps and a good overall yield.     

Steric distortion of planar NiP<Subscript>2</Subscript>N<Subscript>2</Subscript> chromophores: a spectral,cyclic voltammetric and single crystal X-ray structural study

The complexes trans-[Ni(4-MP)₂(NCS)₂]·MeCN (1) and trans-[Ni(3-MP)₂(NCS)₂] (2) (4-MP = tri(4-methylphenyl)phosphine, 3-MP = tri(3-methylphenyl)phosphine) were prepared and characterized by IR, UV–visible, NMR spectra, CV, TGA and single crystal X-ray crystallography. Both the complexes have planar geometry and are diamagnetic. The Ni–P distances in both complexes are relatively short as a result of strong back donation from nickel to phosphorus. The phenyl rings in the 3-MP analogue (2) show increased pitching with reference to the plane formed by the ipso carbons due to increased steric effects. For complex (2), the N–Ni–N and P–Ni–P angles are significantly lower than the almost linear N–Ni–N and N–Ni–P angles observed for both complex (1) and trans-[Ni(PPh₃)₂(NCS)₂]. This observation indicates that the 3-methylphosphine ligand forces complex (2) to distort towards a tetrahedral geometry. IR spectra of both complexes show strong bands around 2,090 cm⁻¹ due to N-coordinated thiocyanate, while the electronic spectra contain d–d transitions around 452 nm. Cyclic voltammograms show that the irreversible one-electron reduction potentials increase in the following order: trans- [Ni(PPh₃)₂(NCS)₂] < trans- [Ni(3-MP)₂(NCS)₂] < trans-[Ni(4-MP)₂(NCS)₂], revealing the electron releasing effect of the methyl groups. The planar complexes exhibit interallogony in coordinating solvents.