A highly diastereoselective total synthesis of (±)-heritonin and (±)-heritol

A highly diastereoselective synthesis of heritol and heritonin by intramolecular cyclization on a preformed sensitive butenolide functionality is described.     

Electronic Structure and Magnetic Anisotropy of an Unsaturated Cyclopentadienyl Iron(I) Complex with 15 Valence Electrons

The 15 valence-electron iron(I) complex [Cp^ArFe(IiPr₂Me₂)] ( 1 , Cp^Ar=C₅(C₆H₄-4-Et)₅; IiPr₂Me₂=1,3-diisopropyl-4,5-dimethylimidazolin-2-ylidene) was synthesized in high yield from the Fe^II precursor [Cp^ArFe(μ-Br)]₂. ⁵⁷Fe Mössbauer and EPR spectroscopic data, magnetic measurements, and ab initio ligand-field calculations indicate an S= 3/2 ground state with a large negative zero-field splitting. As a consequence, 1 features magnetic anisotropy with an effective spin-reversal barrier of U_eff=64 cm⁻¹. Moreover, 1 catalyzes the dehydrogenation of N,N-dimethylamine–borane, affording tetramethyl-1,3-diaza-2,4-diboretane under mild conditions.     

Enhancing robustness of multiparty quantum correlations using weak measurement

Multipartite quantum correlations are important resources for the development of quantum information and computation protocols. However, the resourcefulness of multipartite quantum correlations in practical settings is limited by its fragility under decoherence due to environmental interactions. Though there exist protocols to protect bipartite entanglement under decoherence, the implementation of such protocols for multipartite quantum correlations has not been sufficiently explored. Here, we study the effect of local amplitude damping channel on the generalized Greenberger–Horne–Zeilinger state, and use a protocol of optimal reversal quantum weak measurement to protect the multipartite quantum correlations. We observe that the weak measurement reversal protocol enhances the robustness of multipartite quantum correlations. Further it increases the critical damping value that corresponds to entanglement sudden death. To emphasize the efficacy of the technique in protection of multipartite quantum correlation, we investigate two proximately related quantum communication tasks, namely, quantum teleportation in a one sender, many receivers setting and multiparty quantum information splitting, through a local amplitude damping channel. We observe an increase in the average fidelity of both the quantum communication tasks under the weak measurement reversal protocol. The method may prove beneficial, for combating external interactions, in other quantum information tasks using multipartite resources.     

Practical Synthesis of (±)‐Venlafaxine

A practical total synthesis of antidepressant (±)‐venlafaxine is disclosed.     

Synthesis and Cation Recognition Study of Novel Benzo Crown Ether Functionalized Enamine Derivatives

A novel series of benzo crown ether (dibenzo 18-crown-6 ether, benzo 18-crown-6 ether, and benzo 15-crown-5 ether) functionalized enamines derivatives from amino benzo crown ether (4-amino dibenzo 18-crown-6 ether, 4-amino benzo 18-crown-6 ether, 4-amino benzo 15-crown-5 ether) and substituted 3-(dimethylamino)-1-phenylprop-2-en-1-one compounds have been synthesized. All the synthesized compounds were characterized by infrared, ¹H NMR, ¹³C NMR, distortionless enhancement polarization transfer, and mass and elemental analysis techniques. The cation recognition property for benzo crown ether enamine 8a was studied by absorption and fluorescence spectroscopy.     

Short and Efficient Synthesis of Rubrolide E

Short and efficient synthesis of rubrolide E from commercially available 4‐methoxyacetophenone, employing ring‐closing metathesis, Knoevenagel condensation, and Reformatsky reactions, are the key steps are described.     

Rhenium–Germanium Triple Bonds: Syntheses and Reactions of the Germylidyne Complexes mer‐[X2(PMe3)3ReGe?R] (X=Cl,I, H; R=m‐terphenyl)

A general approach to the first compounds that contain rhenium–germanium triple and double bonds is reported. Heating [ReCl(PMe₃)₅] ( 1 ) with the arylgermanium(II) chloride GeCl(C₆H₃‐2,6‐Trip₂) ( 2 ; Trip=2,4,6‐triisopropylphenyl) results in the germylidyne complex mer‐[Cl₂(PMe₃)₃Re?Ge? C₆H₃‐2,6‐Trip₂] ( 4 ) upon PMe₃ elimination. An equilibrium that is dependent on the PMe₃ concentration exists between complexes 1 and 4 . Removal of the volatile PMe₃ shifts the equilibrium towards complex 4 , whereas treatment of 4 with an excess of PMe₃ gives a 1:1 mixture of 1 and the PMe₃ adduct of 2 , GeCl(C₆H₃‐2,6‐Trip₂)(PMe₃) ( 2 ‐PMe₃). Adduct 2 ‐PMe₃ can be selectively obtained by addition of PMe₃ to chlorogermylidene 2 . The NMR spectroscopic data for 2 ‐PMe₃ indicate an equilibrium between 2 ‐PMe₃ and its dissociation products, 2 and PMe₃, which is shifted far towards the adduct site at ambient temperature. NMR spectroscopic monitoring of the reaction of complex 1 with 2 and the reaction of complex 4 with PMe₃ revealed the formation of two key intermediates, which were identified to be the chlorogermylidene complexes cis/trans‐[Cl(PMe₃)₄Re?Ge(Cl)C₆H₃‐2,6‐Trip₂] (cis/trans‐ 3 ) by using NMR spectroscopy. Labile chlorogermylidene complexes cis/trans‐ 3 can be also generated from trans‐[Cl(PMe₃)₄Re?Ge? C₆H₃‐2,6‐Trip₂]BPh₄ ( 9 ) and (nBu₄N)Cl at low temperature, and decompose at ambient temperature to give a mixture of complexes 1 and 4 . Complex 4 reacts with LiI to give the diiodido derivative mer‐[I₂(PMe₃)₃Re?Ge? C₆H₃‐2,6‐Trip₂] ( 5 ), which undergoes a metathetical iodide/hydride exchange with Na(BEt₃H) to give the dihydrido germylidyne complex mer‐[H₂(PMe₃)₃Re?Ge? C₆H₃‐2,6‐Trip₂] ( 6 ). Carbonylation of 4 induces a chloride migration from rhenium to the germanium atom to afford the chlorogermylidene complex mer‐[Cl(CO)(PMe₃)₃Re?Ge(Cl)C₆H₃‐2,6‐Trip₂] ( 7 ). Similarly, MeNC converts complex 4 into the methylisocyanide analogue mer‐[Cl(MeNC)(PMe₃)₃Re?Ge(Cl)C₆H₃‐2,6‐Trip₂] ( 8 ). Chloride abstraction from 4 by NaBPh₄ in the presence of PMe₃ gives the cationic germylidyne complex trans‐[Cl(PMe₃)₄Re?Ge? C₆H₃‐2,6‐Trip₂]BPh₄ ( 9 ). Heating complex 4 with cis‐[Mo(PMe₃)₄(N₂)₂] induces a germylidyne ligand transfer from rhenium to molybdenum to afford the germylidyne complex trans‐[Cl(PMe₃)₄Mo?Ge? C₆H₃‐2,6‐Trip₂] ( 10 ). All new compounds were fully characterized and their molecular structures studied by X‐ray crystallography, which led to the first experimentally determined Re? Ge triple‐ and double‐bond lengths.