On the reaction of Ph2PNHPPh2 with RNCS (R=Et, Ph, p-NO2C6H4): preparation of the zwitterionic ligand EtNHC(S)Ph2P==NPPh2C(S)NEt (HSNS) and the zwitterionic metalate [(SNS)Rh(CO)

The reaction of Ph(2)PNHPPh(2) (PNP) with RNCS (Et, Ph, p-NO(2)(C(6)H(4))) gives addition products resulting from the attack of the P atoms of PNP on the electrophilic carbon atom of the isothiocyanate. When PNP is reacted with EtNCS in a 1:2 molar ratio, the zwitterionic molecule EtNHC(S)PPh(2)==NP(+)Ph(2)C(S)N(-)Et (HSNS) is obtained in high yield. HSNS can be protonated (H(2)SNS(+)) or deprotonated (SNS(-)), behaving in the latter form as an S,N,S-donor pincer ligand. The reaction of HSNS with [(acac)Rh(CO)(2)] (acac=acetylacetonate) affords the zwitterionic metalate [(SNS)Rh(CO)]. Other products can be obtained depending on the R group, the PNP/RNCS ratio (1:1 or 1:2), and the reaction temperature. The proposed product of the primary attack of PNP on RNCS, Ph(2)PN==PPh(2)C(S)NHR (A), cannot be isolated. Reaction of A with another RNCS molecule leads to 1:2 addition compounds of the general formula RNHC(S)PPh(2)==NP(+)Ph(2)C(S)N(-)R (1), which can rearrange into the non-zwitterionic product RNHC(S)PPh(2)==NP(S)Ph(2) (2) by eliminating a molecule of RNC. Two molecules of A can react together, yielding 1:1 PNP/RNCS zwitterionic products of the formula RNHCH[PPh(2)==NP(S)Ph(2)]PPh(2)==NP(+)Ph(2)C(S)N(-)R (3). Compound 3 can then rearrange into RNHCH[PPh(2)==NP(S)Ph(2)](2) (4) by losing a RNC molecule. When R=Et (a), compounds 1 a, 2 a (HSNS), and 4 a have been isolated and characterized. When R=Ph (b), compounds 2 b and 4 b can be prepared in high yield. When R=p-NO(2)C(6)H(4) (c), only compound 3 c is observed and isolated in high yield. The crystal structures of HSNS, [(SNS)Rh(CO)], and of the most representative products have been determined by X-ray diffraction methods.     

Radical amination with sulfonyl azides: a powerful method for the formation of C-N bonds

A novel reaction for the introduction of an azide moiety by means of a mild radical process is currently under development. Sulfonyl azides are suitable azidating agents for nucleophilic radicals, such as secondary and tertiary alkyl radicals. More electrophilic radicals, such as enolate radicals, do not react with sulfonyl azides. This feature allowed the development of efficient intra- and intermolecular carboazidations of olefins. Due to the versatility of the azido group, this reaction has an important synthetic potential, as already demonstrated by the preparation of the core of several alkaloids, particularly those containing an amino-substituted quaternary carbon center, such as FR901483.     

Carbon Dioxide as an Alternative C1 Synthetic Unit: Activation by Transition-Metal Complexes

The carbon dioxide molecule has been of limited importance as a synthetic unit in organic chemistry. When it is coordinated to transition metals, however, completely new possibilities arise; CO₂ can bond to metal complexes in a variety of ways and can enter into insertion and coupling reactions, or become catalytically attached to other substrates. The formation of C? C bonds between carbon dioxide and unsaturated hydrocarbons under conditions of homogeneous catalysis makes available new synthetic routes to industrially interesting organic compounds.     

Synthesis of Functionalized o‐, m‐, and p‐Terphenyl Derivatives by Consecutive Cross‐Coupling Reactions of Triazene‐Substituted Arylboronic Esters

Triazene‐substituted arylboronic esters were prepared readily from the corresponding aryl magnesium derivatives and shown to function as a new class of donor–acceptor‐substituted coupling reagents. The selective functionalization of these aromatic derivatives led to a wide variety of terphenyl derivatives in which the original bifunctional unit (often further substituted with another functional group) formed the central aromatic ring. The functionalized terphenyl derivatives were formed in two efficient cross‐coupling steps from the triazene‐substituted boronic esters: Suzuki cross‐coupling with an aryl halide was followed by BF₃?OEt₂‐induced palladium‐catalyzed coupling of the diazonium salt generated in situ from the triazene with an arylboronic acid.     

稀土含硫有机配体配合物的合成与应用研究进展

简要综述了稀土含硫有机配体配合物的常用合成方法, 概述了该类型配合物在橡胶硫化、摩擦学、稀土农用和医药等领域的潜在应用, 并指出了稀土含硫配合物今后的研究重点.     

One-step analysis of testis steroidogenesis from neonatal exposure to synthetic estrogen by normal-phase HPLC

Neonatal exposure to synthetic estrogen endocrine disruptors or estrogen-receptor inhibitors induces developmental abnormalities in the male reproductive system. To investigate whether neonatal exposure affects spermatogenesis in juvenile and pubertal testis, Sprague-Dawley rat pups were given synthetic estrogen endocrine disruptors or estrogen-receptor inhibitors by a single injection on the day of birth at concentrations ranging between 2 to 40 mm, and sacrificed on day 21 (juvenile), 35 (prepuberty) or 50 (puberty). The testes were weighed and examined histologically at each stage. Further, the metabolites of steroidogenesis were analyzed using normal-phase high performance liquid chromatography. Neonatal exposure significantly reduced testis weights and steroidogenesis to one- fifth to one-half of that of the juvenile control, and further suppressed irreversible steroidogenesis and spermatogenesis during puberty.     

The tert-butyl-NNO-azoxy group in the synthesis of 1,2,4-benzotriazin-3(4H)-one 1-oxides

Treatment of 2-(tert-butyl-NNO-azoxy)anilines with phosgene at 20 °C was proposed as a novel route to 1,2,4-benzotriazin-3(4H )-one 1-oxides. This method involves a new reaction, viz., an intramolecular interaction of the tert-butyl-NNO-azoxy group with a C-electrophile (leading to the formation of the N(2)—C(3) bond of the triazine ring) followed by elimination of the tert-butyl group. Complete assignment of the signals in the ¹H and ¹³C NMR spectra of the compounds obtained was performed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1507–1509, August, 2007.     

Thermal degradation of cereal straws in air and nitrogen

Multigram quantities (2.5-10 g) of highly purified IgG were obtained within 4 h from serum by using Avid AL packed in a radial-flow column. Avid AL is an affinity gel containing a synthetic, low-mol-wt ligand capable of selectively binding IgG from serum of all animal species tested. By packing the gel in a radial-flow column up to 500 mL, a high flow rate of 50 mL/min can be achieved without adversely affecting the performance of the gel and the purity of the isolated antibody.