New N-nitrosoamines. 1. Synthesis and nitrosative cleavage of the Mannich bases derived from nitrogen-containing heterocycles and primary aliphatic amines

The reactions of isatin, benzotriazole, and succinimide with formaldehyde and methylamine yield monoamines RCH₂N(Me)CH₂R and methylenediamines RCH₂N(Me)CH₂N(Me)CH₂R. The use of ethylenediamine as the amino component affords N,N"-disubstituted imidazolidines, while the reactions with 3-aminopropan-1-ol give N-substituted tetrahydro-1,3-oxazines. RCH₂NBuⁱ ₂ was obtained from succinimide, formaldehyde, and diisobutylamine. Nitrosative cleavage of the amines obtained was studied; it was shown that monoamines and methylenediamines give N-nitrosoamines RCH₂N(NO)Me, which were structurally characterized by X-ray diffraction analysis. RCH₂NBuⁱ ₂ affords diisobutylnitrosamine, while imidazolidines transform into dinitroso compounds RCH₂N(NO)CH₂CH₂N(NO)CH₂R.     

曙红修饰电极对特丁基对苯二酚的灵敏检测

采用循环伏安法(CV)制备了曙红修饰玻碳电极(eosin Y/GCE),电化学交流阻抗法对修饰电极表面进行了表征,研究了特丁基对苯二酚(TBHQ)在该修饰电极上的电化学行为,建立了循环伏安法和差分脉冲伏安法(DPV)测定TBHQ的新方法。研究表明,修饰电极对TBHQ的氧化还原具有较好的电催化活性,在eosin Y/GCE上的氧化还原峰电位差从297 m V降至85 m V。在20~400 m V·s-1范围内,其氧化还原峰电流与扫速的平方根呈良好的线性关系,表明TBHQ在eosin Y/GCE上的电极反应受扩散控制。在0.10 mol·L-1磷酸盐缓冲溶液(p H 6.5)中,扫速为100 m V·s-1时,此修饰电极的DPV响应与TBHQ浓度在1~200μmol·L-1范围内呈线性关系,检出限(S/N=3)为0.1μmol·L-1。此修饰电极具有良好的选择性、重现性和稳定性,应用于油品中TBHQ的测定,回收率达95.0%~102.5%。该电极有望应用于多种食品中抗氧化剂的检测。     

New chiral bis(diphenylphospholane) ligands: design, synthesis, and application to catalytic enantioselective aldol reaction to ketones

New chiral bidentate diphenylphospholanes were designed targeting a catalytic enantioselective aldol reaction to ketones. Ligands 5l and 5m having cis-2-butenyl and cyclopropyl groups at the linker part, respectively, were identified as effective chiral ligands for a CuF-catalyzed enantioselective aldol reaction to ketones. Catalysts prepared from CuF·3PPh₃·2EtOH and these ligands produced ketone aldol products with up to 66% ee, which is promising particularly for this extremely difficult and important catalytic enantioselective carbon-carbon bond forming reaction. The enantioselectivity was strongly dependent on the linker structure. Construction of a deep chiral pocket around the copper metal with stable bidentate chelation is the key to meaningful enantioinduction.     

An Efficient Synthetic Method of 11,12-DihydroxylEudesmanolide Sesquiterpenoid from a-Santonin

11,12-dioxygenated eudesmanolide sesquiterpenoid is a large kind of naturally occuring sesquiterpenoids isolated from the medicinal plants, such as J. glutinosa1 and Flourensia heterolepsis 2. In constrast to much investigation of their isolation and structure characterization, the less about their synthesis have been reported. One of the reason may be the difficult hydroxylation at C-11. For example, the synthesis of a simple natural product, kudtriol3, required thirteen steps of reactions f…     

SIMS studies of polymeric tertiary structures in monolayers: Polysiloxane helical coil structures

A static SIMS study was performed using poly(dimethyl siloxane) (PDMS) as a model system to investigate the effects of tertiary structure on the ion formation mechanism and ion formation probability of fragments in the high mass region (>1000 Da). PDMS produced from anionic polymerization with a narrow polydispersity, can form well-ordered helically coiled monolayers using Langmuir-Blodgett methods at the air water interface, either in a hairpin configuration, if the endgroups are functional or as flat helically coiled chains. Reflection absorption Fourier transform infrared (RA-FTIR) spectroscopic analysis shows the changes in bonding between flat helically coiled PDMS and cast films from dilute solvents, which produces a random coil configuration. Differences between the model systems in infrared spectrum show evidence of changes in structure, producing variation in band formation. Also observed are changes in the band shape and relative peak area between the model systems. These polymeric changes translate into differences in the relative intensities of fragments formed in the repeating pattern of clusters in the high mass ToF-SIMS spectra of the ordered versus the random cast films. Both statistical chain break analysis and molecular mechanics simulations of structure are used to support the analysis.     

Extended Reaction Scope of Thiamine Diphosphate Dependent Cyclohexane‐1,2‐dione Hydrolase: From CC Bond Cleavage to CC Bond Ligation

ThDP‐dependent cyclohexane‐1,2‐dione hydrolase (CDH) catalyzes the C? C bond cleavage of cyclohexane‐1,2‐dione to 6‐oxohexanoate, and the asymmetric benzoin condensation between benzaldehyde and pyruvate. One of the two reactivities of CDH was selectively knocked down by mutation experiments. CDH‐H28A is much less able to catalyze the C? C bond formation, while the ability for C? C bond cleavage is still intact. The double variant CDH‐H28A/N484A shows the opposite behavior and catalyzes the addition of pyruvate to cyclohexane‐1,2‐dione, resulting in the formation of a tertiary alcohol. Several acyloins of tertiary alcohols are formed with 54–94 % enantiomeric excess. In addition to pyruvate, methyl pyruvate and butane‐2,3‐dione are alternative donor substrates for C? C bond formation. Thus, the very rare aldehyde–ketone cross‐benzoin reaction has been solved by design of an enzyme variant.     

The Synthesis of Tertiary Amides by theReaction of Adducts of Schiff Bases andAcyl Chlorides with Allylsamarium Bromide

Samariumdiiodideisanexcellentelectrontransferagent'-'.Theapplicationofsamariummetalinorganicsynthesishasstimulatedgreatinterestrecently'-'.CurranfirstreportedthesamariumGrignardreaction6.Allylmagnesiumbromideisusuallyaccompaniedwithagreatquantityof...     

UV-visible Absorption Studies of Tetrachloro-p-benzoquinone and Tertiary Amines Charge Transfer Complexes in Trichloromethane

TCBiswellknownasnacceptorwhichcanformCTcomplexeswithmanydonormolecules"',andalsocanbeusedintheanalysisandqualitycontrolofdrugsindifferentpharmaceuticaldosageforms3.AlthoughspectrophotometricalmethodisoftenusedtostudythecharacterofCTcomplexes,verylittleresearchonCTcomplexesformedbyTCBandsimpletertiaryaminehavebeenfound.Recently,weemploythespectrophotometricalmethodtoStudytheCTcomplexesusingtheTCBasnacceptorandtertiaryamineasdonors.Inthispaper,wereporttheaboveresultsandexplainsomephenomen…