Synthesis of Spiropyrimidodiazepines and Spirodiazepinopurines by Tandem Nitroso‐ene/Diels–Alder Reactions

New spirocyclic heterocycles 8, 16, 19/20, 25, 27 , and 30 derived from pyrimido[4,5‐b][1,4]diazepin]‐8′(9′H)‐one were synthesised by a tandem nitroso‐ene/Diels–Alder reaction of 4‐(alkenoylamino)‐5‐nitrosopyrimides. The crystal structure of 16 was established by X‐ray analysis. It is characterised by four pairs of intermolecular H‐bonds linking every two molecules in the unit cell. Sequential imine reduction and intramolecular condensation of the C(4′)‐(acylamino)‐pyrimido[4,5‐b][1,4]diazepines 27 and 30 led to the [1,4]diazepino[1,2,3‐gh]purines 28 / 29 and 31 , respectively.     

用亚硝基R盐螯合树脂分离富集催化极谱法测定矿石中的铱

本文研究了利用亚硝基Ｒ盐螯合形成的树脂，分离富集试液中痕量贵金属元素铱的实验条件。并利用ＪＰ－１型示波极谱仪，在１．５０ｍｏｌ／Ｌ盐酸＋５．０×１０＾－５ｍｏｌ／Ｌ硫脲＋０．２ｍｏｌ／Ｌ盐酸＋５．０×１０＾－５ｍｏｌ／Ｌ硫脲＋０．２ｍｏｌ／Ｌ碘化钾＋碲（ρ（Ｂ）＝０．４ｍｇ／Ｌ）的混合底液中，对铱进行极谱催化波测定。在示波极谱仪上峰电位约－０．５５Ｖ（银汞齐为参比电极），可测定试液中５．０×１．０     

Denitrosation of N-Nitrososulfonamide as Chemical Probe for Determination of Binding Constants to Cyclodextrins

The influence of β-CD concentration on the acid hydrolysis of N-methyl-N-nitroso-p-toluenesulfonamide (MNTS) has been studied in the presence and absence of different alcohol concentrations. The rate of the denitrosation reaction in bulk water decrease as the β-CD concentration increases due to MNTS complexation in the CD cavity and the reaction taking place exclusively outside the cyclodextrin. Changes in this inhibition due to the presence of β-CD allow us to obtain the binding constants of different alcohols to the cyclodextrin. These binding constants are in very good agreement with those determined in the bibliography by other methods.     

2-Substituted nitrones and isomeric hydroxylamines - obtained via aluminium amalgam reduction of nitro nitriles and ketones—a new access to convenient intermediates for nitroso carbonyl compounds preparation

Substituted five-membered cyclic nitrones (pyrroline N-oxides) have been obtained in good to high yields from tertiary γ-nitro ketones and nitriles employing aluminium amalgam as a reducing agent in moist diethyl ether or THF. Attempts to obtain cyclic amino nitrones from α- or β-nitro nitriles failed and only the corresponding hydroxylamines have been isolated. Both nitrones and hydroxylamines have been used for synthesis of tertiary C-nitroso nitriles or ketones.     

The ‘t‐Amino Effect’ of ortho‐Nitroso Amines. Synthesis of 2,6‐Diaminoadenine Derivatives from 6‐(Dialkylamino)‐5‐nitrosopyrimidines

The ‘t‐amino effect’ of amino‐nitroso compounds was documented by preparing the (dialkylamino)‐nitroso pyrimidines 4 – 18 , and cyclising them under thermal conditions in high yields to the purine derivatives 19 – 32 . The reactivity of the amino‐nitroso‐pyrimidines, particularly of 17 derived from diethyl iminodiacetate, and of 19 , derived from 1‐phenylimidazolidine, correlates with the stability of the intermediate azomethine ylide. Thermolysis of the amino‐nitroso‐pyrimidines 34 – 37 , possessing dialkylamino substituents at C(4) and C(6), proceeded by protiodenitrosation, leading to 38 – 41 .     

Novel organic catalysts for the direct enantioselective α-oxidation of carbonyl compounds

The proline-derived N-sulfonylcarboxamide-catalyzed direct enantioselective α-oxidation of ketones and aldehydes with nitrosobenzene is presented. The reactions proceed smoothly furnishing the corresponding α-aminoxylated compounds in good yields with up to >99% ee. The proline-derived N-sulfonylcarboxamides were also found to be excellent catalysts for the direct enantioselective nitroso Diels-Alder-type reaction between nitrosobenzene and α,β-unsaturated cyclic ketones yielding the corresponding bicyclic Diels-Alder adduct products with up to >99% ee. The proline-derived N-sulfonylcarboxamides represent a readily available and highly modular novel type of organic catalyst.     

Detection of N-nitroso-bile acids at 285 nm in reverse-phase HPLC

In the present study, we developed a novel, simple, and specific detection method using an RP-HPLC at UV 285 nm for the separation and quantification of N-nitroso-bile acids. First, we found that N-nitroso-bile acids have a specific spectrophotometric absorbance at 285 nm. Using this 285 nm detection system, we could especially measure N-nitroso-bile acids, even in co-existence of non-N-nitroso-bile acids. Next, we observed the decomposition of N-nitroso-glychocholate under alkaline, acidic, and neutral conditions. N-nitroso-glychocholate rapidly decomposed under alkaline conditions (pH 9) (t(1/2) = 0.96 h), but remained fairly stable under acidic (pH 2) (t(1/2) = 12.8 h) and neutral (pH 7) (t(1/2) = 7.8 h) conditions. This study is the first report, which simply and specifically analyzes N-nitroso-bile acids using an RP-HPLC system.     

亚硝基R盐离子对固相萃取光度法测定钴(Ⅱ)

研究了用亚硝基R盐离子对固相萃取光度法测定钴,在pH 6.0的HOAc-NH4OAc缓冲介质中,溴化十六烷基三甲基铵(CTMAB)存在下,亚硝基R盐与钴反应生成3∶1稳定络合物,该络合物可用C18固相萃取小柱富集,富集倍数达100倍,小柱上富集的络合物用乙醇洗脱后用光度法测定,钴的质量浓度在0.05~5.0 mg.L-1内符合比耳定律。方法用于食品样和水样中钴的分析,结果与AAS法测得结果一致,RSD值(n=5)≤2.5%,回收率在97%~103%之间。     

Selective reduction of alkenes, α,β-unsaturated carbonyl compounds, nitroarenes, nitroso compounds, N,N-hydrogenolysis of azo and hydrazo functions as well as simultaneous hydrodehalogenation and reduction of substituted aryl halides over PdMCM-41 catalyst under transfer hydrogen conditions

Chemoselective reductions of alkenes, α,β-unsaturated carbonyl compounds, nitro and nitroso compounds, N,N-hydrogenolysis of azo and hydrazo functions as well as simultaneous reduction and hydrodehalogenation of substituted aryl halides, including bulkier substrates, were achieved by catalytic transfer hydrogenation (CTH) using mesoporous PdMCM-41 catalyst. The yields were practically unaffected upon recycling of the catalyst. Further, the CTH process is accomplished without affecting the reduction of any other reducible functional group.     

A Novel Synthetic Route to Furan-Lignans

Three naturally occurring furan–lignans and two analogs have been synthesized by a short and efficient route starting from the corresponding aryl acid. The selective reductive removal of allylic hydroxy by palladium oxide in a mixed solvent of THF–CHCl₃ was employed as the key step.