Radical Reductive Alkylation of Enamines: Conversion of the Products into Alkenes and Primary Amines

Procedures for the conversion of tertiary amines, obtained by radical reductive alkylation of enamines, into alkenes (Cope reaction) and primary amines (double β-elimination reaction) are presented.     

Conversion of alcohols into alkyl bromides and iodides via O-alkylisoureas

Treatment of O-alkylisoureas with trifluoromethanesulphonic acid and a tetrabutylammonium salt (bromide or iodide) affords alkyl halides in high yields.     

Conversion of alcohols into N-alkyl anilines via an indirect aza-Wittig reaction

Iridium catalysed oxidation of alcohols provides the aldehydes required for in situ aza-Wittig reactions and the so-formed imines are reduced to amines under the reaction conditions.     

A Facile Conversion of Tertiary Amines into [2-(dialkylamino)vinyl]triphenylphosphonium salts

Halogenation of Et₃N, (i-Pr)₂EtN, and N-ethylmorpholine or of enamines with dichlorotriphenylphosphorane gives in up to 75% yield the corresponding [2-(dialkylamino)vinyl]triphenylphosphonium chlorides, which can be readily converted into the corresponding stable crystalline tetraphenylborates (Schemes 2 and 3).     

Conversion of chiral unsaturated cyanohydrins into chiral carba- and heterocycles via ring-closing metathesis

Aliphatic unsaturated cyanohydrins 1-3 served as starting materials in the synthesis of a set of new chiral unsaturated cyclic 1,2-ethanolamines. Combining a Grignard addition-NaBH₄ reduction sequence with a ring-closing metathesis afforded unsaturated cyclic 1,2-ethanolamines 7-11 and 22-25 in good yields and high ee (96-99%). The conversion of cyanohydrins 1-3 via a DIBAL reduction-transimination-NaBH₄ reduction sequence, using allylamine, followed by ring-closing metathesis yielded tetrahydropyridines 28, tetrahydroazepinols 33 and tetrahydroazocinols 34 in high yields and excellent ee (97-99%).     

Selective N-Monomethylation of Primary Amines via N-Trialkylsilyl-Lithioamines

Transformation of a primary amine to a secondary amine can be achieved by reaction with an alkyl halide in the presence of an excess of the primary amine to suppress multiple alkylation, but, in general, direct alkylation is not the preferred method when the product alkylated amine is more nucleophilic than the startirg amine. More efficient procedures involve a relative vitiation of the nucleophilicity of the monoalkylated product with respect to that of the unalkylated substrate. Such an effect may be realised by the incorporation of monovalent activating groups (Z), which increase the acidity of the amido-proton and allow alkylation of a stabilised amidoanion, often generated in situ, this species being more reactive than a simple amine. Since in the conversion of a primary to a secondary amine only one amido-proton remains after incorporation of the activating group, further N-alkylation is obviated (Scheme 1.)     

Copper‐Promoted Conversion of Aromatic Amines into Trifluoromethylated Arenes: One‐Pot Sandmeyer Trifluoromethylation

A simple copper‐promoted one‐pot Sandmeyer trifluoromethylation of aromatic amines with Langlois’ reagent has been demonstrated. The reaction is performed in mild reaction conditions under an air atmosphere with good substrate scope and functional group compatibility. It provides an alternative and straightforward synthetic approach to access a variety of trifluoromethylated arenes.     

A Convenient Method for the Conversion of Amines to Carbamates

Treatment of primary or secondary amines with bis(trimethylsilyl)acetamide followed by addition of methyl, vinyl, or 2,2,2-trichloroethyl chloroformate provides a convenient method for the preparation of the corresponding carbamates.     

S,N-Compounds via Amines and Sulphur Halides

Abstract

The many products got by reactions of amines with sulfur halides are discussed. Special attention is given to the intermediate thionitroso compounds, the N-thiosulfinylamines and the persistent radicals 1,2,3-dithiazolyles. New results about the course of the HERZ reaction are described.     

Substrate-Independent Stable and Adherent Reactive Surface Coatings and their Conversion with Amines

Summary: To create stable, adherent and reactive surface coatings, a hybrid polymer composed of poly(methylsilsesquioxane) (PMSSQ) and poly(pentafluorophenyl acrylate) PFPA with a M_n of 32000 g/mol was prepared by a RAFT polymerization procedure. These hybrid polymer has been used for coating experiments. The PFPA part enabled a variable functionalization of the coating afterwards. The stability on various substrates (e.g. glass, PMMA, steel) was tested in an ISO tape test. These reactive surface coatings were modified using different amines, such as amino-terminated PEG, dodecyl amine and N-isopropyl amine. The conversion was analyzed by FT-IR and contact angle measurements.     

Catalysis Conversion Methane into C2 Hydrocarbons via Electric Field Enhanced Plasma

In this paper the effect of catalyst and carrier in electric field enhanced plasma on methane conversion into C2 hydrocarbons was investigated. Methane coupling reaction was studied in the system of continuous flow reactor on Ni, MoO3, MnO2 catalysts and different ZSM-5 carriers. The per pass conversion of methane can be as high as 22%, the selectivity of ethylene can be as high as 23.8%, of acetylene 60.8%, of ethane 5.4% and of total C2 hydrocarbons was more than 90%. ZSM-5-25 was the better carrier and MnO2 was the better active component. The efficiency of energy was as high as 7.81%.     

常压连续反应性萃取法由预处理生物质制备乙酰丙酸

采用双相联系流反应性萃取技术实现常压下小麦秸秆向乙酰丙酸的转化,其中生物质在水相中完成降解,形成乙酰丙酸,而后比水密度大的有机相作为乙酰丙酸的萃取相,把生成的乙酰丙酸萃取到有机相,并经过虹吸到收集瓶中,有机相经蒸馏可反复使用,实现了预处理生物质到乙酰丙酸的高效转化,乙酰丙酸最大的产率为30.66%.     

Stereoselective Thermal Conversion of s-trans-Diallene into Dimethylenecyclobutene via s-cis-Diallene in the Crystalline State

A conrotatory [2+2] cyclization is the second step in the solid-state thermal reaction of s-trans-tetraaryldibromohexatetraenes 1 to cyclobutenes 4 . Prior to the cyclization 1 rearranges into the cis conformer 3 . Surprisingly the thermal rearrangement and the stereoselective cyclization occur readily in spite of the required motion of the sterically bulky substituents. R=Ph, p-MeC₆H₄.     

Conversion of norbornene derivatives into vicinal-dithioethers via S8 activation

Norbornene reacts with elemental sulfur to give a mixture of trithiolane and pentathiepane. Sulfuration of norbornene derivatives was achieved with elemental sulfur, by using a catalytic amount of a nickel complex, to afford selectively the corresponding trithiolanes. The most effective catalytic system was Ni(NH₃)₆Cl₂ in dimethylformamide. The trithiolanes were reduced with super-hydride into 1,2-dithiolate salts, and quenched in situ to form vicinal-dithioethers.     

A New Novel and Practical One Pot Methodology for Conversion of Alcohols to Amines

A convenient and efficient one pot sequence has been developed for the transformation of alcohols to amines using Sodium azide, triphenylphosphine in CC1₄-DMF.     

Conversion of solid amorphous zirconium and hafnium phosphates into alpha crystalline form via molten oxalic acid

Solid amorphous zirconium phosphate /ZPa/ and hafnium phosphate /HPa/ are mixed with an excess of solid oxalic acid dihydrate and are digested in molten oxalic acid. Then oxalic acid is removed by extraction or by heating. The residue is washed with dilute HCl /0.01M/ and redistilled water. By this method -ZP and -HP is formed from amorphous ones.