Synthesis of N-alkyl substituted bioactive indolocarbazoles related to Gö6976

The syntheses of new nitrile and amide analogues of 7-keto Gö6976 are described. The amide analogue 22 was formed via the condensation with a new functionalized indoleacetic acid derivative 25 to overcome the solubility problem during the coupling reaction.     

An imino-Diels-Alder route to meso-2,6-disubstituted-4-piperidones

A convenient stereoselective preparation of meso-2,6-disubstituted-4-piperidones has been developed by imino-Diels-Alder reaction of 2-amino-1,3-butadienes with imines in the presence of catalytic amount of Cu(TfO)₂.     

Benzyl cleavage in the oxidation of cycleanine by mercuric acetate

The dehydrogenation of cycleanine with mercuric acetate in 10% AcOH (at the boil) has been studied. It has been shown that it is accompanied by oxidative cleavage similar to benzyl cleavage under the action of electron impact. The main reaction product (without complexone) is the 8-(4-hydroxymethylphenoxy)-6,7-dimethoxy-2-methylisoquinolinium salt C₁₉H₂₀NO₄Cl·1.5H₂O, mp 196°C. The oxidation of cycleanine in the presence of ethylenediaminetetraacetic acid gave the mercuride C₁₉H₁₉NO₃I₂Hg·2H₂O, mp 240°C (water).     

Benzyl cleavage in the oxidation of cycleanine by mercuric acetate

The dehydrogenation of cycleanine with mercuric acetate in 10% AcOH (at the boil) has been studied. It has been shown that it is accompanied by oxidative cleavage similar to benzyl cleavage under the action of electron impact. The main reaction product (without complexone) is the 8-(4-hydroxymethylphenoxy)-6,7-dimethoxy-2-methylisoquinolinium salt C₁₉H₂₀NO₄Cl·1.5H₂O, mp 196°C. The oxidation of cycleanine in the presence of ethylenediaminetetraacetic acid gave the mercuride C₁₉H₁₉NO₃I₂Hg·2H₂O, mp 240°C (water).All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 676–680, September–October, 1979.     

A new route to highly functionalized heterocyclic rings

A novel cascade reaction has been developed for the rapid construction of heterocyclic rings. The cyclization is thermally induced and does not involve the use of metal ions. This highly efficient construction of furans has been developed during studies directed toward the synthesis of the antibiotic lactonamycin 1.     

N-tert-Butylbenzenesulfenamide-catalyzed oxidation of alcohols to the corresponding carbonyl compounds with N-chlorosuccinimide

N-tert-Butylbenzenesulfenamide (1)-catalyzed oxidation of various primary and secondary alcohols to the corresponding aldehydes and ketones was efficiently carried out by using N-chlorosuccinimide (NCS) in the coexistence of potassium carbonate and molecular sieves 4 Å at easy-to-control temperatures ranging from 0°C to room temperature. The present catalytic oxidation was performed without giving any damage to the functional groups in alcohols, and was particularly effective in the oxidation of alcohols that formed labile aldehydes because of its mild reaction conditions. Further, selective oxidation of primary hydroxy groups took place in 1-catalyzed oxidation of several diols. Mechanistic investigation suggested that the chlorination of the sulfenamide 1 by NCS led to the formation of a key species, N-tert-butylbenzenesulfinimidoyl chloride (2), which in turn oxidized alcohols in the presence of potassium carbonate to afford carbonyl products by accompanying regeneration of the catalyst 1.     

Synthesis and insecticidal activity of new substituted N-aryl-N′-benzoylthiourea compounds

Eight new substituted N-aryl-N′-benzoylthioureas have been synthesised by a facile and mild method with high yield at room temperature. The structures of all compounds were confirmed by NMR, mass and high resolution mass spectroscopy. The preliminary bioassay tests show that two of the compounds (5b and 5e) exhibited a significant insecticidal activity on armyworm, Leucania separata Walker, at 500 mg l⁻¹.     

A new biocatalytic route to enantiopure N-carbamoyl amino acids by fast enzyme screening

The enantioselective enzymatic deamidation of (rac)-N-carbamoyl amino acid amides (Cbm-AA-NH₂) to enantiopure (L)-N-carbamoyl amino acids (Cbm-AA-OH) is described for the first time. Via fast screening methods of biocatalysts several proteases like Chirazyme P1, Chirazyme P2 and Subtilisin were identified, which give conversions of up to 47% and >98% ee. This conversion is most productive on aliphatic and primary amino acids.     

A new route to fullerene substituted phenylalanine derivatives

A series of fullerene substituted phenylalanine derivatives have been prepared by the condensation of 1,2-(4'-oxocyclohexano)fullerene with ester or Boc protected (4-amino)phenylalanine, H(2)NC(6)H(4)CH(2)CH(COR(1))(NHCOR(2))(where R(1) = OMe, R(2) = Me; R(1) = OH, R(2) = Me, O(t)Bu). Conversion of the imine to the corresponding amine is achieved by di-acid catalyzed hydroboration. Reaction of the N-Ac amino ester with BBr(3) led to the formation of the parent amino acid, while the Boc-protected derivative readily undergoes coupling with NH(2)-Gly-OEt. The reduction of the imine is not accompanied by hydroboration of the fullerene cage.     

A new asymmetric synthetic route to substituted piperidines

An asymmetric synthesis of substituted piperidines has been described. β-Cyclodextrin- or oxazaborolidine-catalyzed asymmetric reduction of α-azido aryl ketones to the corresponding alcohols has been employed as the key step along with ring closing metathesis and selective dihydroxylation.     

Chromium retention properties of N-alkyl quaternized poly(4-vinylpyridine)

The ability of solid N-alkyl quaternized poly(4-vinylpyridine) with hexyl, octyl and decyl bromide for the retention of chromate and dichromate forms of Cr(VI) in aqueous solutions is studied. The retention of Cr(VI) was investigated by batch equilibrium procedure and this study was supported by UV-vis spectrophotometry, infrared (IR) spectroscopy and thermal analysis (glass transition temperature and thermal degradation). The retention of Cr(VI) was possible in the range of concentrations between 1 × 10⁻⁶ and 1 × 10⁻³ mol/L and it was dependent on the length of the polyelectrolyte side aliphatic chain. Thermogravimetric analysis (TGA) indicated that solid phase, (N-alkyl quaternized poly(4-vinylpyridine), with Cr(VI) (P4VPyC8-Cr(VI)) is slightly more stable than P4VPyC8 in absence of Cr(VI). Differential scanning calorimetric (DSC) measurements indicate that the segmental movements are restricted due to the presence of chromate and/or dichromate ions in the solid phase.     

A convenient route to new Cyclopentadienyldinitrosyltungsten compounds

[C₅H₅W(NO)₂CO]PF₆ has been prepared and shown to be a useful precursor for a variety of new cationic and neutral tungsten nitrosyl compounds.     

A new method for the synthesis of n-alkyl-4-piperidones

Summary A new method, based on the reaction of the methiodides of N-methyl-4-piperidones with primary amines, was proposed for the synthesis of N-alkyl-substituted 4-piperidones.     

A new route towards N-(α-methoxybenzyl)aziridines

A new synthesis of N-(α-methoxyarylmethyl)-2,2-dimethylaziridines is presented. Different benzaldehydes were converted into the corresponding imines upon reaction with 2-bromo-2-methylpropylamine. Treatment of the latter imines with sodium methoxide afforded N-(α-methoxyarylmethyl)-2,2-dimethylaziridines in good yields.     

Synthesis and reactivity of unique heterocyclic structures en route to substituted diamines

Rhodium-catalyzed oxidative cyclization of allylic hydroxylamine-derived sulfamate esters furnishes a novel family of bicyclic aziridines that serve as functional precursors to substituted diamines. Investigations with the N4-Troc form of these heterocycles have led to manifold improvements in reaction performance and scope and have revealed unique differences in the stability and reactivity of such compounds dictated by the choice of N4-protecting group.     

A new synthetic route to substituted 1-fluoro-1-cyclopropanecarboxylates

Substituted 6-fluoro-2,4-dioxo-3-azabicyclo[3.1.0]hexane-6-carboxylates were obtained as a mixture of the exo- and endo-isomers by reaction of substituted 6,8-dioxo-2,3,7-triazabicyclo[3.3.0]oct-3-en-4-carboxylates with N-fluoropyridinium tetrafluoroborate.     

A general route to unsubstituted N-aryl and heteroarylaminobenzenesulfonamides

Starting from suitably protected 3- and 4-aminobenzenesulfonamides, a practical two-step strategy for the synthesis of unsubstituted N-aryl and heteroarylaminobenzenesulfonamides was devised. Strong bases are tolerated during the N-arylation step. Overall moderate to excellent yields are reported.     

A new route to vinyltributyltin compounds by flash pyrolysis of alkyltributyltin acetates

Flash pyrolysis of alkyltributyltin acetates, at high temperatures (600–850° C) under a moderate vacuum provides a convenient route to vinyltin derivatives.