Search results for "Alkylation"

3,4-Dihydro-2H-pyrrole-2-carbonitriles: Useful Intermediates in the Synthesis of Fused Pyrroles and 2,2′-Bipyrroles

2016

Various heterocyclic structures containing the pyrrole moiety have been synthesized from easily accessible 3,4-dihydro-2H-pyrrole-2-carbonitriles in one-pot procedures. 5,6,7,8-Tetrahydroindolizines, 2,3-dihydro-1H-pyrrolizines as well as 6,7,8,9-tetrahydro-5H-pyrrolo[1,2-a]azepines were obtained from these precursors in high yields in an alkylation/annulation sequence. The same conditions were applied in the synthesis of a 5,8-dihydroindolizine, which could easily be transformed to the corresponding indolizine by dehydrogenation. Furthermore, oxidative couplings of 3,4-dihydro-2H-pyrrole-2-carbonitriles with copper(II)-salts furnished 2,2'-bipyrroles as well as 5,5'-bis(5-cyano-1-pyrroline…

SUBSTRATE-ELICITED DISSOCIATION OF THE ISOSAFROLE METABOLITE-CYTOCHROME P-450 COMPLEX AND THE CONSEQUENTIAL REACTIVATION OF MONOOXYGENATION

1977

ABSTRACT The present study was initiated to determine whether the substrate-elicited dissociation of the isosafrole metabolite-cytochrome P-450 complex resulted in increased monooxygenase activity. It was found that the substrates p -nitroanisole and ethoxycoumarin would elicit dissociation, furthermore this dissociation was accompanied by increased dealkylation of the substrates. Benzo(a)pyrene was found not to effect the dissociation of the complex, while biphenyl, which undergoes a similar hydroxylation, was effective.

ChemInform Abstract: Electrochemical Amination of Less-Activated Alkylated Arenes Using Boron-Doped Diamond Anodes.

2016

Induction of the alkyltransferase (MGMT) gene by DNA damaging agents and the glucocorticoid dexamethasone and comparison with the response of base ex…

1996

Repair of alkylated bases in DNA is performed by O6-methylguanine-DNA methyltransferase (MGMT) and a set of enzymes of the base excision repair pathway involving N-methylpurine-DNA glycosylase (MPG), apurinic endonuclease (APE), DNA polymerase beta (Pol beta) and DNA ligase. The level of expression of these enzymes may exert a profound effect on resistance of cells towards alkylating drugs. We have comparatively analyzed the expression of MGMT and the different base excision repair genes in rat hepatoma cells (line H4IIE) after exposure to alkylating agents, X-rays and the glucocorticoid hormone dexamethasone. Furthermore, the effect of these agents on the activity of the cloned human MGMT …

Molecular aspects of carcinogenesis. Part B

1989

Nitrogen mustards represent a major group of alkylating agents that are used in the chemotherapy of cancer. It is commonly accepted that they exert their cytotoxic effects by their ability to produce interstrand crosslinks in DNA. The main target site of the two identical alkylating moieties is the N-7 position of guanine. By a Maxam-Gilbert-type reaction it is possible to identify "hot spots" for alkylation by nitrogen mustards. Analysis of data obtained reveal the importance of the DNA context for efficient alkylation. For most of~ the compounds the highest reactivity is observed ila regions of G clusters, while in the neighbourhood of cytosine residues alkylation is reduced. As a consequ…

Reinvestigation of the synthesis and evaluation of [N-methyl-11C]vorozole, a radiotracer targeting cytochrome P450 aromatase

2009

Abstract Introduction We reinvestigated the synthesis of [ N -methyl- 11 C]vorozole, a radiotracer for aromatase, and discovered the presence of an N -methyl isomer which was not removed in the original purification method. Herein we report the preparation and positron emission tomography (PET) studies of pure [ N -methyl- 11 C]vorozole. Methods Norvorozole was alkylated with [ 11 C]methyl iodide as previously described and also with unlabeled methyl iodide. A high-performance liquid chromatography (HPLC) method was developed to separate the regioisomers. Nuclear magnetic resonance (NMR) spectroscopy ( 13 C and 2D-nuclear Overhauser effect spectroscopy NMR) was used to identify and assign s…

Synthesis of Multisubstituted 1,4-Dihydrobenzoxazin-2-ones through a One-Pot Nucleophilic N-Alkylation/C-Alkylation of Cyclic α-Imino Esters

2017

A nucleophilic N-alkylation of 2-oxobenzoxazine-2-carboxylates with organozinc reagents with good selectivities and in moderate to good yields is described. Moreover, the synthesis of multisubstituted 1,4-dihydrobenzoxazine-2-ones bearing a tetrasubstituted carbon atom via a one-pot N-alkylation/C-alkylation reactions is reported.

Orbital-controlled reactions catalysed by zeolites: Electrophilic alkylation of aromatics

1994

The role of orbital control in product selectivity during electrophilic aromatic alkylation catalysed by zeolites was studied both theoretically and experimentally. In order to discuss this, the alkylation of toluene and m-xylene by methanol was carried out on a series of large-pore zeolites (HY). The changes in the para to ortho ratio observed on changing the framework Si/Al ratio of the zeolites were related to ab initio molecular orbital calculations of the LUMO energy of structurally alike model clusters but containing different tetrahedral cations around the active site. The observed correlation is discussed in terms of the HSAB principle by taking into account the influence of the cat…

Darstellung von 1-(Piperidinyl-4)-indolinonen-(2) und -3,4-dihydrocarbostyrilen 3. Mitt.: Über potentielle Analgetika

1974

Nach reduktiver N-Alkylierung von 2-Amino-phenylessigsaureamid und 2-Amino-hydrozimt-saureamid mit N-substituierten Piperidonen-(4) konnten durch anschliesende interne Cyclisierung 1-(Piperidinyl-4)-indolinone-(2) und 1-(Piperidinyl-4)-3,4-dihydrocarbostyrile dargestellt werden. Synthesis of 1-(Piperidinyl-4)-indolinones-(2) and -3,4-dihydrocarbostyriles Reductive alkylation of 2-amino-phenylacetamide and 2-amino-phenylpropionamide with N-substituted piperidones-(4) gave by following internal cyclisation 1-(piperidinyl-4)-indolinones-(2) and 1-(piperidinyl-4)-3,4-dihydrocarbostyriles.

Influence of layer structure preservation on the catalytic properties of the pillared zeolite MCM-36

2010

MCM-36 is a catalytically active material made by swelling and subsequent pillaring of a layered zeolite precursor, MCM-22(P). However, the swelling procedures lead to significant destruction of layer structure and alteration of framework silicon/aluminum (Si/Al) ratio, which are likely to influence the acidity and catalytic activity of the final materials. We report a milder swelling and pillaring process to prevent such structural destruction. The resulting pillared materials show higher crystallinity and improved retention of the zeolitic layer structure when compared to the ones prepared by the previously reported methods involving more aggressive treatments. Implications of such struct…