- Quaternary N-(2-Pyridyl)-DABCO Salts: One-Pot in Situ Formation from Pyridine-N-oxides and Reactions with Nucleophiles: A Mild and Selective Route to Substituted N-(2-Pyridyl)-N′-ethylpiperazines
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The N-(2-pyridyl)-N′-ethylpiperazines are important structural motifs in several medicinally relevant compounds. Known synthetic methods toward these structures are multistep and generally based on the SNAr-chemistry; their applicability is significantly limited to substrates containing electron-withdrawing groups. Here, we describe a new methodology for a rapid and modular access to this privileged scaffold. Importantly, the developed protocol proved to be very general and efficient for the substrates containing substituents of different electronic nature. An operationally simple, metal-free, one-pot synthetic procedure involves the initial reaction of activated heterocyclic N-oxides with DABCO, followed by in situ treatment of the resultant quaternary N-(2-pyridyl)-DABCO salts with nucleophiles, resulting in ring-opening. The method features mild reaction conditions, high positional selectivity, and excellent functional-group tolerance. The utility of our approach is demonstrated by the late-stage site-selective functionalizations of complex molecules; a rapid modular assembly of MC2050, a potent PARP-1 inhibitor; and gram-scale preparations.
- Bugaenko, Dmitry I.,Yurovskaya, Marina A.,Karchava, Alexander V.
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- A new transformation of aminopyridines upon diazotization in acetonitrile with the formation of N-pyridinylacetamides
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Diazotization of aminopyridines upon treatment with NaNO2 and H3PO4 in acetonitrile led to the formation of N-pyridinylacetamides. This reaction constitutes a convenient and general preparative method for the synthesis of 2-, 3-, and 4-N-pyridinylacetamides under mild conditions in good yields. The in situ oxidation of the thus obtained N-pyridinylacetamides with hydrogen peroxide gave good yields of pyridinylacetamide N-oxides.
- Chudinov,Dovbnya,Krasnokutskaya,Ogorodnikov,Filimonova
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p. 2312 - 2314
(2017/05/12)
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- PYRROLOPYRIMIDINE DERIVATIVES AS MODULATORS OF MULTI-DRUG RESISTANCE (MDR)
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A compound which is a pyrrolopyrimidine of formula (I) wherein R1 is selected from H, Cl-C6 alkyl which is unsubstituted or substituted, (CH2)nAr1, (CH2)pNR4R5, halogen and (CH2)pX; R2 is CH2)pArl; R3 is selected from H, Cl -C6 alkyl which is unsubstituted or substituted, (CH2)pZ and (CH2)pArl; P is an unsaturated 5, 6, or 7 membered carbocyclic or heterocyclic ring which is unsubstituted or substituted; R4 and R5 which are the same or different are selected from H, Cl -C6 alkyl which is unsubstituted or substituted, (CH2)nC3-C10 cycloalkyl, (CH2)nAr1 , and (CH2)nOR6, or R4 and R5 together with the nitrogen atom to which they are attached, form a saturated five or six membered nitrogen containing heterocyclic ring which may contain one extra heteroatom selected from 0, N and S and which is unsubstituted or substituted; R6 is selected from H, Cl -C6 alkyl which is unsubstituted or substituted, C3-C10 cycloalkyl, (CH2)nOC1-C6alkyl which is unsubstituted or substituted, (CH2)nO(CH2)nAr1 , (CH2)nCO2C1-C6,alkyl which is unsubstituted or substituted and (CH2)nAr1; X is selected from CN, azide, (CH2)nNHSO2R6 and (CH2)nNHCOR6; Z is selected from CN, CO2R6 and CONR4R5; Ar1 is the same or different when more than one is present within a given substituent group and is an unsaturated C6-C10 membered carbocylic group or an unsaturated 5-11 membered heterocycle, either of which is unsubstituted or substituted; p is an integer of 1 to 6; n is the same or different when more than one is present within a given substituent group and is 0 or an integer of 1 to 6; with the proviso that the pyrrolepyrimidine compound of formula (I) is other than 1-(4-benzyl-piperazin-1-yl)-9H-2,4,9-triaza-fluorene; and the pharmaceutically acceptable salts thereof, have activity as inhibitors of MRP (multidrug resistant protein) and may thus be used to modulate multidrug resistance, for instance in potentiating the cytotoxicity of a chemotherapeutic agent.
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- An Excellent Method for the Mild and Safe Oxidation of N-Heteroaromatic Compounds and Tertiary Amines
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Selective, mild and safe N-oxidation of N-heteroaromatic compounds and tertiary amines affording high product yields was achieved by using the H2O2-urea/phthalic anhydride system. Key Words: N-Oxidation / Hydrogen peroxide / Urea / Phthalic anhydride
- Kaczmarek, Lukasz,Balicki, Roman,Nantka-Namirski, Pawel
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p. 1965 - 1966
(2007/10/02)
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