- Inactivation of Cytochrome P-450 by a Catalytically Generated Cyclobutadiene Species
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2,3-Bis(carbethoxy)-2,3-diazabicyclohex-5-ene (DDBCH), synthesized by a route analogues to that reported for the preparation of the bis(carbomethoxy) analogue, inactivates the phenobarbital-inducible cytochrome P-450 isozymes of rat liver in a time-, NADPH-, and oxygen-dependent manner.The enzymes are protected by carbon monoxide and competitive alternative substrates but not by glutathione.The cyclobutenyl ? bond and the diazabicyclo skeleton are required for destructive activity, but hydrolytic removal of the carbamate groups is not.Enzyme inactivation reflects alkylation of the prosthetic heme group of the enzyme by a catalytically generated reactive species.The alkylated prosthetic group has been isolated and has been characterized, after demetallation and esterification, as N-(2-cyclobutenyl)protoporphyrin IX.The N-alkyl group is primarily located on the nitrogen of pyrrole ring D.DDBCH is thus oxidized by cytochrome P-450 to a cyclobutadienoid species that alkylates the prosthetic heme group.
- Stearns, Ralph A.,Montellano, Paul R. Ortiz de
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- Homogeneous isomerization of 1,2-dicarbethoxy-1,2,3,6-tetrahydropyridazine by ruthenium complexes
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N-protected 1,2,3,4-tetrahydropyridazines are readily obtained from the corresponding 1,2,3,6-tetrahydro-derivatives by double bond migration induced by ruthenium complexes.Almost quantitative conversions and complete chemioselectivities are achieved using RuCl2(PPh3)4 as catalyst precursor at 100 deg C in a pressure vessel.In the same conditions the cluster complex H4Ru4(CO)12 shows lower activity, while HRh(PPh3)4 gives unsatisfactory results.
- Menchi, Gloria,Matteoli, Ugo,Scrivanti, Alberto,Paganelli, Stefano,Botteghi, Carlo
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- β-ELIMINIERUNG AN QUARTAEREN HYDRAZINIUMSALZEN, EINE NEUE METHODE ZUR DARSTELLUNG UNSYMMETRISCH ALKYLIERTER DIAMINE
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Deprotonation of the hydrazinium salts 5-8 with concomitant N-N cleavage resulted in the formation of imines, which were trapped by external nucleophiles.
- Askani, R.,Mueller, K. M.
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p. 5641 - 5644
(2007/10/02)
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