1- nitro-l-cyclohexene

As the last example of this section, a conjugate addition sequence of Ikeda and coworkers will be discussed, in which a somewhat unusual Michael system 2-26 was used (Scheme 2.6) [11]. Reactions of 1-nitro-l-cyclohexene (2-26) and 4-hy-droxybutynoates 2-27a-c in the presence of the base KOtBu gave R/Z-mixtures of substituted octahydrobenzofurans 2-28a-c in excellent to good yield. 

An example of the usefulness of the methodology was the new industrial route to cyclohexanone oxime developed by Corma and Serna, a process which is based on the selective hydrogenation of 1-nitro-l -cyclohexene by gold nanoparticles supported on Ti02 or Fe203 [220]. 

A similar large reduction in rate was observed in going from cyclohexene to 1-nitro-l-cyclohexene. Similarly, substituting a hydrogen atom by an electron-donating methyl group at the double bond site in cyclopentene and cyclohexene enhances the reactivity in comparison to the unsubstituted cycloalkene. The presence of substituents at sites remote from the double bond has little effect on the reactivity as can be seen by comparing the Arrhenius parameters for cyclohexene and 4-methyl-1-cyclohexene. 

Compounds that increase the resistance to oxidative stress were identified by their ability to increase the IC50 of the human neuronal cell line IMR-32 for hydrogen peroxide (Fiander and Schneider 1999). All of the compounds identified that increased the IC50 (238 53% by 2 pM 1-nitro-l-cyclohexene 172 51% by 2 iM 3-methylene-2-norbornanone) also increased the specific activity of glutathione S-transferase. In addition, compound-caused increases in the specific activity of glutathione S-transferase correlated with compound-caused increases in the IC50, the expected behaviour if glutathione S-transferase was a critical enzyme. 

Trimethylsilyloxy-cyclohexen reagiert mit Nitronimn-tetrafluoroborat in Acetonitril bei — 25° mit 47% Ausbeute zu 2-Nitro-l-oxo-cyclohexan2 (mit Nitryl-chlorid wird dagegen... 

In analoger Weise erhalt man aus l,3-Dimethyl-2-trimethylsilyloxy-cyclohexen 2,6-Dime-thyl-2-nitro-l-oxo-cyclohexan (41%) bzw. aus 1-Trimethylsilyloxy-cyclopenten 2-Nitro-l-oxo-cyclopentan2 (95%). 

Die Uberfuhrung von 1-Acetoxy-cyclohexen zu 2-Nitro-l-oxo-cyclohexan gelingt am be-sten, wenn man geringe Mengen Schwefelsaure zu einem Salpetersaure/Acetanhydrid-Gemisch (Acetyl-nitrat) gibt (86% )2 ... 

Analog erhalt man mit 1-Nitro-cyclohexen 9-Hydroxy-9-methyl-8-morpholino-l-nitro-bi-cyclo[4.3.0]non-7-en (Schmp. 180— 182°)1 ... 

Cyclohexen 4-methoxycarbonyl-l-nitro- E15/1, 1192 (H N02) Cyclopentan 1-Ethoxycarbonyl-l-nitroso-2-oxo- X/l, 912... 

Cyclohexan 1-Cyan-l-ethoxycarbo-nyl-2-methyl- EI9a, 668 (Disaure + Cyclohexan) Cyclohexen 4-Morpholinocarbo-nyl- E5,937 (CHO - CO-NR2) Cyeloocten l-(2-Nitro-allyl)- E15/I, 1165 (En —N02 + R2CH-X) Ethan 2-(3,4-Dimethoxy-phenyl)-1-methylamino- XI/1, 957 Furan... 

Reaction of the anion of 2-nitropropane (10 mmol) with 3-bromo-l-nitrocyclohex-l-ene (1) (5 mmol) in dimethylformamide under nitrogen with light irradiation (two 150-W tungsten white light lamps) leads to 1-nitro-e.xo-6-(l-methyl-1-nitro-ethyl)bicyclo[3.1. OJhexanc (2) as the only major product in addition to traces of impurities. None of the expected substitution product l-nitro-3-(l-methyl-l-nitroethyl)cyclohexene is obtained.91... 

Oxo-l,3-bis-[4-methoxy-phenyl]- 70 3-Oxo-l-[cyclohexen-(l)-yl]-3-phenyl- 459 3-Oxo-1.3-dipheny1- 71, 623 3-Oxo-3-phenyl-l-furyl-(2)- 438 3-Oxo-1-phenyl-3-(2-nitro-phenyl)- 606 1-Oxo-3-phenyl-l-pyridyl-(2)- /64... 

Dimethyl-5,7-dioxo-2-phenyl-l, 4-oxazepan laBt sich mit 1 -Nitro-cyclohexen in Gegen-wart von Basen und anschlieBender Verseifung zu chiralen (2-Nitro-cyclohexyl)-essig-sauren umsetzen30 ... 

Bis- 3-(bzw.4)-[2,2-dimethyl-2-(2-hydroxy-propyl)-1 -dehydro-hydrazinocarbonyl]-phenyl - 687 Bis-[2-methy]-phenyl]- 538 -bis-phosphonsaure-diester 523 Bis-[trifluormethy]]- 538 tert.-Butyl-( 1-hydroperoxy-cyclopentyl)- 571 tert.-Butyl-( 1 -hydroxy-cyclopentyl)- 571 (4-Chlor-phenyl)-(2-nitro-phenyl)- 693 (4-Chlor-phenylthio)-(4-nitro-phenyl)- 700 [Cyclohexen-(l)-yl]-phenyl- 368 Diaryl- 550, 552, 558, 567 Diphenyl-... 

Induziert durch einen OberschuB an Dichlor-diisopropyloxy-titan reagieren verschiedene -Nitro-1-alkene mit 1-Trimethylsilyloxy-cyclohexen in Dichlormethan bei — 90° zu bicyclischen Nitronaten, die mit katalytischen Mengen an Kaliuinfluorid in Methanol anti- bzw., syrt-2-(2-Nitro-ethyl)-l-oxo-cyclohexane liefem (55-81%)4 ... 

Propane 3-Nitro-2-(2-oxo-cyclo-hexyl)-l.1.1-lrifluoro- ElOb,. 461 (F,C-CN2- Cll,-NO, + 1-NR2 cyclohexen)... 

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