Steroid nitrogen compounds. III.11For paper II see ref. 2. A general method for introduction of O, N, S and other functionality into position-5 of cholestanes. conjugate addition of nucleofhiles to 6-nitrosocholesteryl acetate generated in situ from the 5α-chloro-6-oxime

Komeichi, Toshihisa; Iwasaki, Takaya; Ito, Yoshihiro; Aida, Fumio

doi:10.1016/0039-128x(72)90026-8

Cited by 5 publications

(6 citation statements)

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Section: (41)mentioning

confidence: 99%

“…Others have been prepared in the gaseous state using flow techniques, and the identification of the short-lived nitrosoethenes has been accomplished by microwave spectroscopy. [390][391][392][393][394] The bases used for dehydrohalogenation of the chlorooximes include triethylamine, 395 1,5-diaza-bicyclo[4,3,0]non-5-ene, 396 sodium alkoxides, 397 stirring a suspension of freshly ground sodium carbonate suspended in dry tert-butyl methyl ether 398 (or in diethyl ether 399 or methylene chloride 400 ), a two-phase system of aqueous sodium carbonate and methylene chloride, 401 stirring with sodium bicarbonate in alcohol, 402 and stirring with calcium hydroxide suspended in ethyl acetate containing 0.5% water. 403 For the synthesis of gaseous nitrosoalkenes, the chlorooxime is passed over sodium bicarbonate or potassium carbonate at room temperature, 392,394 although direct dehydrochlorination by pyrolysis at 450 °C is preferred.…”

Section: Dehydrohalogenation Of R-halooximes and Chloronitrosoalkanesmentioning

confidence: 99%

“…403 For the synthesis of gaseous nitrosoalkenes, the chlorooxime is passed over sodium bicarbonate or potassium carbonate at room temperature, 392,394 although direct dehydrochlorination by pyrolysis at 450 °C is preferred. [390][391][392][393] Dehydrochlorination of chlorooximes by triethylamine in organic solvents such as benzene, 404 DMF, 395 or acetonitrile 405 results in rapid generation of nitrosoalkenes. Dehydrochlorination of dimeric vicinal chloronitroso compounds by triethylamine has been employed by Pritzkow [406][407][408][409][410][411] for the preparation of a wide variety of β-nitrosostyrenes.…”

Section: Dehydrohalogenation Of R-halooximes and Chloronitrosoalkanesmentioning

confidence: 99%

“…Others have been prepared in the gaseous state using flow techniques, and the identification of the short-lived nitrosoethenes has been accomplished by microwave spectroscopy. − The bases used for dehydrohalogenation of the chlorooximes include triethylamine, 1,5-diaza-bicyclo[4,3,0]non-5-ene, sodium alkoxides, stirring a suspension of freshly ground sodium carbonate suspended in dry tert- butyl methyl ether (or in diethyl ether or methylene chloride), a two-phase system of aqueous sodium carbonate and methylene chloride, stirring with sodium bicarbonate in alcohol, and stirring with calcium hydroxide suspended in ethyl acetate containing 0.5% water . For the synthesis of gaseous nitrosoalkenes, the chlorooxime is passed over sodium bicarbonate or potassium carbonate at room temperature, , although direct dehydrochlorination by pyrolysis at 450 °C is preferred. − Dehydrochlorination of chlorooximes by triethylamine in organic solvents such as benzene, DMF, or acetonitrile results in rapid generation of nitrosoalkenes. Dehydrochlorination of dimeric vicinal chloronitroso compounds by triethylamine has been employed by Pritzkow − for the preparation of a wide variety of β-nitrosostyrenes.…”

Section: 101 Dehydrohalogenation Of α-Halooximes and Chloronitrosoalk...mentioning

confidence: 99%

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Preparations ofC-Nitroso Compounds

2004

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Section: (41)mentioning

confidence: 99%

Section: Dehydrohalogenation Of R-halooximes and Chloronitrosoalkanesmentioning

confidence: 99%

Section: Dehydrohalogenation Of R-halooximes and Chloronitrosoalkanesmentioning

confidence: 99%

“…Others have been prepared in the gaseous state using flow techniques, and the identification of the short-lived nitrosoethenes has been accomplished by microwave spectroscopy. − The bases used for dehydrohalogenation of the chlorooximes include triethylamine, 1,5-diaza-bicyclo[4,3,0]non-5-ene, sodium alkoxides, stirring a suspension of freshly ground sodium carbonate suspended in dry tert- butyl methyl ether (or in diethyl ether or methylene chloride), a two-phase system of aqueous sodium carbonate and methylene chloride, stirring with sodium bicarbonate in alcohol, and stirring with calcium hydroxide suspended in ethyl acetate containing 0.5% water . For the synthesis of gaseous nitrosoalkenes, the chlorooxime is passed over sodium bicarbonate or potassium carbonate at room temperature, , although direct dehydrochlorination by pyrolysis at 450 °C is preferred. − Dehydrochlorination of chlorooximes by triethylamine in organic solvents such as benzene, DMF, or acetonitrile results in rapid generation of nitrosoalkenes. Dehydrochlorination of dimeric vicinal chloronitroso compounds by triethylamine has been employed by Pritzkow − for the preparation of a wide variety of β-nitrosostyrenes.…”

Section: 101 Dehydrohalogenation Of α-Halooximes and Chloronitrosoalk...mentioning

confidence: 99%

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Preparations ofC-Nitroso Compounds

2004

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“…Usually the cyanoximes are obtained from ketonitriles [4,7,8] or enaminonitriles [1] and hydroxylamine, and also by reduction of β-nitrocyanides [9]. At the same time there are only few known examples of their preparation from β-nitroso chlorides and inorganic cyanides [10][11][12][13].…”

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Synthesis and properties of vicinal cyanoximes of adamantane series

2015

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1,4-Addition of cyanide ion to conjugated nitrosoalkenes of adamantane series, generated in situ from dimers of 2-alkylideneadamantanes nitroso chlorides or from α-chloro-oxime, results in vicinal cyanoximes. Proceeding from the latter approaches to some 2,2-disubstituted adamantanes were developed.The presence of two reactive groups in the structure of vicinal cyanoximes makes them promising synthons in heterocyclization processes. Examples are known of applying β-cyanoximes in the preparation of 5-aminoisoxazoles [1, 2], including the condensed ones [3], and also the derivatives of indole [4], azarine [5], 5-amino-1,3-oxazole, pyrrolidinone, and oxazolo[5,4-b]-pyridine [6]. Usually the cyanoximes are obtained from ketonitriles [4, 7, 8] or enaminonitriles [1] and hydroxylamine, and also by reduction of β-nitrocyanides [9]. At the same time there are only few known examples of their preparation from β-nitroso chlorides and inorganic cyanides [10-13].In extension of investigations on the chemical properties of nitroso chlorides of adamantane series [14-16] we studied the reaction of dimeric nitroso chlorides of 2-alkylideneadamantanes 1a and 1b or chloro-oxime 2 with excess of sodium cyanide in DMF that resulted in vicinal cyanoximes 3a-3с (Scheme 1) in high yield.The reaction mechanism evidently includes the generation of unstable nitrosoalkenes A [17,18], then the cyanide ion adds to them by Michael reaction. In the IR spectra of cyanoderivatives 3а-3с characteristic absorption bands are present at 2230-2245 cm -1 , corresponding to vibrations of the cyano group. In 13 С NMR spectra the atoms of carbon of cyano and oxime groups appear in the region 121.0-122.2 and 149.9-158.5 ppm respectively. The hydrogen atom of the hydroxy group of oxime fragment is detected in 1 Н NMR spectra at 8.05-8.51 ppm. (in CDCl 3 solution).Treating α-cyanoxime 3а with thionyl chloride in the presence of triethylamine afforded adamantane-2,2-dicarbonyl 4. Amide of 2-cyano-2-adamantanecarboxylic acid 5 was obtained by heating α-cyanoxime 3а in DMF above 130°С (Scheme 2). Since no acid catalyst is present the generation of amide 5 cannot result from Beckmann rearrangement that also should have provided a substituted formamide of oxime 3a of Е-configuration.We assume that first the isomerization of oxime in Z-form occurs. Such process may proceed in DMF at high temperature because the barrier to E,Z-isomerization in oximes is relatively low [19]. Further as

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Synthesis of trialkylsiloxy‐substituted and other 5,6‐dihydro‐4H‐1,2‐oxazines by hetero diels‐alder reactions of nitroso alkenes — Preparative scope and diastereoselectivity

Hippeli

Reißig

1990

Liebigs Ann. Chem.

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A variety of 5,6-dihydro-4H-1,2-oxazines 3 and 4 is prepared in good yields from silyl enol ethers 1 and nitroso alkenes 2a or 2b, respectively. A systematic variation of substituents reveals preparative scope and limitations of this hetero DielsAlder reaction with inverse electron demand. The cycloaddition is rather sensitive with regard to steric effects -in particular, large groups at C-1 of the silyl enol ethers 1 completely prevent the reaction. On the other hand, excellent diastereoselectivities are observed employing appropriately substituted olefins. The presented method for the synthesis of 1,2-oxazines also displays high regio-and periselectivity as is demonstrated by transformations l r -+ 3 r and 13-14.The chemistry of six-membered heterocycles exhibiting general structure A (1,2-oxazines) and incorporating an N -0 moiety is much less developed than that of the lower homologues (isoxazole derivatives). This is surprising since class A compounds might have interesting biological activities2' or other valuable properties. They can also display considerable synthetic potential as has been shown for 3,6-dihydro-2H-1,2-oxazines B by Kresze's group3). Synthesis and preparative use of 5,6-dihydro-4H-l,2-oxazinium salts C were advanced by Eschenmoser and coworkers4). A B C D E FIn this account and following papers we will deal with the chemistry of 5,6-dihydro-4H-1,2-oxazines D -from now abbreviated as 1,2-oxazines. Although single ld-oxazines can be prepared by cyclization of y-halogenated oximes, a retrosynthetic analysis shows that a [4 + 21 cycloaddition of olefins E and nitroso alkenes F should be a suitable and highly flexible route to heterocycles D. Indeed this approach was first realized by Bravo et al.') and was further developed by Viehe6) and mainly Gilchrist'! Their results') clearly demonstrate that this reaction can be classified as a Diels-Alder reaction with inverse electron demand9'.However, the potential of 1,2-oxazines D for (stereoselective) synthetic applications was not investigated in much detail''). We were intrigued by the attractive goal to prepare cyclic or acyclic 1,4-difunctionalized compounds G and H from D -as has been advanced with great success in the isoxazole field generating 1,3-difunctional systems 'I). Therefore we undertook a systematic study to explore scope and limitations of the [4 + 23 cycloaddition of nitroso alkenes F and the transformations of the resulting 1,2-oxazines D.

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Steroid nitrogen compounds. III.11For paper II see ref. 2. A general method for introduction of O, N, S and other functionality into position-5 of cholestanes. conjugate addition of nucleofhiles to 6-nitrosocholesteryl acetate generated in situ from the 5α-chloro-6-oxime

Cited by 5 publications

References 12 publications

Preparations ofC-Nitroso Compounds

Preparations ofC-Nitroso Compounds

Synthesis and properties of vicinal cyanoximes of adamantane series

Synthesis of trialkylsiloxy‐substituted and other 5,6‐dihydro‐4H‐1,2‐oxazines by hetero diels‐alder reactions of nitroso alkenes — Preparative scope and diastereoselectivity

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