- Heterocyclic spirocyclohexadienones, I
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The compound formerly described as methylene amine 3 is in fact the heterocyclic spirocyclohexadienone 9. Contrary to literature, catalytic hydrogenation does not lead to methylamine 4 but to spiroketone 10 and a mixture of diastereomeric spirocyclic alco
- Mohrle,Schake,Bluhme-Hensen
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Read Online
- Bridging amines with CO2: Organocatalyzed reduction of CO2 to aminals
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The four-electron reduction of CO2 in the presence of secondary aromatic amines is described for the first time to access aminals. Under metal-free hydrosilylation conditions, the four C-O bonds of CO2 are cleaved, and the organocatalysts are able to balance the reactivity of CO2 to promote the selective formation of two C-N and two C-H bonds. The methodology enables the formation of various symmetrical and unsymmetrical aminals.
- Frogneux, Xavier,Blondiaux, Enguerrand,Thuéry, Pierre,Cantat, Thibault
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p. 3983 - 3987
(2015/11/11)
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- A general catalytic methylation of amines using carbon dioxide
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Putting CO2 to work: Carbon dioxide is shown to be a general and selective methylating reagent for secondary and primary, aromatic and aliphatic amines under reductive conditions. A variety of tertiary amines are obtained from CO2 and commercially available silanes in high yields with good tolerance to nitrile, olefin, ether, ester, and hydroxy groups. Copyright
- Li, Yuehui,Fang, Xianjie,Junge, Kathrin,Beller, Matthias
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supporting information
p. 9568 - 9571
(2013/09/23)
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- C-H activation with elemental sulfur: Synthesis of cyclic thioureas from formaldehyde aminals and S8
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The C-H activation of cyclic formaldehyde aminals LCH2 (L = RNCH2CH2CH2-NR and RNCH2CH2-NR, R = Me, Et, iPr, tBu, or Ph) with S8 proceeds at unusually low temperatures (T 2S. The reaction constitutes a new, solvent-free method for the synthesis of thioureas that eliminates the toxic and highly flammable CS2. For R = tBu, the ionic carbenium thiocyanates [LCH]+ SCN- dominate the product spectrum and the respective thioureas are obtained in low yield. The reactivity of the analogous sulfur and oxygen ring systems towards S8 was investigated. 1,3-Dithiolane is cleanly converted into 1,3-dithiolane-2-thione (S8, 14 d, 190°C) and resembles the cyclic formaldehyde aminals in this respect. 1,3-Dioxolane (L = OCH2CH2O) is completely inert towards sulfur even under forceful reaction conditions (190°C, 14 d). The formation of thioureas from aminals was investigated at the CBS-4 and B3LYP/6-31G(d) levels of theory.
- Denk, Michael K.,Gupta, Shilpi,Brownie, John,Tajammul, Sabiha,Lough, Alan J.
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p. 4477 - 4486
(2007/10/03)
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- Nucleophilic Addition to Substituted 1H-4,5-Dihydroimidazolium Salts
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1H-4,5-Dihydroimidazolium salts 1 react readily with nucleophilic reagents originating cyclic products which may be stable or become transformed into acyclic compounds maintaining the structural ethylenediamine unit. With methylmagnesium iodide compound le affords the expected imidazolidine, but in the case of substituted 1-aryl-3-methyl-2-phenyl salts 1b-d the N-aryl-N'-methylethylenediamines 3b-d and acetophenone (4) were isolated, the process representing the transfer of the C-2 unit to a nucleophilic carbon. With alkaline cyanides salts 1 react efficiently affording α,α-diaminonitriles 5. In these compounds the cyano group may be readily substituted by nucleophiles (hydroxyl anion, species with nucleophilic carbon and reagents that act by hydride ion transfer), in a way similar to the salts but with better yields.
- Salerno, Alejandra,Ceriani, Vanina,Perillo, Isabel A.
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p. 709 - 716
(2007/10/03)
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- Reduction of Substituted 1H-4,5-Dihydroimidazolium Salts
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Reactions of several substituted 1H-4,5-dihydroimidazolium salts 1 with nucleophilic and electrophilic reducing agents acting via hydride transfer were explored.Reaction of compounds 1 with lithium aluminum hydride in THF afforded the corresponding imidazolidines 2.When alkaline borohydrides (sodium borohydride, potassium borohydride, sodium cyanoborohydride) in ethanol at room temperature were used, partial or total over-reduction of compounds 2 leading to N,N,N'-trisubstituted ethylenediamines took place on occasion.Results may be explained taking into account that reductive cleavage of 2 proceeds via a stabilized iminium ion present in protic solvents.Treatment of compounds 1 with an excess of borane in THF afforded the corresponding imidazolidines 2 or their borane complexes, according to the substituent type.
- Salerno, Alejandra,Ceriani, Vanina,Perillo, Isabel A.
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p. 1725 - 1733
(2007/10/02)
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- A Stereochemical Investigation of 1,3-Diphenyl-4-methyl-1,3-diazolidines and its Related Compounds via NMR
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Four 1,3-diphenyl-4-methyl-1,3-diazolidines and two isomeric 2,5-diphenyl-3-methyl-1,2,5-thiadiazolidine 2-oxides were prepared.The pmr and cmr spectra of these compounds were obtained.On the basis of the chemical shifts due to the γ- and δ-effects, the stereochemical structures are discussed.
- Nishiyama, Tomihiro,Nanno, Yukio,Yamada, Fukiko
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p. 1773 - 1776
(2007/10/02)
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- Reduction of Cyclic Ureas with Lithium Aluminum Hydride
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A series of 1,3-dialkyl-2-imidazolidinones 1 and 1,3-dialklyltetrahydro -2(1H)-pyrimidinones 2 were reduced to the corresponding aminals 3 and 4, respectively, when treated with excess lithium aluminum hydride in ether.The rate of reduction is affected dr
- Bates, Hans Aaron,Condulis, Nicholas,Stein, Nora L.
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p. 2228 - 2229
(2007/10/02)
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- Synthesis of 1,3-Disubstituted Diazolidines
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Symmetrical and unsymmetrical 1,3-diaminoethanes 1 are obtained by the reduction of N,N'-disubstituted oxamides 4 with lithium aluminum hydride.The oxamides 4 are readily produced by treatment of diethyl oxalate with primary amines.The 1,3-diaminoethanes 1 lead to 1,3-diazolidines 2 on treatment with formaldehyde.
- Lambert, Joseph B.,Huseland, Dave E.,Wang, Gen-tai
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p. 657 - 658
(2007/10/02)
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- Extremely Reactive C=C-Double Bonds, IV. Unusual Reactions with Thiophenol, 1,2-Ethanedithiol, and other Sulfur Compounds
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Reactions of thiophenol and 1,2-ethanedithiol with imidazolidine derivatives lead to solvolysis with opening or conversion of the imidazolidine system as well as to hydrogenation, partly without a change in the ring system .Benzophenone diaryl dithioacetals are reduced to aryl benzhydryl sulfides by thiophenol . 1,1',3,3'-Tetraphenyl-Δ2,2'-biimidazolidine (9) desulfurates thioacetic acid, dibenzoyl disulfide, and dixanthogen .
- Schoenberg, Alexander,Singer, Erich,Stephan, Werner
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p. 3388 - 3399
(2007/10/02)
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- Extremely Reactive C=C-Double Bonds, II. 1,3-Diphenyl-2-imidazolidineselenone from 1,1',3,3'-Tetraphenyl-Δ2,2'-biimidazolidine and Selenium
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1,1',3,3'-Tetraphenyl-Δ2,2'-biimidazolidine (1) reacts with metallic selenium to form 1,3-diphenyl-2-imidazolidineselenone (6).The actions of powdered copper, ethyliodide, thiophenol, phenyl magnesiumbromide, phenylisocyanate, and lithium alanate on 6 are described.Some of the unusual mechanisms of these reactions are discussed.
- Schoenberg, Alexander,Singer, Erich,Stephan, Werner
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p. 2068 - 2073
(2007/10/02)
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- Hydrogen Peroxide Oxidation of α-(N,N-Dialkyl)aminoketones
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α-(N,N-Dialkyl)aminoketones are fragmented oxidatively by hydrogen peroxide, leading to carboxylic acids and products derived from iminium intermediates.
- Wenkert, David,Eliasson, K. Margareta,Rudisill, Duane
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p. 392 - 393
(2007/10/02)
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- Light-induced Reactions of 2-(N-Alkyl-N-arylamino)acetophenones and Related Amino-ketones: Formation of 1,3-Diarylazetidin-3-ols
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On irradiation in ether, 2-(N-methylanilino)acetophenones, Ar1NMe-CH2COAr2 (Ar1,Ar2=Ph,Ph; Ph,p-MeO-C6H4; Ph,p-Ph-C6H4; p-Cl-C6H4,Ph; p-MeO-C6H4,Ph; and p-Me-C6H4,Ph), underwent type II cyclisation to isomeric 1,3-diarylazetidin-3-ols.A minor photoproduct was one of the two expected type II fission products, the corresponding acetophenone Ar2COMe.The second type II fission product, imine Ar1N=CH2, was not detected, but in three cases a 1,3-diarylimidazolidine, probably derived from this imine, was isolated.Similar results were obtained on irradiation of the related amino-ketones, 2-(N-methylanilino)-2'-acetonaphthone and 2-(N-methylanilino)-1-tetralone.Direct fission of the C-2-N bond occured on irradiation of 2-(N-methylanilino)indan-1-one and 2,2-dimethyl-2-(N-methylanilino)acetophenone. 2-(N-Alkylanilino)acetophenones, PhNR-CH2COPh (R=Et, Me2CH, and PHCH2), yielded complex mixtures on irradiation.
- Allworth, Keith L.,EI-Hamamy, Ahmad A.,Hesabi, Massoud M.,Hill, John
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p. 1671 - 1678
(2007/10/02)
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- Light-induced Reactions of Heteroaryl N-Methylanilinomethyl Ketones: Formation of 3-Heteroaryl-1-phenylazetidin-3-ols
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A series of heteroaryl N-methylanilinomethyl ketones, PhNMe*CH2COR (R=heteroaryl), were irradiated with ether as the solvent.The corresponding 3-heteroaryl-1-phenylazetidin-3-ols (type II cyclisation products) were formed when R was 2-furyl, benzofuran-2-yl, 2-thienyl, 1-methylpyrrol-2-yl, and 2,4-dimethylthiazol-5-yl, but such products were not isolated when R was pyrrol-2-yl or 3-pyridyl.In some cases, products formed via type II fission were obtained.
- Hesabi, Massoud M.,Hill, John,El-Hamamy, Ahmad A.
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p. 2371 - 2373
(2007/10/02)
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