摘要:

Generation ofN,N‐Disubstituted Iminium Salts by Application of Silane Reagents(Dialkylamino)trimethylsilanes, halotrimethylsilanes and trimethylsilyl triflate proved to be superior reagents for a convenient access to the title compounds in an aprotic medium. In most cases, the co‐formation of silylethers or disiloxanes acts as driving force. A comprehensive overview on this field, including the latest findings, is given and the significant mechanistic relationships are illuminated. The three component synthesis starting from carbonyl compounds (Scheme 3) and the two component synthesis (“latent” three component synthesis) starting from α‐chloroethers (Schemes 16, 19) hold a central position. The latter method offers special advantage for the entrance into the multifunctional series, as shown by the first synthesis of vinylogous Viehe salts as preparatively useful C3‐building blocks (Schemes 17, 22, 23). As an aim, this report should stimulate further progress in

ISSN:0941-1216    

DOI:10.1002/prac.19983400402

出版商:WILEY‐VCH Verlag GmbH    

年代:1998

数据来源: WILEY

摘要:

Abstract1,3‐Diaza‐2‐azoniaallene salts R1‐NN+NR26 represent a new functional group. 1,3‐Disubstituted triazenes8are oxidized withtert‐butyl hypochlorite to stable open‐chainN‐chlorotriazenes R1NNNClR29, which at low temperatures with Lewis acids afford the reactive intermediates6. The salt6ais stable below −50 °C and was characterized by spectroscopic and analytical data. Heterocumulenes6behave as positively charged 1,3‐dipoles undergoing cycloadditions to many different multiple bonds to furnish 1,2,3‐triazolium and tetrazolium salts,e.g.to both electron‐rich and electron‐deficient alkenes, alkynes, to one or both double bonds of 1,3‐butadienes, to carbodiimides, and cyanamides (1,3‐dipolar cycloaddition with inverse electron demand). With an allene, a butatriene and a pentatetraene the 4,5‐dihydro‐1H‐1,2,3‐triazolium salts17–19were obtained. The constitutions of four of the products were secured by X‐ray structural analyses. 4,5‐Dihydro‐1H‐1,2,3‐triazolium salts11and 1H‐1,2,3‐triazolium salts20

ISSN:0941-1216    

DOI:10.1002/prac.19983400403

出版商:WILEY‐VCH Verlag GmbH    

年代:1998

数据来源: WILEY

摘要:

AbstractCyclization reactions of 2‐vinylaniline derivatives, proceedingviaanils, amides, imidic acid esters, ureas, thioureas, carbodiimides, formamidine ylids, sulfonamides or ketenes, leading to quinoline or indole derivatives, are described. In a short introduction interesting results from the literature, excluding our results, are presented. In the centre of this progress report our results on acid catalyzed reactions of 2‐vinylanilines with aldehydes and ketones are discussed in a more detailed man

ISSN:0941-1216    

DOI:10.1002/prac.19983400404

出版商:WILEY‐VCH Verlag GmbH    

年代:1998

数据来源: WILEY

摘要:

AbstractCopper‐catalyzed alkoxycarbonylcarbene transfer from methyl ortert‐butyl diazoacetate to acyclic enaminoesters6a,band enaminocarboxanilide13yields vicinal push‐pullsubstituted cyclopropanes7a,b,8, and14. In contact with dry silica gel, the latter compounds undergo facile ring‐opening leading to enaminoesters9, 10, and15. Treatment with aqueous acid transforms9and10into 2‐acylsuccinates11and12, and15into pyrrolinone16. Methoxycarbonylcarbene transfer to enaminoketones1a–cdoes not yield isolable cyclopropanes, but after hydrolytic work‐up α‐acyl‐γ‐ketoe

ISSN:0941-1216    

DOI:10.1002/prac.19983400405

出版商:WILEY‐VCH Verlag GmbH    

年代:1998

数据来源: WILEY

摘要:

Stable Tetraazafulvalenes – Syntheses and ChemistryThe syntheses, properties and reactions are described for 1,3,6,7‐tetrakis[arylamino]‐1,4,5,8‐tetraazafulvalenes and their vinylogous derivatives. First, the acylation of form‐ as well as acetamidine with bis‐imidoylchlorides derived from oxalic acid6formed reactive cyclic intermediates which dimerized to tetraazafulvalenes12or bisvinylogous tetraazafulvalenes14. Based on, a further synthesis was found using a cycloacylation reaction of amidines with imidoylchlorides6followed by prototropic migration of α‐hydrogen. Thus, the vinylogous compound15and the phenylogous derivatives16, 17could be isolated in moderate up to good yields. Besides amidines, other derivatives of carboxylic acids as amides or thioamides could be transformed into corresponding tetraazafulvalenes18–20. Due to their vicinal amino groups, alkylation and acylation reactions were studied. For example, the reaction with orthoformates yielded the ring fused products24a,bwhich may be starting material for carbenes just as the cyclization product with thiophosgene27. Treatment of tetraazafulvalenes with anhydrous iron‐II salts or molybdenum hexacarbonyl yielded the deeply colored metal diazadiene complexes33and34. Finally, reduction using metallic lithium and subsequent alkylation constitutes a convenient synthetic entry to heterocyclic analo

ISSN:0941-1216    

DOI:10.1002/prac.19983400406

出版商:WILEY‐VCH Verlag GmbH    

年代:1998

数据来源: WILEY

摘要:

AbstractThe 2(3)‐formyl‐glycals2, 4, 6react with hydrazine hydrate to furnish theC‐(1H‐pyrazol‐3‐yl)alditoles7, 8, 9. Treatment of2, 4, 6with cyanoacetamide provides the 2(3)‐(2‐aminocarbonyl‐2‐cyano‐vinyl)‐1,5(2,6)‐anhydro‐2(3)‐deoxy‐hex‐enitols10, 13, 15, which are converted into the polyhydroxyalkyl 2‐amino‐nicotinamides11, 14, 16and

ISSN:0941-1216    

DOI:10.1002/prac.19983400407

出版商:WILEY‐VCH Verlag GmbH    

年代:1998

数据来源: WILEY

摘要:

Abstract7‐Methyloctahydroacridines7a–dwere obtained by a one‐pot imine condensation/Lewis acid‐catalyzed cyclization from aniline derivatives5a–dand aldehyde6. Only those compounds7could be oxidized with DDQ to the corresponding octahydroacridine‐7‐carbaldehydes9, which bear ameta‐chloro or bromo substituent (with respect to the methyl group) in addition to thepara‐amino group (i.e.7c,d→9c,d). Aldehyde9cwas further converted to the novel tripodand11which was characterized by X‐ray cryst

ISSN:0941-1216    

DOI:10.1002/prac.19983400408

出版商:WILEY‐VCH Verlag GmbH    

年代:1998

数据来源: WILEY

摘要:

Iminium Salts in Quantitative Gas/Solid and Solid/Solid ReactionsIminium salts that are highly susceptible to hydrolysis are quantitatively prepared and reacted in the solid state without solvents or liquid phases. Atomic force microscopy AFM helps in elucidating the mechanism of these still unusual gas‐solid and solid‐solid syntheses by recording surface topographies of reacting crystals ofL‐histidine(10)and triphenylverdazyl(15). Various imines add gaseous HCl or HBr to form stable iminium halides(1, 3, 4, 5, 11)even if frozen liquids of very weak heterocyclic bases are treated at low temperatures. Another way for quantitative yields of iminium salt hydrates(6)starts with solid primary ammonium halides and gaseous acetone.o‐Phenylenediamines(7)give quantitatively 1,5‐benzodiazepines(9)by solid state cyclization of bis‐iminium salt intermediates(8). Crystalline nitroxyls(12)and triphenylverdazyl(15)undergo stoichiometric one‐electron transfer with gaseous NO2or XeF2to give nitrosonium(14)and azonium salts(17). The solid state chlorination of tetramethylthiuramdisulfide(18)or dimethylthiocarbamoylchloride(20)yields phosgene dimethyliminiumchloride (Viehe salt21) in quantitative yield. Solid Viehe salt is quantitatively treated with gaseous Cl2to give the trichloride19and solid SbCl5or PCl5to produce the hexachloroantimoniates(22), ‐phosphates(23). Solid brenzcatechol(24), mercaptobenzimidazole(27),p‐nitroaniline(30),N‐methylbenzothiazolone‐2‐hydrazone(34)and acetophenone(41)are treated with21to give the corresponding chloroiminium salts(25, 28, 31, 35, 43).p‐Toluenesulfonamide(37)and22give the chloroiminium salt38. These quantitative solid‐solid reactions are most easily run in ball mills with cooling device. The “waste‐free” techniques achieve exclusion of moisture in an elegant way. The preparative use of the versatile products with nucleophiles is indicated. The three‐step s

ISSN:0941-1216    

DOI:10.1002/prac.19983400409

出版商:WILEY‐VCH Verlag GmbH    

年代:1998

数据来源: WILEY

摘要:

AbstractAnnulated Aminocyclopropane‐endo‐carbonitriles11a,bare reductively decyanated by sodium in liquid ammonia with complete retention of configuration. An additionally existing chlorine atom in the starting materials12a,c–e, thereby, is simulataneously replaced by hydrogen. The preparative advantage of this method is demonstrated by the selective access to 6α‐H‐isomers13band13eas members of the ensemble of bicyclo[3.1.0]hexanediyl‐dimorpholine diastereomers. A strong buckled bicyclohexane unit is present in 3α,6αisomer13eas indicated by1H NMR spectroscopy and X‐ray str

ISSN:0941-1216    

DOI:10.1002/prac.19983400410

出版商:WILEY‐VCH Verlag GmbH    

年代:1998

数据来源: WILEY

摘要:

Abstract4,5‐DisubstitutedN‐phenyl‐isothiazolium salts1with active 5‐methyl group react under the influence of anilines to form 3,4‐disubstituted isothiazolium salts3. The influence of donor and acceptor substituents in the 2‐phenyl group of1a–hand in the anilines2on the ring transformation were studied. The structure of the new salts was confirmed by X‐ray analysis. The 3‐hydroperoxy‐2,3‐dihydro‐isothiazole 1,1‐dioxides (12a,d) and the isothiazole‐3(2H)‐one 1,1‐dioxides (14a,d) are obtained

ISSN:0941-1216    

DOI:10.1002/prac.19983400411

出版商:WILEY‐VCH Verlag GmbH    

年代:1998

数据来源: WILEY