Generation and cyclization of thiocarbonyl S‐ylides by reaction of diazocompounds with C‐sulfonyldithioformates

The unexpected 1,3‐benzodithiine derivatives 5b,c were obtained from the reactions of trimethylsilyldiazomethane 2 with C‐sulfonyldithioformates, bearing pentachlorophenylthio group, 1b,c via unprecedented cyclization of the transient thiocarbonyl ylides 4b,c . While the corresponding reaction with C‐sulfonyldithioformates, bearing phenylthio group, afforded 5a via [2 + 3]‐cycloadditive dimerization of a transient thiocarbonyl ylides 4a . Under the same reaction condition, C‐sulfonyldithioformates 1d–f react with diazomethane and/or phenyldiazomethane to afford the unsymmetrical 1,3‐dithiolane 7d,e and thiirane 8e,f derivatives, respectively. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:28–33, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20246     

Synthesis and antimicrobial evaluation of some 1,2,4‐triazole, 1,3,4‐oxa(thia)diazole,and 1,2,4‐triazolo[3,4‐b]‐1,3,4‐thiadiazine derivatives

3‐Methyl‐2‐benzofurancarboxylic acid hydrazide ( 2 ) reacts with carbon disulfide and pota‐ ssium hydroxide to give the corresponding potassium carbodithioate salt 3 . Treatment of the latter salt with hydrochloric acid, hydrazine hydrate, and with phen‐ acyl bromide afforded the corresponding 1,3,4‐oxadia‐ zole‐5‐thione 4 , 4‐amino‐1,2,4‐triazole‐5‐thione 5 , and thiazolidine‐2‐thione 9 derivatives, respectively. The reaction of either 1,3,4‐oxadiazole‐5‐thione 4 or 4‐amino‐1,2,4‐triazole‐5‐thione 5 with phenacyl bromide resulted in the formation of 1,2,4‐triazolo[3, 4‐b]‐1,3,4‐thiadiazine derivative 8 . Treatment of compounds 3 or 4 with hydrazonoyl halides 10a–d furn‐ ished the same 1,3,4‐thiadiazol‐2‐ylidene derivatives 11a–d . The 7‐arylhydrazono‐1,2,4‐triazolo[3,4‐ b ]‐1, 3,4‐thiadiazine derivatives 12a–d were obtained either by treatment of 4‐amino‐1,2,4‐triazole‐5‐thione 5 with hydrazonoyl halides 10a–d or by coupling of the 1,2,4‐triazolo[3,4‐b]‐1,3,4‐thiadiazine derivative 8 with diazonium salts. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:621–627, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20162     

The reaction of active and stabilized phosphonium ylides with α,β-unsaturated carbonyl compounds [1]

The active ketenylidene-(2a) or thioketenylidenetriphenylphosphoranes (2b) react with 2-benzylidene-1,3-indandione (1), 5-benzylidenebarbituric acid (11), and 4-benzylidene-1,2-diphenyl-3,5-pyrazolidinedione (16) to give the corresponding pyranones and thioxopyranones (3a,b, 12a,b) and (17a,b), respectively. On the other hand, compounds 1 and 11 can be converted by reaction with the stabilized alkylidenephosphoranes 4a–e into the phosphoranylidenes 6a–e and 13a–e. Moreover, the oxaphosphinins 8 or 14 and the oxazaphosphinins 10 or 15 were obtained when compounds 1 and 11 were allowed to react with the phosphorane 7 and the iminophosphorane 9, respectively. Some of these new organophosphorus compounds are found to have insecticidal and molluscicidal properties against cotton leafworm Spodoptera littoralis larvae and Biomphalaria alexandrina snails. © 1997 John Wiley, & Sons, Inc.     

Synthesis of Novel Pyridothienopyrimidines,Pyridothienopyrimidothiazines, Pyridothienopyrimidobenzthiazoles and Triazolopyridothienopyrimidines

The reaction of 3‐amino‐4,6‐dimethylthieno[2,3‐b]pyridine‐2‐carboxamide (1a) or its N‐aryl derivatives 1b‐d with carbon disulphide gave the pyridothienopyrimidines 2a‐d , whilst when the same reaction was carried out using N¹‐arylidene‐3‐amino‐4,6‐dimethylthieno[2,3‐b]pyridine‐2‐carbohydrazides (1e‐h) , pyridothienothiazine 3 was obtained. Also, refluxing of 1b‐d with acetic anhydride afforded oxazinone derivative 4 . Compounds 2a and 2b‐d were also obtained by the treatment of thiazine 3 with ammonium acetate or aromatic amines, respectively. When compound 2a was allowed to react with arylidene malononitriles or ethyl α‐cyanocinnamate, novel pyrido[3″,2″:4′,5′]thieno[3′,2′:4,5]pyrimido[2,1‐b][1,3] thiazines 5a‐c were obtained. Treatment of 2b‐d with bromine in acetic acid furnished the disulphide derivatives 6a‐c . U.V. irradiation of 2b‐d resulted in the formation of pyrido[3″,2″:4′,5′]thieno[3′,2′:4,5]pyrimido[2,1‐b]benzthiazoles 7a‐c . The reaction of 2a‐d with some halocarbonyl compounds afforded the corresponding S‐substituted thiopyrido thienopyrimidines 8a‐j . Compound 8b was readily cyclized into the corresponding thiazolo[3″,2″‐a]‐pyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidine 9 upon treatment with conc. sulphuric acid. Heating of 2a,b with hydrazine hydrate in pyridine afforded the hydrazino derivatives 11a,b . Reaction of ester 8c with hydrazine hydrate in ethanol gave acethydrazide 10 . Compounds 10 and 11a,b were used as versatile synthons for other new pyridothienopyrimidines 12–15 as well as [1,2,4] triazolopyridothienopyrimidines 16–19.     

Studies with enaminones: The reaction of enaminones with aminoheterocycles. A route to azolopyrimidines,azolopyridines and quinolines

The enaminones 1b,d,f react with 4‐phenyl‐3‐methyl‐5‐pyrazoleamine 3a to yield the pyrazole derivatives 4a‐c that cyclised readily on reflux in pyridine solution in presence of hydrochloric acid to yield the pyrazolo[1,5‐a]pyrimidines 5a‐c. Similarly 3(5)‐amino‐1H‐triazole (3b) reacted with 1b,d,f to yield the triazolo[1,5‐a]pyrimidines 5d‐f. In contrast attempted condensation of the 5‐tetrazoloamine (3c) with 1a,d,e resulted in its trimerisation and only triaroylbenzene 8a,d,e was isolated. The reaction of 1a,b,d with anthranilonitrile 9a and the reaction of 1a‐c with the 2‐aminocyclohexene thiophene‐3‐nitrile 10a afforded the cis enaminones 11a‐c and 12a‐c. Similarly, reaction of 1a‐c with the methylanthranilate 9b and reaction of 1b,e with ethyl 2‐aminocyclohexene thiophene‐3‐carboxylate 10b afforded the cis enaminones 11d‐f and 12d,e respectively. Attempted cyclization of 11a‐c into quinoline failed. Successful cyclization of 11d into the quinolinone 13 could be affected, on heating for five minutes in a domestic microwave oven at full power. The reaction of 1a‐c,f with piperidine afforded the trans enaminones 14a‐d. Similarly, trans 14e was formed from the reaction of 1b with morpholine. The coupling reaction of 1b with excess of benzene diazonium chloride afforded the formazane 16. The enaminone 2 reacted with heterocyclic amines to yield the pyridones 17,18.     

4‐Toluenesulfonamide as a Building Block for Synthesis of Novel Triazepines,Pyrimidines, and Azoles

N‐{(E)‐(dimethylamino)methylidenearbamothioyl}‐4‐toluenesulfonamide ( 2 ) was obtained by reaction of N‐carbamothioyl‐4‐toluenesulfonamide ( 1 ) with dimethylformamide dimethylacetal or alternatively by the reaction of 1‐(dimethylamino)methylidenethiourea with tosyl chloride. Compound 2 was reacted with substituted anilines to yield anilinomethylidine derivatives 3a , 3b , 3c , 3d , 3e , 3f , 3g . Treatment of 3a , 3b , 3c , 3d , 3e , 3f , 3g with phenacyl bromide gave triazepines 4a , 4b , 4c , 4d , 4e , 4f , 4g and imidazoles 5a , 5b , 5c , 5d , 5e , 5f , 5g . Esterification of compound 3e afforded ester derivative 6 , which was subjected to react with hydrazine to yield hydrazide derivative 7 . Oxadiazole 8 was obtained by reaction of 7 with CS₂/KOH. Compound 3e was treated with o‐aminophenol or o‐aminothiophenol to give benzazoles 9a , 9b . N‐(Diaminomethylidene)‐4‐toluenesulfonamide ( 10 ) reacted with enaminones to yield pyrimidines 11 , 12 , 13 , respectively. The structures of the compounds were elucidated by elemental and spectral analyses. Some selected compounds were screened for their in vitro antifungal activity. In general, the newly synthesized compounds showed good antifungal activity.     

Phenacyl Bromides Revisited: Facile Synthesis of Some New Pyrazoles,Pyridazines, and Their Fused Derivatives

Phenacylmalononitriles 8a , 8b react with hydrazines under dry conditions to afford the pyrazole derivatives 9a , 9b , 9c , 9d and in refluxing dioxane to afford the pyrazolo[3,4‐c]pyridazine derivatives 11a , 11b , 11c , 11d and the pyridazine‐6‐imine derivatives 12a , 12b , 12c , 12d . Compounds 12a , 12b were transformed into their oxo analogs 13a , 13b upon reflux in ethanolic HCl, whereas 12c , 12d were transformed into the furan derivatives 14a , 14b under the same reaction conditions (reflux in ethanolic HCl). Compounds 8a , 8b could be transformed directly into the benzoyl‐pyrazole derivatives 16a , 16b , 16c , 16d upon coupling with diazotized aromatic amines in pyridine. The structures of the new compounds were substantiated by elemental analyses and spectral data as well as x‐ray crystallographic analysis. Plausible mechanisms for the unexpected transformations are suggested.     

Furopyridines. XIII. Reaction of 2-methylfuro[2,3-b]-, -[3,2-b]-, -[2,3-c]- and -[3,2-c]pyridines with lithium diisopropylamide

Lithiation of 2-methylfuro[2,3-b]- 1a , -[2,3-c]- 1c and -[3,2-c]pyridine 1d with lithium diisopropylamide at ?75° and subsequent treatment with deuterium chloride in deuterium oxide afforded 2-monodeuteriomethyl compounds 2a, 2c and 2d , while 2-methylfuro[3,2-b]pyridine 1b gave a mixture of 1b, 2b , 2-methyl-3-deuteriofuro[3,2-b]pyridine 2′b and 2-(1-proynyl)pyridin-3-ol 5 . The same reaction of 1a at ?40° gave 3-(1,2-propadienyl)pyridin-2-ol 3 and 3-(2-propynyl)pyridin-2-ol 4 . Reaction of the lithio intermediates from 1a, 1c and 1d with benzaldehyde, propionaldehyde and acetone afforded the corresponding alcohol derivatives 6a, 6c, 6d, 7a, 7c, 7d, 8a, 8c and 8d in excellent yield; while the reaction of lithio intermediate from 1b gave the expected alcohols 6b and 8b in lower yields accompanied by formation of 3-alkylated compounds 9, 11, 12 and compound 5 . While reaction of the intermediates from 1a, 1b and 1d with N,N-dimethylacetamide yielded the 2-acetonyl compounds 13a, 13b and 13d in good yield, the same reaction of 1c did not give any acetylated product but recovery of the starting compound almost quantitatively.     

Indolizines,triazolo[4,3‐a]pyridines,benzimidazo[1,2‐d]oxadiazoles,and pyrazolo[1,5‐c]triazoles via nitrogen and sulfur ylides

The pyridinium salts 2a,b reacted with dimethyl acetylenedicarboxylate (DMAD) to give the indolizine derivatives 6a,b . Pyridinium salts 2a,b also reacted with pyrazole‐5‐diazonium salt to afford the hydrazonoyl bromides 8a,b , which on treatment with aqueous ethanolic sodium carbonate furnished the 8aH‐1,2,4‐triazolo[4,3‐a]pyridine 10 . When sulfonium bromide 11 was treated with nitrous acid and with pyrazole‐5‐diazonium salt, it afforded the new hydroximoyl and hydrazonoyl halides 12 and 17 , respectively. Compound 12 reacted with 2‐methylthiobenzimidazole to furnish benzimidazo[1,2‐d]‐1,2,4‐oxadiazole derivative 14 . Treatment of either 12 with 3‐phenyl‐5‐aminopyrazole or 17 with triethylamine resulted in the formation of the same product: pyrazolo[1,5‐c]‐1,2,4‐triazole derivative 16 . © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:432–436, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20037     

Hetero-Diels-Alder cycloadditions of α,β-unsaturated acyl cyanides. Part 2. Reactions with N,N-dimethyluracils,a new route to 5-substituted uracil derivatives

The [4 + 2] cycloadditions of 2-oxobut-3-enenitrile ( 1a ), 2-oxopent-3-enenitrile ( 1b ), and ethyl 4-cyano-4-oxobut-2-enoate ( 1c ) with 1,3-dimethyluracil ( 2 ), 1,3, 6-trimethyluracil ( 9 ), or 1,3,5-trimethyluracil ( 16 ) were investigated. The reactions of 1a with 2 or with 9 lead to bicyclic adducts 3 and 10 , respectively. These hexahydro-cis-pyranopyrimidines undergo ring opening under acidic conditions, restoring in 4 and 11 , respectively, an uracil system comprising 2-hydroxybut-2-enenitrile as a side chain at C(5). The surprisingly stable enols tautomerize slowly to the corresponding acyl cyanides 6a and 13a , respectively. Reacting 1b or 1c with 2 and with 9 does not afford cycloadducts; instead the uracil derivatives 6b, c and 13b, c , respectively, show up, carrying at C(5) α-oxobutanenitrile side chains. Cleavage of the acyl cyanide functions in 6a–c and 13a–c with nucleophilic agents produces various acids, esters, or amides, i.e. derivatives 8a–c and 15–c , respectively. The methyl esters 8a (X ? MeO, R ? H) and 15a (X ? MeO, R ? H) are also formed directly from the adducts 3 and 10 , respectively, with acid or base catalysis in presence of MeOH. The cycloadducts 17a and 17c , resulting from the reaction of 1a and 1c with 16 , respectively, have a Me group at the ring junction C(4a) and are stable. The structure of 17c proves that this hetero-Diels-Alder addition of inverse electron demand follows the endo-mode.     

Furopyridines. IX. Syntheses and properties of 3-ethoxy derivatives of furo[2,3-b]-, furo[3,2-b]-, furo[2,3-c]- and furo[3,2-c]pyridine

Reaction of ethyl 3-ethoxycarbonylmethoxyfuropyridine-2-carboxylates 2a-2d with sodium ethoxide afforded 3-ethoxy derivatives 3a-3d which converted to 3-ethoxyfuropyridines 5a-5d by hydrolysis and decarboxylation of the ester group. Vilsmeier reaction of 5a and 5b gave 2-formyl-3-ethoxy derivatives 6a and 6b and 2-formyl-3-chloro derivatives 7a and 7b , while 5c and 5d did not give any formyl compound. Bromination of 3-ethoxyfuropyridines with 1 equivalent mole of bromine gave 2-bromo-3-ethoxyfuropyridines 9a-9d , whereas reaction with 3 equivalents of bromine yielded 2,2-dibromo-3,3-diethoxy-2,3-dihydrofuropyridines ( 10a and 10b ) and/or 2-bromo-3,3-diethoxy-2,3-dihydrofuropyridines 11b , 11c and 11d . Treatment of compounds 5a-5d with n-butyllithium in hexane-tetrahydrofuran at ?70° and subsequent addition of N,N-dimethylformamide yielded 2-formyl derivatives 6a-6d .     

[(1,3-Dioxolan-2-yliden)methyl]phosphonate und -phosphinate als (einfache) Synthone in der Heterocyclensynthese

[(1,3-Dioxolan-2-ylidene)methyl]phosphonates and -phosphinates as [simple] Synthons in Heterocyclic Synthesis The readily available [(1,3-dioxolane-2-ylidene)methyl]phosphonates and -phosphinates 2a–f (Scheme 1) can be transformed with amines to aliphatic ketene N,O-and N,N-acetales (see Scheme 2, 2a → 3–7 ). Alkanediamines yield with 2a–f the imidazolidines 8a–f and the hexahydropyrimidines 9a–d (Scheme 3). the oxazolidine derivatives 10a–e and the thiazolidine 11 are accessible under special reaction conditions starting from 2a, b (Scheme 4). Hydrazines react with the CN-group-containing ketene O,O-acetals 2a–c to the pyrazoles 12a–g , whereof 12a, d, e can be cyclized to pyrazolo[1,5-a]pyrimidines 13a–d (Scheme 5). Amidines as starting materials transform 2a–c in an analogous way to the pyrimidine derivatives 14a–c (Scheme 6).     

Green and Efficient Synthesis of 4‐Heteryl‐Quinolines and Their Antibacterial Evaluations

A green and efficient synthesis of 4‐heteryl‐quinolines ( 9a , 9b , 9c , 9d ), ( 10a , 10b , 10c , 10d ) and ( 11a , 11b , 11c , 11d ) has been described using PEG‐600 as a green solvent. Initially, 4‐chloro‐2‐methylquinolines ( 5a , 5b , 5c , 5d ) on reaction with aromatic heterocyclic thiols ( 6 ), ( 7 ), and ( 8 ) using PEG‐600 at 100°C for 30–40 min resulted in ( 9 ), ( 10 ), and ( 11 ) in good yields. Alternatively, ( 9 ), ( 10 ), and ( 11 ) could also be prepared in dimethylformamide using K2CO3 as base and tetrabutylammonium bromide as phase transfer catalyst at 100°C for 1–2 h. All the compounds were synthesized and characterized by IR, NMR, mass spectroscopy, and 13C NMR analysis. All synthesized compounds were screened for their antibacterial activity against clinical strains that include Gram‐positive (Bacillus subtilis MTCC 121, staphylococcus aureus MLS‐16 MTCC 2940, Micrococcus lutes MTCC 2470, and Staphylococcus aureus MTCC 96) and Gram‐negative bacteria (Candida albicans MTCC 3017, Klebsiella planticola MTCC 530, Escherichia coli MTCC 739, and Pseudomonas aeruginosa MTCC 2453). The results revealed that compounds ( 9a , 9d , 10a , 10c , 11b , and 11d ) exhibited significant antibacterial activity almost equal to the standard drug, that is, Ciprofloxacin.     

Pyrazoles and pyrazolo[4,3‐e]pyrrolo[1,2‐a]pyrazines II

Synthesis of the title compounds was achieved using the anils 2a , 2b , 2c , 2d , 2e and 5a , 5b , 5c derived from the 4‐aminopyrazole 1 as starting materials. These compounds were allowed to react with mercaptoacetic acid in boiling dry benzene to afford the corresponding thiazolidinones and spiro‐thiazolidinones 3a , 3b , 3c , 3d , 3e and 6a , 6b , 6c , respectively. Pictet—Spengler reaction of the 4‐aminopyrazole hydrochloride 7 with aromatic aldehydes and cyclic ketones resulted in the formation of new pyrazolo[4,3‐e]pyrrolo[1,2‐a]pyrazines 8a , 8b , 8c , 8d , 8e and 9a , 9b , respectively. Other derivatives of pyrazolo pyrrolopyrazines 10 and 11 were obtained via the reaction of the amino derivative 1 with 1,1′‐carbonyldiimidazol and CS₂, respectively. J. Heterocyclic Chem., (2011).     

Synthesis of Pyridotriazolopyrimidines as Antitumor Agents

2‐Hydrazino‐5,7‐di‐p‐tolylpyrido[2,3‐d ]pyrimidin‐4(3H )‐one ( 4 ) was prepared and condensed with different aldehydes 5a , 5b , 5c , 5d , 5e , 5f , 5g to give the corresponding hydrazone derivatives 6a , 6b , 6c , 6d , 6e , 6f , 6g . Oxidative cyclization of the latter compounds 6a , 6b , 6c , 6d , 6e , 6f , 6g gave the corresponding pyrido[2,3‐d ][1,2,4]triazolo[4,3‐a ]pyrimidin‐5(1H )‐ones 7a , 7b , 7c , 7d , 7e , 7f , 7g . Furthermore, compound 4 reacted with benzoyl chloride, triethyl orthoformate, acetyl chloride, ethyl chloroformate, and carbon disulphide in alcoholic KOH solution to afford the corresponding pyrido[2,3‐d ][1,2,4]triazolo[4,3‐a ]pyrimidinones ( 7a , 8 , 9 , 10 , 11 ). The reaction of thione 3 or its 2‐methylthio derivative 16 with hydrazonoyl halides 12a , 12b , 12c , 12d , 12e , 12f , 12g , 12h , 12i , 12j , 12k , 12l , 12m yielded the corresponding pyrido[2,3‐d ][1,2,4]triazolo[4,3‐a ]pyrimidinones 15a , 15b , 15c , 15d , 15e , 15f , 15g , 15h , 15i , 15j , 15k , 15l , 15m . The structures of all the products were confirmed by elemental and spectral analyses (¹H NMR, ¹³C NMR, IR, and MS). In addition, the anticancer activity of 20 pyridotriazolopyrimidinones against two cancer cell lines namely MCF‐7 and HepG2 was evaluated, and the results revealed that compounds 7d and 9 have promising activity , compared with doxorubicin, which used as standard reference drug.     

Synthesis and characterization of some new 4,4′‐(1,4‐phenylene)dipyrimidine and 6,6′‐(1,4‐phenylene)‐di(pyridin‐2(1H)‐one) derivatives

A series of new 4,4′‐(1,4‐phenylene)dipyrimidines 5a–c, 8a–c , and 10a,b have been synthesized from the reaction of amidines 1a–c with the dienaminone 2 , bis‐chalcone 6 , or ylidenemalono‐ nitrile 9 . The reaction of malononitrile and ethyl cyanoacetate with 2 gave 6,6′‐(1,4‐phenylene)di(pyridin‐2(1H)‐ones) ( 15a,b ). The structures of the products were proved by elemental analyses, IR, MS, ¹H, and ¹³C NMR spectroscopy. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:507–512, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20150     

Synthesis,Structural Characterization,and Biological Evaluation of Novel Substituted 1,3‐Thiazole Derivatives Containing Schiff Bases

In this study, thiazole derivatives containing Schiff bases ( 7a , 7b , 7c , 7d , 7e , 7f , 8a , 8b , 8c , 8d , 8e , 8f , 9a , 9b , 9c , 9d , 9e , 9f ) were synthesized in moderate to high yields (49–94%) using the Hantzsch reaction with thiosemicarbazone derivatives ( 5a , 5b , 5c ) and 2‐bromo‐1‐phenylethanone derivatives ( 6a , 6b , 6c , 6d , 6e , 6f ). The structures of synthesized compounds were elucidated by IR, ¹H NMR, ¹³C NMR, elemental analyses, mass spectroscopy and X‐ray diffraction analysis techniques. Moreover, the synthesized compounds were tested for their in vitro antifungal activity and most of them exhibited moderate to good activity against Fusariumoxysporumf.sp. lycopersici.      

Darstellung,Kristallstrukturen und Schwingungsspektren von [OsCl(acac)(EPh3)], E = P,As, Sb

Synthesis, Crystal Structures, and Vibrational Spectra of [OsCl(acac)(EPh₃)], E = P, As, Sb By reaction of tetrachloroacetylacetonatoosmate(IV) with PPh₃, AsPh₃ or SbPh₃ in ethanol the complexes [OsCl(acac)(EPh₃)], E = P, As, Sb are formed, which are purified by chromatography on silica gel. X-ray crystal structure determinations of the isotypic single crystals of [OsCl(acac)(EPh₃)] (monoclinic, space group P 2₁/c, Z = 4; E = P ( 1 ): a = 12.972(2), b = 18.255(2), c = 16.517(2) Å, β = 112.61(2)°; E = As ( 2 ): a = 13.173(5), b = 18.299(5), c = 16.429(5) Å, β = 112.346(5)°; E = Sb ( 3 ): a = 13.573(3), b = 18.520(3), c = 16.440(9) Å, β = 111.78(2)°) result in mean bond distances Os–P = 2.412, Os–As = 2.485, Os–Sb = 2.619, Os–Cl = 2.354 and Os–O = 2.032 Å. The IR spectra (10 K) exhibit the inner ligand vibrations of the acac and EPh₃ groups with nearly constant frequencies and the stretching vibrations of OsP at 500–524, of OsAs at 330–339, of OsSb at 271–278, of OsCl at 317–322 and of Os–O in the range 460–694 cm^–1.     

1,4-Benzoxazin-2-ones,benzo[d]oxazoles and 2H-1,4-benzoxazines from the reaction of 2-(methoxyimino)benzen-1-ones with arylacetates,arylacetic acids and trans- stilbene

10-(Methoxyimino)phenanthrene-9-one 1 reacts thermally with the arylacetic derivatives 2(a-j ) to yield the corresponding 1,4-benzoxazin-2-ones 4(a-d,f ) and benzo[d]oxazoles 5(a-e,g ). Similarly, reaction of the monoximes 7a, 7b with compounds 2a, 2d respectively affords 8a, 8b , while action of trans-stilbene on the monoximes 1, 7a, 7b leads to the 1,4-benzoxazines 10, 11, 13 , obtained along with the corresponding 2-phenyloxazoles 5a, 8a, 8c and compound 12 .     

Photochemische Cycloadditionen von 3-Phenyl-2H-azirinen an Carbonsäurechloride. 35. Mitteilung über Photoreaktionen

Irradiation of 2, 3-diphenyl-2H-azirine ( 1a ) and 1-azido-1-phenyl-propene, the precursor of 2-methyl-3-phenyl-2H-azirine ( 1b ), in benzene, with a high pressure mercury lamp (pyrex filter) in the presence of acid chlorides yields the oxazoles 5a–d (Scheme 2). Photolysis of 2, 2-dimethyl-3-phenyl-2H-azirine ( 1c ) under the same conditions gives after methanolysis the 5-methoxy-2, 2-dimethyl-4-phenyl-3-oxazolines 7a, b, d , while hydrolysis of the reaction mixture leads to the formation of the 1, 2-diketones 8a, c, d (Scheme 4). The suggested reaction path for all these reactions is a 1, 3-dipolar cycloaddition of the photochemically generated benzonitrilemethylides 2 to the carbonyl double bond of the acid chlorides to give the intermediates 4 , followed by either elimination of hydrogen chloride or solvolysis (Schemes 2 and 4). Irradiation of 1c in the presence of acetic acid anhydride leads via the intermediate 9 to the 5-hydroxy-3-oxazoline 10 and the 5-methylidene-3-oxazoline 11 (Scheme 5).