Untersuchungen über N-Methoxyguanidin 2. Umsetzungen mit Chlordithioameisensäureethylester und mit Kohlenstoffdisulfid,Acetylierungsreaktionen [1]

Studies on N-Methoxyguanidine. 2. Reactions with the Ethylester of Chlorodithioformic Acid and with Carbon Disulfide, Acetylation Reactions The reaction of N-methoxyguanidine with the ethylester of chlorodithioformic acid yields the known 3-amino-5-ethylthio-1,2,4-thiadiazole. With carbon disulfide no reaction occurs. N-Methoxyguanidine reacts with acetic anhydride – dependent on reaction conditions – to form mono-, di- or triacetyl-N-methoxyguanidines. The properties of these hitherto not known compounds are described, mass spectra are given.     

Über Chalkogenolate. 196. Untersuchungen über N-(Methoxycarbimidoyl)guanidin 2. Umsetzungen mit Chlordithioameisensäureestern

On Chalcogenolates. 196. Studies on N-(Methoxycarbimidoyl)guanidine. 2. Reactions with Esters of Chlorodithioformic Acid N-(Methoxycarbimidoyl)guanidine reacts with esters of chlorodithioformic acid to produce the hitherto not known esters of N-(Methoxycarbimidoyl)guanidinedithiocarbonic acid (MCGT-R; formula see ?Inhaltsübersicht”?). By-product is the corresponding 2-amino-4-methoxy-6-alky(aryl)thio-1,3,5-triazine. MCGT-R, where R = CH₃, C₂H₅, C₆H₅, have been characterized by means of electron absorption, infrared, nuclear magnetic resonance, and mass spectra. The spectra and the related tautomeric structures of the dithioesters are discussed.     

Notiz über mikrobiologische Umsetzungen mit Halobacterium halobium: Reduktion von 3-Oxobutansäure-ethylester und Hydrolyse von 3-Hydroxybutansäure-ethylester. Cooperative Effekte von Reduktase und Hydrolase

Note on Biotransformations with Halobacterium halobium: Reduction of Ethyl 3-Oxobutanoate and Hydrolysis of Ethyl 3-Hydroxybutanoate. Cooperative Effects of Reductase and Hydrolase The archaebacterium Halobacterium halobium, growing in saturated NaCl solution, is tested for its ability to achieve biotransformations. We found that this microorganism does accept only a small variety of compounds as substrates. Ethyl acetoacetate ( 1 ) is reduced to ethyl (S)-3-hydroxybutanoate ( 2 ) of optical purity of 40–76%, but in low chemical yields. The reduction is accompanied by hydrolysis of the hydroxy-ester to 3-hydroxybutanoic acid ( 3 ). Hydrolysis of rac-ester 2 by Halobacterium halobium gives (R)- 2 of optical purity of up to 88%, depending upon reaction time, together with the almost racemic hydroxy-acid 3 , both in low chemical yields. Hopes that the ‘extremist’ Halobacterium halobium would be able to effect unique conversions were not fulfilled.     

Über Umsetzungen von weißem Phosphor mit Metallorganylen

Reactions of White Phosphorus with Lithium Alkyls The reaction of white phosphorus with Lime (me = CH₃) (molar ratio P₄: Lime = 1:1) in DME or THF via insoluble lithium polyphosphides yields Li₃P₇ 1 , Li₂P₇me 2 and LiP₇me₂ 3 , which react with me₃SiCl or meBr to form P₇(Sime₃)₃, P₇(Sime₃)₂me and P₇me₃, respectively. All of these compounds were characterized by ³¹P-n.m.r. By higher amounts of Lime (molar ratio P₄:Lime = 1:2) Li₂P₇me is decomposed. The analogous reaction of P₄ with LiCme₃ yields Li₃P₇, LiP₇(Cme₃)₂, Li₂P₇Cme₃, and additionally LiP₄(Cme₃)₃ and LiP₃(Cme₃)₂. Again insoluble lithium polyphosphides were observed as intermediates. Addition of me₃SiCl to the reaction mixture affords P₇(Sime₃)₃, P₇(Sime₃)₂(Cme₃), P₇(Sime₃)(Cme₃)₂ P₄(Sime₃)(Cme₃)₃, and P₃(Sime₃)(Cme₃)₂. In n-hexane/THF the reaction of P₄ with LiCme₃ in the molar ratio of 1:2 predominantly yields the fourmembered ring LiP₄(Cme₃)₃ besides some of the three-membered ring LiP₃(Cme₃)₂, which with me₃SiCl yield P₄(Sime₃)(Cme₃)₃ and P₃(Sime₃)(Cme₃)₂. In addition to the mentioned main products are found: all compounds of the group P₈(Sime₃)₅(Cme₃) to P₈(Sime₃)(Cme₃)₅, the five-membered rings P₅(Sime₃)₂(Cme₃)₃ and P₅(Sime₃)₃(Cme₃)₂ as well as P(Sime₃)₂Cme₃ and P(Sime₃)₃.     

Beiträge zur Chemie der Silicium-Stickstoff-Verbindungen. 163. Untersuchungen über einige Verbindungen mit BNSi-Struktureinheiten

Chemistry of Silicon-Nitrogen Compounds. 163. Investigation of Some Compounds with BNSi Structure Fragments Some formerly unknown compounds with BNSi structure fragments were prepared (or obtained on a not expected way), confirmed in their structure and described in their properties: (EtO)₂BN(SiMe₃)₂ ( V ), FB[N(SiCl₃)₂]₂ ( XIII ), the derivatives IV, XVI – XIX of the six-, five- and four-membered ring systems cyclotriazatriborane, cyclodisilaboradiazane, and cyclosilaboradiazane and XXIII of a [3, 4]-spiro system. Br₂BN(SiMe₃)₂ ( III ), already known, was prepared by a different method.     

Über Oxocuprate. XVIII. Zur Kenntnis von Sr2CuO2Br2 mit einem Beitrag über La2NiO4

About Oxocuprates. XVIII. On Sr₂CuO₂Br₂ and a Contribution about La₂NiO₄ Sr₂CuO₂Br₂ (A) and La₂NiO₄ (B) were prepared and investigated by single crystal X-ray technique. (A) is isotypic with Sr₂CuO₂Cl₂, (B) with K₂NiF₄. Both compounds crystallize in the space group D–I4/mmm with the lattice constants (A): a = 399.1, c = 1 713.6 pm, (B): a = 387.6, c = 1 268.3 pm. A discussion about the octahedral distortion of Cu²⁺ and Ni²⁺ respectively in respect to other isotypic compounds is given.     

Photoinduzierte Reaktionen von 3-Phenyl-2H-azirinen mit Carbonsäureestern 40. Mitteilung über Photoreaktionen

Irradiation (280–350 nm light) of a benzene solution of 3-phenyl-2H-azirines 1a – e in the presence of carboxylate esters, whose carbonyl groups are activated by electron withdrawing groups situated in the acyl or alkyl moiety, produces 5-alkoxy-3-oxazolines (Tab. 1 and 4, Scheme 2) isolated in 18–82% yield. These heterocycles undoubtedly originate by regiospecific addition of the ester carbonyl group to the azirine-derived benzonitrile-methylide ‘dipole’ (Scheme 1). The 5-(2,′ 2′, 2′-trifluoroethoxy)-3-oxazolines, derived from 2′, 2′, 2′-trifluoroethyl carboxylic esters, on treatment with methanolic hydrogen chloride at low concentration, are smoothly transformed into the corresponding 5-methoxy-3-oxazolines (e.g. 16 → 17 , Tab. 5). Utilizing this process, various hitherto relatively unknown 9. 5-alkoxy-3-oxazolines become accessible. The constitution of the adducts is based essentially on spectral data. The structure of trans-5-methoxy-2,4-diphenyl-5-trifluoromethyl-3-oxazoline (trans- 14 ), the addition product of methyl trifluoroacetate and the benzonitrile-benzylide from 2,3-diphenyl-2H-azirine ( 1d ), was determined by X-ray crystallography (Section 5). Benzonitrile-isopropylide ( 22 ), resulting from the photochemical transformation of 2,2-dimethyl-3-phenyl-2H-azirine ( 1a ), also reacts with S-methyl thiobenzoate to give 2,2-dimethyl-5-methylthio-4,5-diphenyl-3-oxazoline ( 26 ). Ethyl cyanoacetate protonates predominantly the dipolar species derived from 1a at the nitrile C-atom and yields after work-up ethyl α-cyano-cinnamate ( 29 ) and ethyl isopropylidene-cyanoacetate ( 30 ) (Scheme 4). The relative rate of addition (k_rel) of benzonitrile-isopropylide ( 22 ) to methyl α-haloacetates and dimethyl oxalate was determined by competition experiments (Section 6). Log k_rel correlated satisfactorily (r = 0.97) with the pK_a of the acide derived from the ester reactant: log k_rel = ? 1.72 pK_a + 2.58 or with Taft's substituent constants σ*: log k_rel = 2.06 σ* ? 4.11 [k_rel(methyl dichloroacetate) = 1; Section 7.1]. On the basis of the results obtained, the mode of reaction of the so-called benzonitrile-methylide ‘dipole’ is discussed and a model for the transition state of addition of ester-carbonyl groups is proposed that accounts for the observed regiospecifity and steroselectivity.     

Über Chalkogenolate. 165. Umsetzungen von Hydrazin mit Kohlenstoffdisulfid. 4. Salze des S-Methylesters der N-Dithiomethylendithiocarbazidsäure

On Chalcogenolates. 165. Reactions of Hydrazine with Carbon Disulfide. 4. Salts of the S-Methyl Ester of N-Dithiomethylene-dithiocarbazic Acid The S-methyl ester of dithiocarbazic acid reacts with carbon disulfide in the presence of sodium or potassium hydride at ?15°C to yield the hitherto unknown salts of the S-methyl ester of N-dithiomethylene-dithiocarbazic acid. The prepared compounds , have been studied with chemical methods as well as with electron absorption, infrared, nuclear magnetic resonance (¹H and ¹³C), and mass spectra.