Synthese von β-Nitroalkenyl-benzylphosphorylderivaten

Synthesis of β-Nitroalkenyl-benzylphosphorylderivatives Starting from methoxy-chlormethylbenzaldehydes 2 the benzylphosphonates and -phosphinoxides 3 A, B had been synthesized, which could be transformed via the Schiff-bases 4 A, B to phosphorylated nitrostyrenes 5 A, B and nitropropenylbenzenederivatives 6 A, B . The phosphonoacids 3 Ad, 3 Bd and 6 Ba could be prepared from the corresponding esters by direct acidic hydrolysis or by dealkylation with trimethylsilylbromide and hydrolysis of the trimethylsilylesters respectively.     

Synthese und Reaktionen von β-Campholenverbindungen

Synthesis and Reactions of β-Campholene Compounds In contrast to the well known α-campholenic ( B ) and fencholenic compounds ( C ) little is known about β-campholenic derivatives ( A ) because of their difficult accessibilitiy. β-Campholenic compounds ( A ) can be obtained: (1) by Baeyer-Villiger oxidation of camphor via lactone 7 and β-dihydrocampholenic lactone ( 5 ); (2) by Beckmann fragmentation of camphor oxime via α-( 2 ) and β-campholenic nitril ( 3 ) and the lactone 5 ; and ( 3 ) by acid catalysed rearrangement of α-campholenic derivatives ( B , 17a , b ). The β-analogous brahmanol ( 14 ) can be synthesized by the reaction of the β-campholenic bromide ( 11 ) with methyl diethyl malonate or by rearrangement of brahmanol.     

Zur Chemie aktivierter Vinylhalogenide. Synthese und Reaktionsverhalten von 3-(β-Chlor-vinyl)-acrylnitrilen

Chemistry of Activated Vinyl Halogenides. Synthesis and Reaction Behaviour of 3-(β-Chlorovinyl)acrylonitriles Formamide chlorides 2 react with arylmethylketones 8 to give arylsubstituted β-chloro-vinyl-methinimmonium salts 4 which were converted by reaction with cyanoacetic acid derivatives 9 to 3-(β-chlorovinyl)acrylonitriles 7 . These nitriles react with various nucleophiles, such as aliphatic and aromatic amines, sodium sulfide, sodium thiosulfate, ammonium dithiocarbamates or alkali hydroxide to yield 3-(β-aminovinyl)acrylonitriles 10 or 19 , substituted 3-(β-hydroxyvinyl)acrylonitriles 14 , substituted 3-(β-mercaptovinyl)acrylonitriles 24 , 1,2-dihydro-2-imino-pyridines 12 , 2-amino-pyridinium salts 13 , 2-amino-pyrylium salts 15 , 2-pyridones 17 , 2-imino-2H-thiopyranes 26 , and 2-amino-thiopyrylium salts 18 , respectively. From the experimental results it was confirmed that the nitriles 7 have an ambident reactivity which can be interpreted theoretically on the basis of a simple HMO method. Some chemical reactions as well as u.v., i.r. and n.m.r. spectroscopical data confirm the structure of the reported compounds.     

Photochemie von Aminoketonen. IV [1]. Synthese von 3-Aryl-pyrrolidinolen-(3) durch Photocyclisierung von β-Amino-propiophenonen

Photochemistry of Aminoketones. IV. Synthesis of 3-Aryl-pyrrolidinols-(3) via Photocyclization of β-Amino-propiophenones Photolysis (λ_irr ≥ 300 nm) of N-benzyl-N-benzoyl-β-aminopropiophenones 6–9 in abs. ether affords a 47–50% yield of N-benzoyl-pyrrolidinols 12–18 . The relative configurations of the diastereomeric 12–18 are determined by ¹H-n.m.r. spectroscopy. The different behaviour of the N-acylated 6–9 in contrast to N,N-dialkyl-β-aminopropiophenones is explained by assumption of a dipol-dipol interaction between the keto and the amido carbonylgroups in the n,π*-excited state.     

Reaktionen von β-Chlorvinylaldehyden. V [1]. Zur Bildung von 2,2′-Thiopyrylotrimethinfarbsalzen aus 2-(α-Formylalkyliden)-2H-thiopyranen

Reactions of β-Chlorovinylaldehydes. V. The Formation of 2,2′-Thiopyrylocyanine Dyes from 2-(α-Formylalkylidene)-2H-thipyranes Substituted β-chlorocrotonaldehydes react with Na₂S · 9H₂O to form 2-(α-formyl-alkylidene)-2H-thiopyranes 1 . The corresponding thiopyrylium salts 2 which are easily available from 1 and strong acids exist in the enolic form (2-β-hydroxyvinyl-thiopyrylium salts). They are converted at room temperature in methanol solution to dark green compounds, which are identified as 2,2′-thiopyrylotrimethincyanine dyes 3 . The mechanism of formation of compounds 3 is discussed.     

r-5-(α-Halogenbenzyl)-3, t-4-diaryl-c-4-hydroxy-oxazolidin-2-one als Ringtautomere von α-(Arylaminocarbonyloxy)-β-halogen-dihydrochalkonen

r-5-(α-Halogenobenzyl)-3, t-4-diaryl-c-4-hydroxy-oxazolidin-2-ones as Ring Tautomers of α-(N-Arylaminocarbonyloxy)-β-halogeno-dihydrochalcones The reaction of chalcone halogenohydrins ( 1–3 ) with arylisocyanates does not stop at the stage of the α-arylaminocarbonyloxy-β-halogeno-dihydrochalcones ( 7 ), but the cyclic urethanes 4–6 are formed. Compound 7h was synthesized independently. The structure and stereochemistry of 4–6 and 7h were determined by ¹³C n.m.r. spectroscopy.     

Die Reaktion von α,β-Dihalogen-propionitrilen mit monosubstituierten Hydrazinen - einfache Synthese 1-substituierter 3- bzw. 5-Amino-pyrazole

The Reaction of α,β-Dihalogeno-propionitriles with Monosubstituted Hydrazines — A Simple Synthesis of 1-Substituted 3- or 5-Amino-pyrazoles In methanol hydrazines 3 , and α,β-dihalogeno-propionitriles 1, 2 even at 0°C irreversibly yield 3 · HX, and α-halogenoacrylonitriles 4, 5 (A₁). Fast addition of alkyl- and aralkyl- hydrazines 3 to 4, 5 (C) gives 1-substituted 1-(2′-halogeno-2′-cyan-ethyl)-hydrazines 6 , the addition of arylhydrazines 3 to 4, 5 (D) 1-aryl-2-(2′-halogeno-2′-cyan-ethyl)-hydrazines 8 . In methanol 6 spontaneously cyclise (E) to hydrogen halides 7 · HX of 1-alkyl- and 1-aralkyl-3-amino-pyrazoles, 8 with 2 moles of acids (F) to salts 10 · 2HY of 1-aryl-4-halogeno-5-imino-pyrazolidines, and the free 10 spontaneously (G) to hydrogen halides 9 · HX of 1-aryl-5-amino-pyrazoles. Mechanisms (A₁), (C), (D), (E), (F), and (G) are proved by t.l.c., ¹H-n.m.r., and isolation of intermediates, the structures of 7 resp. 9 , using the significant ¹H-n.m.r.-parameter Δ. Simple general syntheses are described for 3-amino-pyrazoles 7 (R = H, alkyl, aralkyl) or 5-amino-pyrazoles 9 (R = aryl) starting with α,β-dihalogeno-propionitriles 1, 2 , and for α-bromo-acrylonitrile 5 .     

Intermediates of Prostanoid Synthesis. Stereospecific conversion of (+)-5β-hydroxycyclopenten-2-yl-1β-acetic acid γ-lactone into (+)-1β-methoxycarbonylmethyl-2β,3β-(p-nitrobenzylidene)-dioxycyclopentan-5-one

Starting from (+)-5β-hydroxycyclopenten-2-yl-1β-acetic acid γ-lactone ( 1 ), (+)-1β-methoxycarbonylmethyl-2β, 3β-(p-nitrobenzylidene)-dioxycyclopentan-5-one ( 7 ) was prepared within 4 steps. Subsequent cleavage of the latter gives (−)-3β-hydroxy-1-methoxy-carbonylmethylcyclopent-1-en-5-one ( 8a ). Hydroxylation of the lactone ( 1 ) was found to give (+)-2β,3β,5β-trihydroxycyclopentyl-1β-acetic acid γ-lactone ( 2a ) with cis-oriented hydroxy groups in respect to the lactone ring. No formation of the trans-isomer, as has been reported earlier [4], was observed.     

Synthese von ω-Acetyl-α-methylenpolyencarbonsäureestern

Synthesis of ω-Acetyl-α-methylenpolyene Carboxylic Esters The α-methylenpolyene carboxylic acids 1 and 2 are highly active against Gram-positive bacteria. If this activity arises from an interference with the cell membranes, then an abrupt change in biological properties is to be expected with growing chain length of simple model compounds. To make these tests possible, we describe here the synthesis of a series of homologue esters of type 40 . Their synthesis was achieved by Wittig reactions of polyene αω-dialdehydes 6 with acetyl-methylentriphenylphosphoran 5a and the protected carboxy-methylmethylen triphenylphosphonium salt 8 .