α-Alkylmercapto- und α-Arylmercapto-alkylisocyanate

α-Alkylmercapto- and α-Arylmercapto-alkylisocyanates α-Alkylmercapto- and α-arylmercapto-alkylisocyanates 2 were prepared from α-halosulfides 1 by reaction with silver cyanate. With ammonia, primary or secondary amines they give the corresponding α-mercaptoalkyl-ureas 4 ; with alcohols, the α-mercaptoalkylurethans 3.     

Synthese von γ,γ'-Dihydroxysulfonen und γ-Hydroxy-γ'-ketosulfonen

Syntheses of γ,γ'-Dihydroxysulfones and γ-Hydroxy-γ'-ketosulfones Reduction of γ,γ'-diketosulfones 1 with dimethylaminoborane leads to γ,γ'-dihydroxysulfones 3 via γ-hydroxy-γ'-ketosulfones 2 . The influence of substituents on the ratio of the yields of 2 and 3 is investigated.     

Dithio- und Thionester, 57. Mitt.: Synthese N-geschützter β- und γ-Aminosäuredithioester und -thionester

Dithio and Thiono Esters, LVII: Synthesis of Dithio and Thiono Esters of N-Protected β- and γ-Amino Acids The N-Protected β-aminonitriles 1 were transformed into the imidoester or thiolimidoester hydrochlorides 2 or 3 according to Pinner and sulfhydrolyzed with H₂S to give the N-protected β-amino thiono esters 4 or dithio esters 5 . Alkylation of the amides 6 and thioamides 7 yields the iminium salts 8/9 and their sulfhydrolysis again 4/5 . By the first approach N-protected γ-amino nitriles 11 were converted into the γ-amino thiono esters 14 and dithio esters 15 .     

Neue Reaktionen an Phthalidisochinolinalkaloiden. Alkoxytauschreaktionen und Isomerisierungen an α- und β-Narcotin

New Reactions of Phthalidoisoquinoline Alkaloids. Alkoxy Exchange Reactions and Isomerisations of α- and β-Narcotine Substitution of the 7-methoxy group in α- and β-narcotine by other alkoxy groups occurs in an anhydrous ROH/RONa system. It is accompanied by isomerisation in position 3 with preference for the α-configuration (5R, 3S). In an alkaline aqueous system (ROH/KOH or 1N KOH only isomerisation in position 3 with preference for the β-configuration (5R, 3R) was observed. Some of the new 7-alkoxynarcotines were evaluated for their antitussive activity.     

Über β-Chlor- und β-Mesyl-äthylhydrazine

β-Chloro- and β-Mesylethyl Hydrazines From benzaldehyde-β-hydroxyethyl-hydrazone hydrochloride ( 6 ) with thionyl chloride the benzaldehyde-β-chloroethyl-hydrazone hydrochloride ( 7 ) is formed. This gives upon hydrolysis with dilute hydrochloric acid the β-chloroethyl-hydrazine dihydrochloride ( 5 ). – Methylhydrazine and 1,2-dichloroethane undergo reaction at room temperature to methylhydrazine hydrochloride ( 10 ) and N-methyl-N-β-chloroethyl-hydrazine ( 9 ), which can be isolated as dihydrochloride 12 . – Benzaldehyde-β-hydroxyethyl-hydrazone ( 6 ) forms with mesyl chloride the benzaldehyde-(N-methylsulfonyl)-N-β-mesylethyl-hydrazone ( 14a ) which can be hydrolyzed with dilute hydrochloric acid to the N-β-mesylethyl-methanesulfonic hydrazide ( 15 ).     

Analysis of γβ, βγ, γγ, ββ multiple turns in proteins

Abstract: The number of γ‐turns in a representative protein dataset selected from the current Protein Data Bank has increased almost seven times during the past decade. Eighty percent classic γ‐turns and 57% inverse γ‐turns are associated as multiple turns with either another γ‐turn or a β‐turn. We refer to these as multiple turns of the (γβ)_1,2,3 or (βγ)_1,2,3 type, depending upon whether the γ‐turn is before or after the β‐turn along the protein chain, respectively. However, for multiple turns involving only γ‐turns, we follow the nomenclature analogous to that proposed earlier for the multiple (or double) β‐turns. Fifty‐eight per cent β‐turns are associated as multiple turns with another β‐turn. We extracted multiple turns from the protein dataset and classified them on the basis of individual γ‐ or β‐turn types and the number of overlapping residues. Furthermore, we evaluated the amino acid positional potentials and determined the statistically significant amino acid preferences, hydrogen bond/side‐chain interaction preferences in the multiple turns and secondary structure preferences for residues immediately flanking these turns. The results of our analysis would be useful in the modeling, prediction or design of multiple turns in proteins. The amino acid sequence corresponding to the multiple turn, position in the protein chain, PDB Code/chain in which multiple turn is present and the individual turn types constituting the multiple turns are available from our website and this information would also be integrated in our Database of Structural Motifs in Proteins ( http://www.cdfd.org.in/dsmp.html ).     

Thion- und Dithioester, 48. Mitt. α,β-Ungesättigte Thioester in Diels-Alder-Reaktionen und Michael-Additionen

Thiono and Dithio Esters, XLVIII: α,β-Unsaturated Thio Esters in Diels-Alder Reactions and Michael Additions The reaction of cinnamic acid thio esters with different dienophiles leads to the formation of the Diels-Alder products 3 – 8 ; with lithium enolates the Michael adducts 11 and 13 were isolated.     

Analysis of γβ, βγ, γγ, ββ continuous turns in proteins

Abstract: We report the observation of continuous turns in proteins which comprise individual γ‐turns or β‐turns or both that are situated immediately one after the other along the polypeptide chain. The continuous turns were identified from a representative data set of three‐dimensional protein crystal structures. The γβ/βγ, γγ and ββ continuous turns represent peptides of varying amino acid residue lengths and conformations. The continuous turns frequently observed in proteins were: γβ, between a coil and a strand; βγ, between a helix and a strand; γγ, between coils; and ββ, either between a strand and a coil or between strands or coils. We determined the statistically significant amino acid residue preferences at individual positions in the turn, calculated amino acid positional potentials and analyzed main chain hydrogen bonds and side‐chain interactions likely to stabilize the continuous turns. The data on continuous turns have been integrated in the database of structural motifs in proteins (DSMP) on our web server at ( http://www.cdfd.org.in/dsmp.html ). This is useful to make queries on sequences compatible with different continuous turns.     

α-Thiotetronsäuren, 1. Mitt.: Synthese und Eigenschaften von γ-Alkyliden-α-thiotetronsäuren

α-Thiotetronic Acids, I: Synthesis and Properties of γ-Alkylidene α-Thiotetronic Acids We report on the synthesis of the alkylidene α-thiotetronic acids 11 and 12a and a variety of their derivatives, starting with 2,3-dimethoxysuccinic thioanhydride ( 4 ) or diethyl 3-thioxoglutarate. The rhodium(II)-catalysed decomposition of the diazoketone 26 furnishes the reductone 12p and the aminoreductone 12r with the thietanone 27 as one of the by-products.     

Über Dialkyl-[β,β,β-trichlor-bzw. β,β,β-triphenyl-äthyl]-amine. 34. Mitt. über α-halogenierte Amine

Dialkyl-[β,β,β-trichloro- or β,β,β-triphenyl-ethyl]-amines Reactions of α-halo amines 2 with trichloromethyllithium give dialkyl-[β,β,β-triphenyl-ethyl]-amines 1 , with triphenylmethyllithium dialkyl-[β,β,β-triphenyl-ethyl]-amines 3 .     

Massenspektrometrische Untersuchungen an isomeren α,β- und β, γ-ungesättigten Ketonen mit raumerfüllenden Substituenten

A Mass Spectrometric Study on Isomeric α,β- and β,γ-Unsaturated Ketones with Bulky Substituents The mass spectra of the α,β- and β,γ-unsaturated ketones 1-4 (scheme 1) are very different depending on the stereochemistry of the double bond. The E-configurated ketone 2 predominantly shows McLafferty fragmentation, whereas Z-configurated ketone 1 reveals ?-cleavage. In the β, γ-unsaturated ketones 3 and 4, mainly loss of the pertinent allyl radical by α-cleavage was observed.     

N-Glykoside und Glykamine von Cyclopentylamin, 1.2.3.4-Tetrahydro-1-naphthylamin und 5α-Cholestan-3β-amin

N-Glycosides and Glycamines of Cyclopentylamine, 1,2,3,4-Tetrahydro-1-naphthylamine and 5α-Cholestan-3β-amine The galactosyl-, mannosyl- and lactosyl-N-glycosides of cyclopentylamine and the galactosyl- and glucosyl-N-glycosides of the other two title compounds are described. All N-glycosides are reduced by cyanoborohydride to the corresponding glycamines.     

Struktur-Wirkungs-Beziehungen bei Histaminanaloga, 23. Mitt. Absolute Konfiguration und histaminartige Wirkung der enantiomeren α-Chlormethylhistamine und Nα-Methyl-α-chlormethylhistamine

Structure-Activity Relationships of Histamine Analogues, XXIII: Absolute Configuration and Histamine-like Activity of the Enantiomeric α-Chloromethylhistamines and Nα-Methyl-α-chloromethylhistamines The histamine-like activities of the enantiomeric α-chloromethylhistamines (+)- 2a and (?)- 2a and of the Nα-methyl-α-chloromethylhistamines (+)- 2b and (?)- 2b on the guinea pig ileum (H₁) and atrium (H₂) are reported. The absolute configurations of the enantiomers were determined.     

α-Aminoalkylierungsreaktionen mit N-funktionellen Glyoxylsäurederivaten 5. Mitt.: α-Aminosäuren und Derivate

Aminoalkylation with Glyoxylic Acid Derivatives O.N- and N.N-Acetals as well as dialkylimoniumsalts of glyoxylic acid derivatives can be used for aminoalkylation of C-H-acid compounds, producing amides or esters of N.N-dialkylated α-aminoacids. The reaction is investigated on various examples.     

Herstellung und Eigenschaften von β-Ketopropansultonen und -sultamen

Synthesis and Properties of p-Oxopropanesultones and -sultames The 1,2-oxathiolan-4-one 2,2-dioxides 5 and the isothiazolidin-4-one 1,1-dioxides 6 were prepared by ester condensation. All compounds show pK_a, values around 4. The stability against alkali, especially of the sultones 5, is remarkable.     

β-Substituierte Enamine, 11. Mitt. Kondensationsprodukte aus γ-Chloracetessigester und primären aromatischen oder heteroaromatischen Aminen

β-Substituted Enamines, XI. Condensation Products from Reactions of γ-Chloroacetoacetic Ester with Primary Aromatic and Heteroaromatic Amines γ-Chloroacetoacetic ester ( 1a ) reacts with aniline via an α-(chloromethyl)enamine 2a to yield 4-anilino-5H-furan-2-one ( 4 ). It undergoes condensation reactions with heterocycles having primary aminogroups in position 2, e. g. 2-aminopyridine ( 6 ). 2-aminothiazole ( 9 ), 2-aminobenzimidazole ( 10 ), 2-aminobenzothiazole ( 11 ). Products are the fused chloromethylpyrimidones 8, 12, 13 and 14 .