bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective Synthesis of Polyamine Derivatives: Efficient derivatization of the secondary amino group of N‐monosubstituted 1,3‐diamines
Authors: Jentgens Christian , Hofmann Richard , Guggisberg Armin , Bienz Stefan , Hesse Manfred 
Published: December 2004

AbstractN‐Monosubstituted 1,3‐diamines were selectively functionalized at the secondary N‐atom via 2‐Ph‐substituted hexahydropyrimidine intermediates. Reaction of the diamines with benzaldehyde, followed by treatment with an electrophile and hydrolysis, provided the desired products with excellent selectivity and in high yields. N4,N9‐bis[3‐phenylprop‐2‐enoyl]spermine (4a), which was further converted to N1,N1 2‐bis[3‐phenylprop‐2‐enoyl]spermine (15) by a transamidation reaction, was prepared by this way in 82% yield from spermine (1). Compound 4a was alternatively synthesized in 83% yield, equally from 1, by a sequence involving intermediary protection of the terminal amino groups.
Structure‐Activity Relations for Imidazo‐pyridine‐Type Inhibitors of β‐D‐Glucosidases
Authors: Granier Thierry , Panday Narendra , Vasella Andrea 
Published: December 2004

AbstractThe triazole 7 and the known gluco‐ and manno‐configurated imidazoles 10 and 11 have been prepared by annulation of the azole ring to the aldonothiolactam 14 in a Hg(OAc)2‐promoted reaction with either hydrazine‐carbaldehyde or aminoacetaldehyde dimethyl acetal. Depending upon the reaction conditions, the synthesis of the imidazoles yielded mostly the gluco‐imidazole 19 or a mixture of the gluco/manno epimers 19/20. In contrast to the triazole 4, the isomeric triazole 7 proved a good inhibitor of retaining β‐glucosidases from sweet almonds and from Caldocellum saccharolyticum. This observation and the qualitative correlation between basicity and inhibitory power of the tetrahydropyridoazoles provide further evidence for the hypothesis of the ‘lateral protonation’ of glycosides by (some) retaining β‐glucosidases.
Oligosaccharide Analogues of Polysaccharides. Part 12. Synthesis of ‘acetyleno‐saccharide’‐derived cyclodextrin analogues
Authors: Bürli Roland , Vasella Andrea 
Published: December 2004

Abstract‘Acetyleno‐oligosaccharides’ in which two terminal ethynyl substituents enclose an angle (significantly) below 180° are building blocks for the preparation of cyclodextrin analogues. This is illustrated by the preparation of a cyclotrimer and a cyclotetramer; the C3‐symmetrical cyclotrimer 18 (Scheme 1) was synthesized in 13 steps (7.7%) and the C4‐symmetrical cyclotetramer 51 (Scheme 3) in 14 steps (4.3%) from the known dialkyne 21. The solubilities of 18 and 51 in H2O were determined by gravimetry; a saturated solution is 130 mM in the trimer 18 and 12.8 mM in the tetramer 51. The dependence of the optical rotation of 18 and 51 in H2O on the concentration, and the concentration dependence of the 1H‐NMR chemical shift of the signals of the 1CH groups of 51 (D2O) suggest that there is no significant self‐association of 18 and 51.
Selective Monoderivatization of Propane‐1,3‐diamine with Acid Chlorides: ‘Hexahydropyrimidine method’ vs. statistic methods
Authors: Jentgens Christian , Bienz Stefan , Hesse Manfred 
Published: December 2004

AbstractThe selective N‐monoderivatization of propane‐1,3‐diamine (5) with carbonyl and sulfonyl chlorides via2‐phenylhexahydropyrimidine (6) was compared with the direct statistic monoderivatization. It was found that, under optimized conditions, both methods are competitive to one another, depending, however, strongly on the reactivity of the eleclrophile used. The ‘hexahydropyrimidine method’ is more reliable with respect to yields, which are moderate but invariably between 54 and 69%, whereas the ‘statistic method’ leads in certain cases to exceptionally high yields (up to 96%), in others, however, almost none.
Synthesis via a Carbohydrate‐Derived Münchnone of Pyrrolopyridines (Indolizines) and imidazopyridines, and their evaluation as inhibitors of β‐D‐glucosidases
Authors: Granier Thierry , Gaiser Florian , Hintermann Lukas , Vasella Andrea 
Published: December 2004

AbstractIn the presence of activating agents, the N‐acylglycine 8 reacts with electrophilic alkynes via the münchnone9 to the pyrrolopyridines (= indolizines) 10, 18, and 19 (Scheme 1 ), Depending on the nature of the activating agent and the reaction temperature, the formation of the pyrroles was accompanied by partial epimerization to the manna‐configurated epimers 16 and 17. The gluco‐configurated pyrrolopyridine 10 was deprotected to 12. Silylation of 12, followed by reduction and desilylation, gave the hexol 15. Cycloaddition of 9 to 4‐toluenesulfonyl cyanide yielded 53% of the imidazole 23, while cycloaddition to phenyl cyanate gave the phenoxyimidazole 28 in low yields only (Scheme 2). As expected, the deprotected pyrroles 12, 15, 20, and 21 are weak inhibitors of retaining β‐glucosidases, while the deprotected imidazole 24 derived from 23 proved a good inhibitor of sweet‐almond β‐glucosidases and a powerful inhibitor of Caldocellum saccharolyticum β‐glucosidase.
Synthesis of Polysubstituted Pyrrolizidines from Proline Derivatives and Conjugated Nitroolefins
Authors: Felluga Fulvia , Pitacco Giuliana , Visintin Cristina , Valentin Ennio 
Published: December 2004

AbstractThe stereochemistry of 1,3‐dipolar cycloaddition of azomethine ylides derived from aromatic aldehydes and i‐proline alkyl esters with several nitroolefins was investigated. Cyclic and acyclic nitroolefins add to the anti form of the ylide in a highly diastereoselective but poorly regioselective manner to give pyrrolizidine derivatives. In a few cases, the stereochemical results strongly support a stepwise mechanism.
Synthesis of a Novel Tricyclic Dipeptide Template and Its Incorporation into a Cyclic Peptide Mimetic Containing an NPNA Motif
Authors: Pfeifer Marc E. , Linden Anthony , Robinson John A. 
Published: December 2004

AbstractA novel tricyclic dipeptide template, formally derived by coupling (2S,4S)‐4‐aminoproline (Pro(NH2)) and (S)‐2‐(carboxymethyl)proline (Pro(CH2COOH)) as a diketopiperazine, has been synthesized in a form suitable for solid‐phase peptide synthesis using Fmoc chemistry. This template was incorporated into the cyclic molecule cyclo(‐Ala1‐Asn2‐Pro3‐Asn4‐Ala5‐Ala6‐Temp‐) (Temp = template), whose conformation in H2O was studied by NMR methods. Average solution structures derived by restrained simulated annealing point to a highly populated βI‐turn within the Asn‐Pro‐Asn‐Ala motif and also indicate which conformations are likely to be preferred by the template.
Aza‐Claisen Rearrangement: Synthesis of 5′‐branched 5′‐aminothymidines
Authors: Ammenn Jochen , Altmann Karl‐Heinz , Belluš Daniel 
Published: December 2004

AbstractThe syntheses of both diastereoisomers of 5′‐ethyl‐substituted thymidine dimers, the (5′R)‐ and (5′S)‐configurated 33a and 33b respectively, in which the natural phosphodiester linkage is replaced by an amide group (C(3′)‐CH2CONH‐CH(5′)(Et)), arc described. Their fully protected derivatives 35a and 35b, respectively, are suitable for incorporation into antisense oligonucleotides. Unexpectedly, an attempted PdII‐catalysed aza‐Claisen rearrangement of trichloroacetimidate 7 provided the diastereoisomerically pure cyclopropane derivative 17, whose structure was confirmed by X‐ray analysis.
Neue Wege zu Pentalen‐Vorstufen
Authors: You Shaochun , Chai Shengyong , Schwarz Nadine , Neuenschwander Markus 
Published: December 2004

New Pathways to Precursors of PentalenePentalene dimers 2 and 3 are easily available in moderate yields by CuCl2‐induced oxidative coupling of dilithium‐pentalenediide (5) (Scheme 1). On the other hand, NBS bromination of 1,5‐dihydropentalene (4) or of 1,2‐dihydropentalene (8) gives unstable 1‐bromo‐1,2‐dihydropentalene (9), while subsequent in‐situ elimination with Et3N exclusively gives syn‐cis‐pentalene dimer 2 in moderate yields (Scheme 3). NMR‐Spectroscopic evidence for compounds 2, 3, and 9 is presented, and mechanistic alternatives for the formation of pentalene dimers 2 and 3 are discussed.
Syntheses and Properties of Donor/Acceptor Arylethynyl‐Substituted 1, 6‐Methano[10]annulenes
Authors: Bryant‐Friedrich Amanda C. , Neidlein Richard 
Published: December 2004

AbstractThe stepwise palladium‐catalyzed coupling of dibromo‐1,6‐methano[10]annulene derivatives to a phenyl‐acetylene substituted by an electron‐withdrawing group followed by coupling with a phenylacetylene possessing an electron‐donating group allows the preparation of donor/acceptor systems which contain three aromatic moieties linked by ethynediyl bridges. The same type of cross‐coupling starting from 2‐ethynyl‐1,6‐methano[10]annulene and bromo‐substituted azobenzene derivatives provides easy access to a new class of azo dyes. The properties of these compounds are compared to those of analogous compounds containing only benzene rings.
Dendrimers with Porphyrin Cores: Synthetic models for globular heme proteins
Authors: Dandliker Peter J. , Diederich François , Zingg Adrien , Gisselbrecht Jean‐Paul , Gross Maurice , Louati Alain , Sanford Elizabeth 
Published: December 2004

AbstractDendritic iron porphyrins were synthesized as functional mimics of globular electron‐transfer heme proteins. The cascade molecules 1 · Zn−3 Zn of first to third generation were obtained starting from the (meso‐diarylporphyrin) zinc 6 · Zn which contains four carboxylate arms for attachment of the poly(ether‐amide) dendritic branches by peptide‐coupling methodology (Scheme 1). Generation 3 compound 3 · Zn with 108 methyl‐carboxylate end groups has a molecular weight of 19054. D, and computer modeling suggests that its structure is globular and densely‐packed, measuring ca. 4 nm in diameter and, therefore, similar in dimensions to the electron‐transfer protein cytochrome‐c. Starting from the generation 1 poly(carboxylic acid) 11 · Zn and the generation 2 analog 12 · Zn the dendritic ZnII porphyrins 4 · Zn and 5 · Zn, respectively, were obtained by esterification with triethyleneglycol monomethyl ether (Schemes 3 and 4). Demetallation followed by insertion of FeII and in situ oxidation afforded the water‐soluble dendritic iron porphyrins 4 FeCl and 5 FeCl. The electrochemical behavior of esters 1 · Zn−3 · Zn in organic solvents changed smoothly with increasing dendritic generation (Table 1). Progressing from 1 · Zn to 3 · Zn in THF, the first porphyrin‐centered oxidation and reduction potentials become more negative by 320 and 210mV, respectively. These changes were attributed to strong microenvironmental effects imposed on the electroactive core by the densely packed dendritic surroundings. The electrochemical properties of 4 · FeCl and 5 · FeCl were investigated by cyclic voltammetry in both CH2Cl2 and H2O (Tables 2 and 3). Progressing from 4 · FeCl to 5 · FeCl in CH2Cl2, the redox potential of the biologically relevant FeIII/FeII couple remained virtually unchanged, whereas in aqueous solution, 5 FeCl exhibited a potential 420 mV more positive than did 4 FeCl. The large difference between these potentials in H2O was attributed to differences in solvation of the core electrophore. Whereas the relatively open dendritic branches in 4 · Fecl do not impede access of bulk solvent to the central core, the densely packed dendritic superstructure of 5 · FeCl significantly reduces contact between the heme and external solvent. As a result, the more charged FeIII state is destabilized relative to FeII, and the redox potential is strongly shifted to a more positive value.
Determination of the Chemical Structure of novel colored 1H‐pyrrol‐3(2H)‐one derivatives formed by Maillard‐type reactions
Authors: Hofmann Thomas 
Published: December 2004

AbstractThe determination of the chemical structure of a previously unknown Maillard reaction product with an amino acid incorporated in a four‐ring structure is reported. The red compounds 1a and 1b, isolated from a thermally treated aqueous solution of furan‐2‐carbaldehyde and L‐alanine, were identified as (S)‐4{(E)‐1‐formyl ‐2‐(2‐furyl)ethenyl}‐5‐(2‐furyl)‐2‐{(E)‐(2‐furyl)methylidene}‐2, 3‐dihydro‐α‐methyl‐3‐oxo‐1H‐pyrrole‐1‐acetic acid and its 2‐{(Z)‐(2‐furyl)methylidene}isomer, respectively, by several 1D‐ and 2D‐NMR techniques, MS, UV, and IR spectroscopy as well as by synthetic experiments. 2D‐NOESY and 2D‐ROESY experiments performed for conformation analysis indicated the existence of two atropisomers.
New ethylzinc reagents with remarkable properties in palladium‐catalyzed zinc‐ene reactions
Authors: Oppolzer Wolfgang , Schröder Fridtjof , Kahl SÖNke 
Published: December 2004

AbstractPd‐Catalyzed Zn‐ene allylic olefinations with the new ethylzinc reagents EtZnOSO2CF3 (4) and EtZnOC(O)CF(MeO)CF3 (5) in CH2Cl2 showed an unexpected trans‐selectivity in the ring closure to cyclopentane derivatives (see Scheme 2 and Table 1). This strong trans‐selectivity is in contrast with the corresponding known Zn‐ene reaction using Et2Zn in Et2O which shows a high cis‐selectivity (Table 1). The probable radical origin of the observed trans‐selectivity is discussed. The Zn‐ene reaction products of the type RZnOSO2CF3 could be derivatized by the known protonation, iodination, and cyanation yielding 8–10 (Scheme 4 and Table 2), these derivatizations could furthermore be extended by allylation and oxidation reaction (→ 13, 15, and 16; see Scheme 5).
Synthese von triafulvalen‐vorstufen durch ‘carben‐dimerisierung’ von 1‐halogeno‐1‐lithiocyclopropanen
Authors: Läng Christoph , Mühlebach Michel , Neuenschwander Markus 
Published: December 2004

Synthesis of Triafulvalene Precursors by ‘Carbene‐Dimerization’ of 1‐Halogeno‐1‐lithiocyclopropanesBi(cyclopropylidenes) 7a, 7c, and 7e are available in a simple one‐pot reaction by treating 1,1‐dibromocyclo‐propanes 5 at −95° with BuLi and CuCl2. Attempts towards triafulvalene precursors with good leaving groups are reported. The most promising attempt makes use of 2,2′‐bis(phenylthio)‐3,3′‐bis(trimethylsilyl)‐1,1′‐bi(cyclopropylidene) (7c) which has been oxidized to give the bis(phenylsulfonyl) derivative 7g. So far, F−‐induced elimination experiments with 7g failed.
NMR of enaminones. Part 71H‐, 13C‐, and 17O‐NMR and X‐ray structure determinations of 1,2‐disubstituted conjugated 3‐[(tert‐Butyl)amino]enones
Authors: Zhuo Jin‐Cong , Schenk Kurt 
Published: December 2004

Abstract1H‐, 13C‐, and 17O‐NMR spectra for the 2‐substituted enaminones MeC(O)C(Me)CHNH(t‐Bu) (1), EtC(O)C(Me)CHNH(t‐Bu) (2), PhC(O)C(Me)CHNH(t‐Bu) (3), and MeC(O)C(Me)CHNH(t‐Bu) (4) are reported. These data show that 3 exists mainly in the (E)‐form, 4 in (Z)‐form, and 1 and 2 as mixtures of both forms. Polar solvents favour the (E)‐form. The (Z)‐ and (E)‐forms exist in the 1,2‐syn,3,N‐anti and 1,2‐anti,1,N‐anti conformations A and B, respectively. The structures of the (E)‐ and (Z)‐form are confirmed by X‐ray crystal‐structure determinations of 3 and 4. The shielding of the carbonyl O‐atom in the 17O‐NMR spectrum by intramolecular H‐bonding (ΔλHB) ranging from −28 to −41 ppm, depends on the substituents at C(l) and C(2). Crystals of 3 at 90 K are monoclinic. with a = 9.618(2) Å, b = 15.792(3) Å, c = 16.705(3) Å, and β = 94.44(3)°, and the space group is P21/c with Z = 8 (refinement to R = 0.0701 on 3387 independent reflections). Crystals of 4 at 101 K are monoclinic, with a = 16.625(8) Å, b = 8.637(6) Å, c = 11.024(7) Å, and β = 101.60(5)°, and the space group is Cc with Z = 4 (refinement to R = 0.0595 on 2106 independent reflections).
Enantioselective Alternating Terpolymerization of Styrene and Ethene with Carbon Monoxide. Preliminary communication
Authors: Aeby Anton , Consiglio Giambattista 
Published: December 2004

AbstractIn spite of the higher reactivity of styrene with respect to ethene for the alternating copolymerization with carbon monoxide, catalyzed by chiral (dihydrooxazole)(phosphino)palladium complexes, ethene is preferentially (and randomly) enchained in terpolymerization experiments; enantioface selection for styrene is comparably high in both copolymerization and terpolymerization processes.
8,19‐Dimethyl‐tetraepoxy[22]annulen(2.1.2.1): ein erstes Tetraepoxy‐Verbrücktes aromatisches [22]Annulen
Authors: Märkl Gottfried , Ehrl Robert , Kreitmeier Peter , Burgemeister Thomas 
Published: December 2004

8,19‐Dimethyl‐tetraepoxy[22]annulen(2.1.2.1): The First Tetraepoxy‐Bridged Aromatic[22]AnnuleneBy McMurry reaction of 5,5′‐ethylidenebis[furan‐2‐carbaldehyde] (15), a syn/anti mixture 16 of (E,E)‐ and (Z,Z)‐8,19‐dihydro‐8,19‐dimethyl‐tetraepoxy[22]annulene is obtained. The (E/E)‐isomers 16 are the first rotation‐ ally active noncyclic conjugated macrocycles, where the (E)‐ethenediyl moieties rotate around the connecting single bonds. The dihydro‐tetraepoxy[22]annulenes 16 are dehydrogenated by (Ph3C)BF4 as well as by O2 to give the tetraepoxy[22]annulene 11. The spectroscopic data support the character of 11 as an aromatic, diatropic ring system, which is rather sensitive towards O2. In the oxidation mixture obtained from 11, beside polymeric products, two compounds 19 and 20 can be isolated, carrying one and two CHO groups, respectively, resulting by oxidation of one or both Me‐groups but having retained the aromatic 22π system of 11.
Synthesis and Evaluation of Indolizine‐Type Inhibitors of N‐acetyl‐β‐D‐glucosaminidases
Authors: Panday Narendra , Granier Thierry , Vasella Andrea 
Published: December 2004

AbstractTo check if the strong inhibition of N‐acetyl‐β‐D‐glucosaminidase by the tetrazole 8 and the imidazoles 9 and 10 correlates with the presence of a heteroatom corresponding to the glycosidic O‐atom, we prepared the GlcNAc‐derived pyrroles (tetrahydroindolizines) 18, 19, 27, 28, 34, and 35, lacking such a heteroatom. For this. the glucose‐derived pyrroles 11–13 were treated with a Lewis acid in the presence of trimethylsilyl azide. Conditions of kinetic control favored the formation of the gluco‐azides 14, 23, and 30, while thermodynamic control favoured the manno‐azides 20, 29, and 36. Reduction of the azides 14, 20, 23, 30, and 36 by Pd/C‐catalyzed hydrogenolysis or, better, with propanedithiol and Et3N, followed by acetylation or trifluoroacetylation and hydrogenolytic debenzylation, gave the deprotected acetamido‐ and trifluoroacetamido‐pyrroles 18, 19, 22, 27, 28, 34, 35 40, and 41. As compared to the tetrazole 8 and the imidazole 9, the pyrroles 18, 19, 27, 28, 34, and 35 are only modest inhibitors of N‐acetyl‐β‐D‐glucosaminidase from bovine kidney (Ki values between 10 and 75 μM). indicating the necessity of a heteroatom at the glycosidic position. Ki Values between 100 and 160 μM for the inhibition of N‐acetyl‐β‐D‐glucosaminidase from jack beans were determined for the pyrroles 19, 34, and 35. The trifluoroacetamides inhibited both enzymes about twice as strongly as the corresponding acetamides.
Protonic Quantum Correlations in the H‐Bond Dynamics of Nucleic Acids. Part II. Correlations along the helical axis of protein‐coding DNA of living organisms
Authors: Chatzidimitriou‐Dreismann C. Aris , Seifert Daniel 
Published: December 2004

AbstractDue to their small mass, adjacent protons (or H‐atoms) of molecular systems may exhibit quantum entanglement (or quantum correlations), even at ambient conditions. The considerable thermal disturbance and/or manybody interactions of condensed matter and the associated decoherence effect, however, cause this protonic entanglement to be restricted in space and time. Some aspects of entanglement and decoherence are mentioned. Extending our previous theoretical work, in the present paper the focus is on the possible existence of entangled protons belonging to the H‐bonds of adjacent base pairs of B‐type DNA. Based on the ‘working hypothesis’ that this effect does really exist, the most probable ‘positions’ for the appearance of protonic entanglement in DNA sequences are qualitatively determined. Furthermore, these ‘positions’ appear to correspond uniquely to dimers of adjacent base pairs of DNA. As a consequence, one can straightforwardly search for an enhanced appearance of such entangled H‐bonds in DNA sequences of living organisms, using the existing DNA databases. A quantitative analysis of protein‐coding DNA sequences of various organisms has been performed, the results of which provide strong evidence for the existence of the considered effect. The most striking finding may be summarized as follows: Quantum entanglement appears preferably between the third base of a codon and the first base of the following one. Quantitative estimates of this and further obtained results are presented. It is also shown that quantum‐chemical considerations of stacking energies cannot account for the results. The new findings provide first evidence for the biological significance of entangled H‐bonds.
Glycosylidene Carbenes part 26. The intramolecular F…︁HO hydrogen bond of 1,3‐diaxial 3‐fluorocyclohexanols
Authors: Biamonte Marco A. , Vasella Andrea 
Published: December 2004

AbstractAccording to ab‐initio calculations, the CF…︁HO H‐bond in 1,3‐diaxial 3‐fluorocyclohexanol is characterized by d(F…︁H) = 2.08 Å, and ∠ (F…︁HO) = 138°, and by ΔE between 1.2 and 4.1 kcal/mol, depending upon the reference system. Relative to the OH stretching frequency of axial cyclohexanol, the OH stretching frequency of 1,3‐diaxial 3‐fluorocyclohexanol is shifted by Δω = 7 cm−1. The rigid fluoro diols D‐4 and L‐4 were prepared from tetrahydroxy‐p‐benzoquinone in 11 steps and 1% overall yield. The IR spectrum of 4 in CCl4 soln. is characterized by Δν = 7 cm−1 for the axial and Δν = 44 cm−1 for the equatorial OH group. A relatively strong intramolecular CF…︁HO bond of 4 in CCl4 is evidenced by the large through‐space coupling 5J(F,HO) of 9.3 Hz. Nevertheless, this FHO bond is disrupted in ethereal solvents, while the bifurcated O…︁HO bond subsists. In CCl4, the carbene generated from the glucosylidene‐derived diazirine 5 reacted more rapidly with the axial OH group of D‐4 and L‐4 than with the equatorial one. This regioselectivity is in keeping with the weaker H‐bond of the axial OH group. The regioselectivity is lower in ethers, but its solvent dependence does not parallel solvent basicity. This is not satisfactorily explained by the differential interaction of the ether solvents with the axial and equatorial OH groups, as evidenced by the solvent dependence of their chemical shift, but must also reflect the different interaction of the solvents with the carbene derived from 5, leading to ylides. The lower solvent dependence of the anomeric selectivity for the glycosidation of the equatorial OH group is a consequence of the coordination of the intermediate oxycarbenium ion with OC(1) and OC(3) rather than with the solvent. Under conditions of competitive glycosylation in CCl4, the fluoro alcohol D‐22 reacted more slowly than the alcohol L‐24, evidencing the intramolecular F…︁HO H‐bond.
Reaction of N,N'‐dimethyl‐2‐nitroethene‐1, 1‐diamine with α,ß‐unsaturated acyl isothiocyanates: Preparation of 1,3‐thiazin‐4‐one and 4‐nitro‐1,2‐thiazol‐5(2H)‐imine derivatives
Authors: Trimiño María I. García , Cabrera Castro Arturo Macías Hermán Vélez , Rosado Pérez Arístides , Argilagos Dally Moya , Linden Anthony , Heimgartner Heinz 
Published: December 2004

AbstractThe reaction of N,N'‐dimethyl‐2‐nitroethene‐1,1‐diamine (8) with α,ß‐unsaturated acyl isothiocyanates 9 affords 3,3‐diamino‐2‐nitroacrylthioamides 10 (Scheme 2) in moderate‐to‐good yields. Cyclization of 10 under acidic conditions gives 1,3‐thiazin‐4‐one derivatives of type 11. Oxidative cyclization of 10 with diethyl azodicaboxylate leads to 4‐nitro‐1,2‐thiazol‐5(2H)‐imine derivatives 12.
An Alternative Synthesis of the Enantiomerically Pure Competitive NMIDA Antagonists SDZ 220‐581 and SDZ EAB 515
Authors: Müller Werner , Bänziger Markus , Kipfer Peter 
Published: December 2004

AbstractAn alternative synthesis of enantiomerically pure SDZ 220–881 (1a) and SDZ EAB 515 (1b) starting from L‐Z‐tyrosine is described.