bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acetyl‐cobalamin from Photoinduced Carbonylation of Methyl‐cobalamin
Authors: Kräutler Bernhard 
Published: December 2004

AbstractIrradiation with visible light of a deoxygenated aqueous solution of methyl‐cobalamin (1) under an atmosphere of CO and at ambient temperature converts 1 into acetyl‐cobalamin (2). This carbonylation has potential relevance with respect to bacterial acetate biosynthesis from CO2.
The Reaction of Singlet Oxygen with 1,3‐Dimethylindole in the Presence of Aldehydes. Formation of 1,2,4‐Trioxanes
Authors: Jefford Charles W. , Jaggi Danielle , Boukouvalas John , Kohmoto Shigeo , Bernardinelli Gérald 
Published: December 2004

AbstractThe dye‐sensitized photo‐oxygenation of 1,3‐dimethylindole in the presence of aldehydes initially generates a zwitterionic peroxide which condenses with the carbonyl function to give the corresponding cis‐fused 1,2,4‐trioxanes. Acetaldehyde gives a pair of diastereomers, one of whose structures was determined by X‐ray analysis (cis,cisisomer), whereas pivaladehyde gives only the cis,cis diastereomer.
Spectroscopic Characterization of Open‐Shell Cations: Emission and Laser Excitation spectra of Rotationally Cooled CH3(CC)2X+, X = Cl, Br
Authors: Klapstein Dieter , Kuhn Robert , Maier John P. , Misev Liubomir , Ochsner Martin 
Published: December 2004

AbstractGas phase emission and laser excitation spectra of the Ã2E↔X̃2E (Σ = +½, −½) transition of rotationally/vibrationally cooled 1‐chloro‐ and 1‐bromo‐1,3‐pentadiyne cations have been obtained. The emission was excited by electron impact on a seeded helium supersonic free jet and the fluorescence by laser excitation of cations produced by Penning ionization and collisional relaxation. From these two sets of data the origin bands of the spin‐orbit systems are located and for the bromo species this leads to better values of the spin‐orbit splitttings in the two electronic states and of the first adiabatic ionization energy. The vibrational frequencies of many of the fundamentals of these cations in the X̃2E and Ã2E states have been obtained to within ±2 cm−1.
Synthèse facile de dérivés du diphényl‐2,4‐aza‐3‐bicyclo[3.3.1]nonane et du diphényl‐7,8‐aza‐8‐bicyclo[4.3.1]décane
Authors: Campo Carmen Del , Martinez Ernesto , Trigo Gregorio G. 
Published: December 2004

Facile synthesis of derivatives of 2,4‐diphenyl‐3‐azabicyclo[3.3.1]nonane and 7,9‐diphenyl‐8‐azabicyclo[4.3.1]decaneThe facile synthesis of hydantoins, cyanhydrins and aminonitriles derived from 2,4‐diphenyl‐3‐azabicyclo[3.3.1]nonanone and 7,9‐diphenyl‐8‐azabicyclo[4.3.1]decanone is described. Configurations at C(9) or C(10) of the new compounds wth pharmaceutical and synthetical utility is deduced from their spectral properties.
Preparation of Ru(CO)(diene)2 Complexes by Electron‐Beam Evaporation of Ruthenium. Preliminary Communication
Authors: Cox David N. , Roulet Raymond 
Published: December 2004

AbstractRu‐atoms (0.5–1.5 g) have been generated by electron bombardment and, in separate experiments, were co‐condensed at 7 K with excess of 2,3‐dimethylbutadiene or 1,3‐ or 1,4‐cyclohexadiene. The complexes Ru(CO)(η4‐C6H10)2 (1) and Ru(CO)(η4‐C6H8)2 (2), respectively, have been isolated in 25–30% yields on warming the condensate under CO.
Electron‐Transfer‐Induced Conformational Changes. The Example of 1,8‐Dimethyl[14]annulene
Authors: Huber Walter 
Published: December 2004

AbstractThis communication reports ESR‐spectroscopic investigations of the radical anion of 1,8‐dimethyl[14]annulene (1) which possesses a flexible molecular framework allowing configurational and conformational mobility. The ESR and ENDOR spectra indicate that at higher temperatures (T > 160 K), \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{- \atop \dot{}} $\end{document} exists as a mixture of several distinct isomers. One of them, the sole product at T < 160 K, is found to be energetically preferred. The configuration and the conformation of this species can be determined by interpretation of the hyperfine data in terms of a singly occupied MO of the 14‐membered π‐perimeter.
Camphor‐Derived N‐Acryloyl and N‐Crotonoyl Sultams: Practical Activated Dienophiles in Asymmetric Diels‐alder Reactions. Preliminary Communication
Authors: Oppolzer Wolfgang , Chapuis Christian , Bernardinelli Gérald 
Published: December 2004

AbstractStarting from (+)‐camphor‐10‐sulfonyl chloride (5), the crystalline sultam 8 was easily prepared. Lewis‐acid‐promoted Diels‐Alder additions of the crystalline N‐acry‐loyl and N‐crotonoyl derivatives 9 and 10, respectively, to cyclopentadiene and 1,3‐butadiene at −130 to −78° furnished adducts 11, 12 and 17 with high chiral efficiency. Crystallization of the adducts and nondestructive removal of 8 gave either alcohols 13, 14 and 18 ir acid 19 in 99% enantiomeric purity. The sense of induction was reversed on using the enantiomer of 8 as the auxiliary. The structure of 10 was established by X‐ray diffraction analysis.
Fast‐atom‐bombardment mass spectrometry and 1H‐NMR spectrometry in studies of the transformations of thiamine in strongly basic solutions
Authors: Horman Ian 
Published: December 2004

AbstractFast‐atom‐bombardment (FAB) mass spectra have been used to establish or confirm the nature of the yellow‐product and open‐chain forms of thiamine produced in the presence of excess (5 mol‐equivb.) of strong base. Time‐dependent changes in 1H‐NMR spectra show that the rates of disappearance of the yellow form and of formation of the open‐chain form are the same at pH 12.5, having a pseudo‐first‐order rate constant of k = 2.2 × 10−3 sec−1. The implications of these results are discussed in the light of current ideas on the acid‐base dependence of thiamine structures.
Photochemistry of 8,8,9,9‐tetramethyl‐1,3,4,6,7,8‐hexahydro‐1,4‐ethanonaphthalene‐2,5‐dione, a δ‐oxo‐β,γ‐unsaturated ketone
Authors: Kilger Ralf , Körner Wolfgang , Margaretha Paul 
Published: December 2004

AbstractThe oxa‐di‐π‐methane rearrangement product 4,4,9,9‐tetramethyltetracyclo [6.4.0.01,5.02,8]dodecane‐7,12‐dione (2) is formed selectively in a variety of solvents on either direct (λLD = 254, 300, 350 nm) or sensitized (xanthone, acetone, benzene) irradiation of the title compound 1. The efficiency for this rearrangement is higher on So–S1 excitation (Φ−1 = 0.67) than on either So–S2 or So–S3 excitation (Φ−1 = 0.58).
Transition metal complexes with bidentate ligands spanning trans‐positions part XV X‐ray structural and 31P‐NMR solution studies of some three‐coordinate silver complexes of 2,11‐bis[di(tert‐butyl)phosphinomethyl]benzo[c]phenathrene and related ligands
Authors: Camalli Merceds , Caruso Francesco , Chaloupka Stanislav , Kapoor Pramesh N. , Pregosin Paul S. , Venanzi Luigi M. 
Published: December 2004

AbstractA series of three‐coordinate bis(dialkylphosphinomethyl)benzo[c]phenanthrene Ag(I) complexes, alkyl= t‐Bu, (1b), and cyclohexyl, (1c), anion = BF4, CIO4, CIO4, NO3, Cl, Br, I, have been prepared and thier 31P‐NMR characteristics recorded. The solid state structures of [Ag(1b)Br], [Ag(1b)Cl] and [Ag(1b)CIO4] have been determined by X‐ray diffraction. The Ag atom in these complexes shows distorted trigonal geometry. Selected bond lengths and angles are as follows: Ag‐P = 2.463(4) Å and 2.433(5) Å, P‐Ag‐P=141.6(2)° in the bromo complex, Ag‐P = 2.457(2) Å and 2.427(2) Å, P‐Ag‐P = 142.6(1)° ion the chloro complex, and Ag‐P = 2.394(2) and 2.393 (2) Å, P‐AG‐P = 161.5(1)° in the perchlorato complex.
Optical resolution of 7‐oxabicyclo[2.2.1]hept‐21‐ene derivatives. Diastereoselectivity in the formation of cyanohydrine‐brucine complexes
Authors: Black Kersey A. , Vogel Pierre 
Published: December 2004

AbstractA new, practical method for the optical resolution of bicyclic ketones if illusttrated by the preparation of (+)‐(1R,4R)‐7‐oxabicyclo[2.2.1]bept‐5‐en‐2‐one ((+)‐1) and (+)‐(1R, 2S,4R)‐2‐cyano‐7‐oxabicyclo[2.2.1]hept‐5‐en‐2‐yul acetate ((+)‐4). It involves the diastereoselective formation of a brucine complex with the corresponding cyanhydrine mixture.
Hydroxyalkylierungen von Cystein über das Enolat von (2R,5R)‐2(tert‐Butyl)‐1‐aza‐3‐oxa‐7‐thiabicyclo[3.3.0]octan‐4‐on und unter Selbstreproduktion des Ciralitätszentrums
Authors: Seebach Dieter , Weber Theodor 
Published: December 2004

AbstractHydroxyalkylations of Cysteine through the Enolate of (2R,5R)‐2(tert‐Butyl)‐1‐aza‐3‐oxa‐7‐thiabicyclo[3.3.0]octan‐4‐one with Self‐Reproduction of the Center of ChiralityThe heterobicyclic compound 1 specified in the title is readily prepared as a single stereoisomer from (R)‐cysteine, formaldehyde, and pivalaldhyde. While it is not possible to generate the enolate 10 from 1 qunatitatively – due to β‐elimination of thiolate (→6) – an in‐situ addition to aromatic aldehydes such as benzaldehydes (→13–16), pyrrol‐, furan‐, and thiophen‐2‐carbaldehydes (→17–19), pyridine‐3‐carbaldehyde (→21), as well as to other non‐enolizable aldehydes like cinnamaldehyde (→22), can be achieved in yields of ca. 50%. The adducts (8 and 9) of lithium diisopropylamide or t‐butoxide to these aldehydes are acting, probably as bases for deprotonation and as in‐situ sources of the electrophilic aldehyde species (cf. 11, 12). ‐ Of the four possible diastereoisomeric products, one is usually formed with >90% selectivity (Table). It is assumed that the preferred stereochemical course of the reaction corresponds to that observed previously with the analogous proline‐derived enolate (See 23,24). A chemical correlation with l‐α‐methyl‐β‐phenylserine (25) proves the relative configuration of the benzaldehyde adduct 13. All hydroxyalkylated products (13–19, 21, 22) are obtained as crystalline, diastereoisomerically pure compounds and are fully characterized. – The benzaldehyde derivative 13 was used to exemplify the various possible transformations of these products to monocyclic or acyclic amino‐acid derivatives such as the oxazolidionenes 26 and 29 (cleavage of the ring containing the S‐atom), the thiazolidines 28, 31, and 32 (cleavage of the cyclic N,O‐acetal) and the α‐branched cysteine 27 and the phenylserines 25 and 30 (cleavage of both rings to give open‐chain aminoacids).
Electrostatic Defromation Properties in the Crystal Structure of Tricyclo[4.4.1.01,6]undeca‐2,4,7,9‐tetraene‐11,11‐dicarbonitrile
Authors: Bianchi Riccardo , Pilati Tullio , Simonetta Massimo 
Published: December 2004

AbstractThe deformation density and potential have been determined in molecular crystals of tricyclo[4.4.1.01,6]ndeca‐2,4,7,9‐tetraene‐11,11‐dicarbonitrile at 150 K from X‐ray diffraction measurements. A significant degformation density peak is found near the mid‐poind of the the transannular bond. The four short bonds in the annuelene ring acquire slightly more residual density compared to the other bonds, confirming the bisnorcaradienic character of the molecule. Similar trends are noted in the deformation electrostatic potential maps.
Photochemical reactions. 140th Communication. Acid‐catalyzed rearrangement and electron transfer photooxygenation of cyclopropanols and their silyl ethers
Authors: Scheller Markus E. , Mathies Peter , Petter Walter , Frei Bruno 
Published: December 2004

AbstractOn acid‐catalyzed hydrolysis, the tricyclic compounds 2 and 10, incorporating cyclopropyl‐silyl‐ether moieties undergo rearrangement to the cis‐decalones 3 and 7, respectively. Hydrolysis of 2 and 10 in the presence of oxygen leads additionally to the formation of the 1,2‐dioxolan‐3‐ols 9 and 13, respectively, which involves an electron‐transfer oxygenation process as could be demonstrated by photooxygenation of the silyl ether 10 and the cyclopropanol 14 in the presence of 9,10‐dicyanoanthracene. The configurations of 3 and 9 were assigned by X‐ray analysis of the latter compound as well as of the p‐nitrobenzoate 8 of 3.
Synthese des Dysidins
Authors: Köhler Hermann , Gerlach Hans 
Published: December 2004

Synthesis of DysidinThe synthesis of dysidin ((−)‐1), the enantiomer of a metabolite of the marine sponge Dysidea herbacea, is described. To effect the synthesis, (±)‐5‐isopropyl‐4‐methoxy‐3‐pyrrolin‐2‐one (7) is converted to its lithium salt and reacted with (−)‐(5R,2E)‐3‐methoxy‐5‐trichloromethyl‐2‐hexenoyl chloride ((‐)‐11) to give (−)‐1 and its diastereoisomer (+)‐5‐epidysidin ((+)‐12) epimeric at C(5) of the pyrrolinone ring. The (−)‐acyl chloride (−)‐11 has been synthesized from (+)‐(R)‐3‐(trichloromethyl)butanoic acid ((+)‐8) via the intermediates (+)‐9 and (−)‐10, the pyrrolinone 7 from N‐benzyl‐oxycarbonyl‐L‐valine via the intermediate 5. The enantiomers of acid 8 have been resolved by fractional crystallization of their diastereoisomeric N‐(1‐phenylethyl)amides. The (R)‐chirality of (+)‐8 was determined by comparing the 1H‐NMR spectra of the diastereoisomeric N‐(1‐phenylethyl)amides 16 and 17, made from (+)‐8 by substituting deuterium for chlorine, with the spectra of the N‐(1‐phenylethyl)amides 14 and 15 of known absolute configuration. This correlation shows that literature value (R) for (−)‐8 is in error. Therefore, the structural formulae of (−)‐dysidenin and (+)‐isodysidenin, two other metabolites of D.herbacea, have to be changed to their mirror images as shown in formulae (−)‐3 and (+)‐4, respectively.
Light‐induced Dehydrodimerization of 3‐Hydroxypyrroles
Authors: Ghaffari‐Tabrizi Ramin , Margaretha Paul , Schmalle Helmut W. 
Published: December 2004

AbstractIrradiation (λ > 280 nm) of 3‐hydroxy‐1H‐pyrrole‐2‐carboxylates 1 in CH3CN gives the [2.2′‐bi(3‐oxo‐2,3‐dihydro‐1H‐pyrrole)]‐2‐,2′‐dicarboxylates 2 in reasonable to good yields. The corresponding N‐methylpyrroles 3 only undergo slow photodecomposition under similar conditions. Several 2‐methyl‐3‐oxo‐2,3‐dihydro‐1H‐pyrrole‐2‐carboxylates 4 and 5 were synthesized to compare their spectral data with those of the dehydrodimers 2. A X‐ray structure analysis was performed for diethyl [2,2′‐bi(4,5‐dimethyl‐3‐oxo‐2,3‐dihydro‐1 H‐pyrrole)]‐2,2′‐dicarboxylate (2b). The originally proposed [3,3′‐bi(3H‐pyroole)] structure for compounds 2a‐e proves incorrect.
Conversion of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (mptp) and its 5‐methyl analog into pyridinium salts
Authors: Gessner Wieslaw , Brossi Arnold , Shen Rong‐Sen , Fritz Richard R. , Abell Creed W. 
Published: December 2004

AbstractMonoamine oxidase B metabolizes 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP; 1) first to 1‐methyl‐4‐phenyl‐2,3‐dihydropyridinium salt (MPDP+; 5), and then to 1‐methyl‐4‐phenylphridinium salt (MPP+; 7). Chemical synthesis of MPDP+ and its 5‐methyl analog 6 was accomplished from the N‐oxides 3 and 4 of MPTP and its 5‐methyl analog, respectively, by a Polonovski reaction. Oxidation of MPDP+ to MPPM+ was accomplished with air, and greatly accelerated by Pt catalyst. Reduction of MPDP+ and MPP+ with NaBH4 afforded MPTP.
The Synthesis and Structure of Pentacarbonyl (5H‐dipyrrolo[1,2‐c: 2′,1′‐e]imidazol‐5‐yl)manganese
Authors: Burger Ulrich , Perret Celia , Bernardinelli Gérald , Kündig E. Peter 
Published: December 2004

AbstractThe dipyrroloimidazolyl ligand is found to bind the pentacarbonylmanganese group to its central ring via a carbon‐metal σ‐bond. This bonding mode differs greatly from that of known imidazole complexes and from the pentahapto mode encountered with the isoelectronic fluorenyl ligand. The X‐ray structure of the title compound is reported.
Cuprous complexes and dioxygen. Part X. Influence of ring size on the autoxidation of Cu(I) complexes with cis‐and trans‐N2S2 macrocyclic ligands
Authors: Balakrishnan Karappulli P. , Zuberbühler Andreas D. 
Published: December 2004

AbstractThe autoxidation of the Cu+ complexes with a series of six 12‐, 14‐ and 16‐membered macrocycles containing the N2S2 set of donor atoms has been studied with an oxygen electrode and with the stopped‐flow technique. Inspite of the identical set of coordinating groups, the reactivity of the Cu= complexes towards O2 varies by more than 5 orders of magnitude, with rate constants between <0.1 and 2·104 M−1S−1. Simple bimolecular rate laws are obtained from initial rates of autoxidation, but successive one‐electron transfers with intermediate formation of superoxide are implied from the analysis of complete reaction curves for complexes with the 12‐membered macrocycles. The kinetic parameters are compared with the redox potentials for the corresponding CuL2+/CuL+ couples. Only a rather rough correlation is found and steric factors must in addition be responsible for the observed reactivity pattern which shows a decrease of autoxidation rate with increasing size of the macrocyclic ring. No systematic effect was observed for the influence of cis‐ vs. trans‐configuration of the donor atoms.
Substitution électrophile aromatique dans l'anhydride sulfureux liquide. Influence de la concentration en bromure et rôle du solvant sur la réactivité des anisoles au cours de la réaction de bromation
Authors: Castellonése Paul , Villa Pierre 
Published: December 2004

AbstractElectrophilic Aromatic Substitution in Liquid Sulfur Dioxide. Kinetic Dependance of Rate on the Bromide Concentration and Influence of the Solvent during the Course of the ReactionOn the reported data for bromination of anisole and eleven of its derivatives in liquid SO2, it was shown that, with a large excess of bromide, the rate of reaction, obeys a first‐order law. Rate constants thus obtained do not discriminate between the two different forms of bromide, e.g. Br2 and Br−3 present as the A+Br−3 form, and corrections were made by use of the apparent equilibrium constant K′ for tribromide formation. The variations of rate constants with initial concentration of bromide has been studied and the effect results in a retardation of the bromination rate. Moreover, the ratio [Br2] [A+Br−]T, which is constant during an experiment, varies with initial bromide concentrations, this variation affecting the total rate. To account for the bromide effect on the reactivity, variations of ko,pg {1 + K′[A+Br−]T}VS[A+Br−]T were studied over a 0.01 to 1M range of bromide concentration. The mechanism proposed shows that liquid SO2 helps the reactive intermediate to be deprotonated and because of solvation of reactive species this step would probably be rate determining. Bromination by molecular bromine is more sensitive to substituent effects in liquid SO2 than in water. This result is ascribed to the +M effect of the methoxy group which increase the conjugation of ortho‐substituted derivatives (p+p = −7.83; p+o= −10.47).
Eine Neuuntersuchung der Carotinoide aus Rosa foetida: Struktur von 12 neuen Carotinoiden; stereoisomere Luteoxanthine, Auroxanthine, Latoxanthine und Latochrome
Authors: Märki‐Fischer Edith , Buchecker Richard , Eugster Conrad Hans 
Published: December 2004

AbstractReinvestigation of the Carotenoids from Rosa foetida, structures of 12 Novel Carotenoids; Stereoisomeric Luteoxanthins, Auroxanthins, Latoxanthins and LatochromesFrom petals of the yellow Rosa foetida HERRM., more than 35 individual carotenoids were isolated and identified. Thereof, 87% belong to the expoxycarotenes. Structures were assigned for the first time to 4 auroxanthins ((8R,8′S), 6; (8S,8′S), 7; (8R,8′R), 8; (9Z,8R,8′R), 12), to 4 luteoxanthins ((8′R), 4; (8′S), 5; (9Z,8′R), 9; (9Z,8′S) 10(e)) and to novel latoxanthins and latochromes, very polar carotenoids having (3S,5R,6R)‐trihydroxy β‐end groups (latoxanthins 13 and 16, latochromes 14 and 15).
Hyperbolic Reaction Curves with Concentration‐Independent Relaxation Times
Authors: Balakrishnan Karappulli P. , Gampp Harald , Zuberbühler Andreas D. 
Published: December 2004

AbstractHyperbolic reaction curves with concentration‐independent relaxation times are obtained from the simple reaction scheme A⇌I + P; A + I → P. While a mathematically perfect hyperbola is only obtained, if two of the three rate constants are accidentally degenerate, the same function can still be used as a very close approximation in the general case, and the differences may go unnoticed even for well‐defined stopped‐flow experiments. In view of the simplicity of the reaction, it is suggested that reaction curves with second‐order (hyperbolic) shapes, but concentration‐independent relaxation times may be a common feature in chemical kinetics.
Luteochrome; spektroskopische, chiroptische und chromatographische Eigenschaften
Authors: Acemoglu Murat , Eugster Conrad Hans 
Published: December 2004

AbstractTwo Optically Active Luteochromes: Preparation, Spectra and Chiroptical and Chromatographic PropertiesSelective rearrangement of (5R,6S,5′ R,6′S)‐5,6:5′, 6′ ‐diepoxy‐5,6,5′, 6′ ‐tetrahydro‐ β,β ‐carotene with the aid ofan ethereal solution of malonic acid leads to the mixture of the C(8′)‐epimeric luteochromes. HPLC separation gave the pure isomers. This is the first report on th preparation of optically active luteochromes.
Gerüstumlagerung eines α,β ‐ungesättigten γ,δ‐Epoxiketons bei der Birch‐Reduktion: Strukturaufklärung mittels 13C‐INADEQUATE‐NMR‐Spektroskopie
Authors: Kreiser Wolfgang , Rüschenbaum Voker , Bauer Hans , Buddrus Joachim 
Published: December 2004

AbstractSkeleton Rearrangement of an α‐β‐Unsaturated γ,δ‐Epoxyketone during Birch Reduction: Structure Elucidation by Means of 13C‐INADEQUATE‐NMR SpectroscopyWhen the γ‐epoxide 2 of β‐ionone is treated under standard Birch‐reduction conditions, unexpectedly a 70% combined yield of regioisomeric octalones 4 and 5 is isolated. These products unquestionably result form cleavage of the central epoxide CC bond. The structure of compounds 4 and 5 could be determined by means of 13C‐INADEQUATE‐NMR spectroscopy.
Aromatization of 1,4‐Dihydropyridines by Clay‐Supported Metal Nitrates
Authors: Balogh Maria , Hermecz Iatván , Ménszáros Zoltán , Laszlo Pierre 
Published: December 2004

Abstract1,4‐Dihydropyridines can be aromatized under very mild conditions by K 10 Claysupported ferric and cupric nitrates.
Melanotropin Receptors I. Synthesis and Biological Activity of Nα‐(5‐Bromovaleryl)‐Nα‐deacetyl‐α‐melanotropin
Authors: Wunderlin Rudolf , Minakakis Panagiota , Tun‐Kyi Aung , Sharma Shub Dev , Schwyzer Robert 
Published: December 2004

AbstractChemical synthesis and biological activities of a new α‐melanotropin derivative are described. Nα‐(5‐Bromovaleryl)‐Nα‐deacetyl‐α‐melanotropin contains the 5‐bromopentanoyl group as a chemical ‘handle’ in place of the acetyl group of the natural hormone. The synthesis involved a new protected intermediate which allowed the selective deprotection of either the Nα or Nα amino group. The title compound reacted with sodium thiosulfate to give Nα‐deacetyl‐Nα‐(5‐(sulfothio)valeryl)‐α‐melanotropin, a key intermediate for the preparation of tobaccomosaic virus/α‐melanotropin disulfide conjugates. As a basis for the study of the conjugates, biological activities of the title compound on Cloudman S‐91 mouse melanoma cell cultures (tyrosinase stimulation, binding, and cyclic AMP accumulation) were determined. They proved to be quite similar to the corresponding α‐melanotropin activities. Differences in bindings may be explained by stronger hydrophobic interaction of the new derivative with the lipid phase of the target cell membranes.