bluuebunny/crossref_metadata_2025 huggingface dataset:
Organische Phosphorverbindungen XXXVIII. Darstellung und Eigenschaften von Tris‐(dialkoxyphosphonyl‐methyl)‐, Tris‐(alkoxyphosphinyl‐methyl)‐und Tris‐(oxophosphoranyl‐methyl)‐phosphinsäureestern sowie der entsprechenden Säuren [1]
Authors: Maier Ludwig
Published: December 2004

Tris‐chloromethyl‐phosphine oxide, (ClCH2)3 PO(I), is obtained by chlorination of (HOCH2)3PO with PCl5 or (C6H5)3PCl2, and also by oxidation of (CICH2)3PO and (ClCh2)2(CH3)PO. High yields of tris‐(dialkyloxyphosphonly‐methyl)‐phosphine oxides, [RO2(O)PCH2]2PO (II) (RCH3, C2H5, iso‐C3H7, n‐C4H9, 2‐ ethyl‐hexyl), tris (alkyloxyphosphinyl‐methyl)‐phosphine oxides, [R2(O)PCH2]3PO(R = C6H5, CH3) are obtained by heating tris‐chloromethyl‐phosphine oxides, [(RO) (R′) (O)PCH2]3PO (R = C4H9, R′ C6H5) and tris‐(oxophosphoranyl‐phosphine oxides with phosphites, phosphonites and phosphinites, respectively, at 170–180°C for several hours. Compounds II possess an extraordinarily high absorption capacity. Thus a warm. 2% solution of II (R = C2H5) in benzene solidifies completely on cooling so that no benzene can be poured off.

Tris‐dihydroxyphosphonyl‐methyl)‐phosphine oxide, [(HO)2(O)PCH2]3PO, obtained by hydrolysis of II (R  C2H5) with refluxing conc. HCl or by thermal decomposition of II (R  iso‐C3H7) at 190°, titrates in aqueous solution as a hexabasic acid with breaks at pH = 4,4 (three equivalents) and pH = 10,7 (three equivalents). It forms crystalline salts with amines, alkali and alkaline earth metals, and is an excellent chelating agent.

The 1H‐ and 31−P‐NMR. spectra of all the compounds prepared are discussed.
Photochemische Reaktionen. 52. Mitteilung [1]. Zur Photochemie von α,β‐ungesättigten cyclischen Ketonen: Spezifische Reaktionen der n,π*‐ und π,π*‐Triplettzustände von O‐Acetyl‐testosteron und 10‐Methyl‐Δ1,9‐octalon‐(2)
Authors: Belluš D. , Kearns D. R. , Schaffner K.
Published: December 2004

The photochemistry of the conjugated cyclohexenones O‐acetyl testosterone (1) and 10‐methyl‐Δ1,9‐octalone‐(2) (24) has been investigated in detail. The choice of reaction paths of both ketones depends strongly on the solvent used. In t‐butanol, a photostationary equilibrium 1 ⇄ 3 is reached which is depleted solely by the parallel rearrangement 1 → 5 (Chart 1; for earlier results on these reactions see [2a] [6] [7]). In benzene, double bond shift 1 → 16 (Chart 3) occurs instead, which is due to hydrogen abstraction from a ground‐state ketone by the oxygen of an excited ketone as the primary photochemical process. In toluene, the major reaction is solvent incorporation (1 → 17, Chart 4) through hydrogen addition to the β‐carbon of the enone, accompanied by double bond shift and formation of saturated dihydroketone as the minor reactions. Contrary in part to an earlier report [19], the photochemical transformation of the bicyclic enoné 24 exhibit a similar solvent dependence. The corresponding products 25–29 are summarized in Chart 5 and Table 1.

Sensitization and quenching experiments established the triplet nature of the above reactions of 1 and 24. Based on STERN‐VOLMER analyses of the quenching data (cf. Figures 2, 4–8, and Table 3), rearrangement, double bond reduction and toluene addition are attributed to one triplet state of the enones which is assigned tentatively as 3(π, π*) state, and the double bond shift is attributed to another triplet assigned as 3(n, π*) state (cf. Figure 9).

The stereospecific rearrangement of the 1α‐deuterated ketone 2 to the 4β‐deuterio isomer 4 shows the reaction to proceed with retention at C‐1 and inversion at C‐10.

The 4‐substituted testosterone derivatives 33–36 (Chart 8) were found to be much less reactive in general than 1. In particular, 4‐methyl ketone 33 remains essentially unchanged on irradiation in t‐butanol, benzene and toluene.
Spectres de masse des composés organiques. 4e communication. Fragmentation de l'hexane
Authors: Liardon Rémy , Gäumann Tino
Published: December 2004

With the help of metastable peaks and high resolution, and by making extensive use of deuterated species we determined the main paths of fragmentation of hexane. Beside the simple splitting of a CC‐bond there are a series of internal rearrangement reactions. The loss of neutral fragments from alkyl ions is often, but not always, statistical. A small primary (0.96) and an even smaller (0.99) secondary isotope effect for a hydrogen transfer can be observed.
Kinetische Untersuchungen über Substitutionsreaktionen an Metallkomplexen. 11. Mitteilung [1]. Die Bildung von Tetrakis(triäthylphosphit)nickel(0) aus Nickelocen — eine Reaktion dritter Ordnung
Authors: Werner H. , Harder V. , Deckelmann E.
Published: December 2004

Nickelocene Ni(π‐C5H5)2 reacts with triethylphosphite in dioxane at 50–70° to give Ni[P(OC2H5)3]4. Kinetic studies confirm a third‐order rate law for this ligand substitution process with the activation parameters Ea = 6.8 kcal/mole and ΔS≠ = −53.8 e. u. The mechanistic implications of these results are discussed.
Reaktionen von Bleitetraacetat mit alicyclischen Alkoholen, III. Cyclopropyl‐ und Cyclobutylcarbinole. 18. Mitteilung über Reaktionen mit Bleitetraacetat
Authors: Lj. Mihailović M. , Čekovié Ž.
Published: December 2004

When treated with lead tetraacetate, cyclopropylcarbinol and cyclopropylmethylcarbinol do not give β‐fragmentation products resulting from the intermediate formation of cyclopropyl radicals; however, cyclopropylmethylcarbinol affords a small amount of a fragmentation product which arises from CαCβ bond cleavage involving removal of a methyl radical. In contrast, cyclobutylcarbinol undergoes β‐fragmentation in 18% yield with formation of both the unrearranged cyclobutyl acetate and the rearranged cyclopropylmethyl acetate. These results suggest the following order of increasing radical stability: cyclopropyl < methyl < cyclobutyl, whereas the isolation of the isomeric fragmentation acetates in the lead tetraacetate reaction of cyclobutylcarbinol represents further evidence that in the β‐fragmentation process the initially produced carbon radical fragment is in major part oxidized to the corresponding carbonium ion before final product formation.
Fluoreszierende Stoffe aus Drosophila melanogaster. 14. Mitteilung [1]. Eine Synthese des Biopterins
Authors: Viscontini M. , Provenzale R.
Published: December 2004

2,4,5‐Triamino‐6‐oxo‐1, 6‐dihydropyrimidin wird mit 1‐(Benzylphenylhydrazino)‐5‐desoxy‐L‐ribulose in wässrigem Methanol unter N2 kondensiert. Die Mischung der gebildeten Tetrahydropterine wird zu den entsprechenden Pterinen oxydiert, wobei die polyhydroxyalkylierte Kette teilweise abgespalten wird. Diese Pterine stellen eine Mischung von Biopterin, wenig seines 7‐Isomeren und viel Pterin sensu stricto dar. Aus dieser Mischung lässt sich reines Biopterin durch Chromatographie an Dowex 1 × 8 gewinnen. Das synthetische und das aus Drosophila melanogaster isolierte Biopterin sind völlig identisch.
Le blocage de la lysine par la réaction de MAILLARD. I. Synthèse de N‐(désoxy‐1‐D‐fructosyl‐1)‐ et N‐(désoxy‐1‐D‐lactulosyl‐1)‐L‐lysines
Authors: Finot P. A. , Mauron J.
Published: December 2004

The authors describe a specific method for the preparation of Nϵ‐(1‐deoxy‐D‐fructosyl)‐L‐lysine, Nα‐(1‐deoxy‐D‐fructosyl)‐L‐lysine, their formyl derivatives, and Nα‐formyl‐ϵ‐(1‐deoxy‐D‐lactulosyl)‐L‐lysine, as well as Nα, Nϵ‐di‐(1‐deoxy‐D‐fructosyl)‐L‐lysine. After purification by cation‐exchange chromatography using volatile pyridine‐acetic acid or pyridine‐formic acid buffers, these compounds are obtained in the pure state. By thin‐layer chromatography and paper electrophoresis these lysine derivatives can be rapidly separated and identified.
Die Oxydation von Alkoholen mit Bleitetraacylaten; Einfluss der Acylreste bei der thermischen Reaktion
Authors: Heusler K.
Published: December 2004

The competitive thermal oxidation of a 6β‐hydroxy steroid (to a 6β, 19‐ether) and the thermal oxidative decarboxylation of various carboxylic acids by lead4+ was investigated. The alcohol oxidation is faster than acetate and benzoate oxidation, about as fast as the oxidative decarboxylation of higher primary carboxylic acids (propionic, butyric acid), and much slower than the oxidative decarboxylation of secondary and tertiary carboxylic acids.
δ1‐p‐Menthen‐9‐al, ein Bestandteil des bulgarischen Rosenöls
Authors: Ohloff G. , Giersch W. , Schulte‐Elte K. H. , Kovats E. sz.
Published: December 2004

Als einer der Bestandteile des riechenden Prinzips vom bulgarischen Rosenöl wurde (+)‐δ1‐p‐Menthen‐9‐al erkannt. Seine Stereochemie wurde zusammen mit einer Reihe verwandter Verbindungen festgelegt. 2, 8 und 10 besitzen danach die 4 R, 8 R‐Konfiguration, während die Chiralitätszentren der Verbindungen 3, 9 und 11 mit 4 R, 8 S bezeichnet werden müssen. Demzufolge konnte für 4, 5, 12 und 14 die 8 R‐, für 6, 7, 13 und 15 die 8 S‐Konfiguration abgeleitet werden.
Struktur der Marsectobiose. Desoxyzucker, 46. Mitteilung
Authors: Saner A. , Allgeier H.
Published: December 2004

Marsectobiose (1), a disaccharide isolated from Marsdenia erecta R. Br., is shown to be 4‐O‐(3‐O‐methyl‐6‐deoxy‐β‐D‐glucopyranosyl)‐3‐O‐methyl‐2, 6‐dideoxy‐D‐arabinohexose.
Über 1, 5‐Diphenyl‐2, 3, 6, 7‐tetrahydro‐1H, 5H‐pyrazolo[1, 2‐a]pyrazole(2, 6‐Diphenyl‐1, 5‐diazabicyclo[3, 3, 0]octane)
Authors: Wagner‐Jauregg Th. , Zirngibl L. , Demolis A. , Günther H. , Tam S. W.
Published: December 2004

The synthesis of a 1, 5‐diphenyl perhydro‐pyrazolo‐[1, 2‐a] pyrazole (IV) (m. p. = 170–171°) by LiAlH4‐reduction of its 3, 7‐dioxo derivative Va, one of the stereoisomers of V, is described. Va was obtained in small yield by the reaction of cinnamic acid with its hydrazide or with hydrazine. It proved to be identical with the compound obtained previously by interaction of cinnamic acid hydrazide with iodine which in the literature erroneously had been described as N, N′‐dicinnamoyl hydrazine. This hydrazine now was obtained by bis‐acylation of hydrazine with cinnamoyl chloride.

In Va the extremely low NMR. absorption of the tertiary protons at ρ = 4,6 ppm is probably due to the spatial grouping magnified image with the proton situated in the deshielding region of the carbonyl group.

Previously, another tertiary proton with a very low NMR. absorption at ρ = 4,85 ppm has been observed in the «bisimide M», the main criss‐cross addition product of one mole benzaldazine and two moles of N‐(n‐butyl)‐maleinimide. A stereostructure for bisimide M is now proposed, which is a hybrid between those of the bisimides L and H.
Cyclopentadienyl‐Metallverbindungen. 1. Zusammenhang zwischen Stabilität und Dissoziationsenergien von Metall‐Kohlenstoffbindungen in M5H5‐Komplexen
Authors: Egger Kurt W.
Published: December 2004

The existence and thermal stability of CH(3) M(σC5H5) compounds has been viewed in terms of the bond dissociation energies involved, which predict the two‐center covalent two‐electron metal‐σC5H5 bond to be ∼30 kcal/mole less stable than the parent metal‐CH3 bond. The available experimental data are shown to be consistent with this prediction. Electron donating ligands can lead to stable two‐center diene‐type covalent metal‐C5H5 bonds, even where the two‐electron σ‐bond would not be stable. With the exception of group IIB, transition metals are not capable of forming stable metal‐σC5H5 complexes.
Die Hydrolyse des Ga3+‐Ions; potentiometrische Untersuchungen in 3m NaClO4 bei 60°C
Authors: Gamsjäger H. , Aeberhard K. , Schindler P.
Published: December 2004

The hydrolysis of the ion Ga3+ has been investigated at 60°C by potentiometric titrations in a sodium perchlorate medium of the constant ionic strength 3 m. Solutions of various total gallium concentrations B were alkalified by means of a coulometric technique. The concentrations h of the free hydrogen ions were measured with the aid of a glass electrode. From the experimental data, Z, the average number of OH bound per Ga was calculated. The mathematical analysis of the curves Z(logh)B is consistent with the following formulation of the hydrolysis reactions

with log*βl = log k0 kl = −1,7 − 11,55 l.
Kristallstruktur von Cadmium‐Kupfer‐Hydroxidnitrat, CdCu3 (OH)6 (NO3)2·H2O
Authors: Oswald H. R.
Published: December 2004

The crystal structure of cadmium copper hydroxide nitrate, CdCu3 (OH)6 (NO3)2 · H2O, has been determined from three dimensional single crystal X‐ray data.

One single elementary cell of the compound has to be of triclinic symmetry, but as either the crystal is built up from such triclinic domains grown together regularly at angles of 120 degrees, or the nitrate groups of the whole crystal are distributed statistically over three possible orientations standing at 120 degree angles respectively to each other, the structure can also be described in the hexagonal system: a = 6.522 ± 0.005 Å, c = 7.012 ± 0.006 Å, space group D – P 3 m 1, cell content one formula unit.

Mixed layers (00.1) of Cu and Cd atoms are embedded between layers consisting of the OH groups and one oxygen atom per nitrate group. The nitrate groups extend with their trigonal plane nearly perpendicular to the layers (00.1) and connect them by hydrogen bridges between the remaining two oxygen atoms and OH groups of the next layer. The Cd atoms are coordinated octahedrally by six equidistant OH groups, and the Cu atoms have a strongly distorted octahedral (4 + 2) coordination with four OH groups and two nitrate oxygens. Thermogravimetric measurements allowed to distinguish the crystal water molecule from variable amounts of excess water. The hydrogen bonds between OH groups and nitrate oxygen atoms and the deformation of the nitrate groups were confirmed by infrared spectra.
Die Struktur des KNCS‐Komplexes von Nonactin
Authors: Dobler M. , Dunitz J. D. , Kilbourn B. T.
Published: December 2004

The macrotetrolide antibiotic nonactin forms a crystalline complex with KNCS. The crystals are orthorhombic, a = 20.17, b = 15.55, c = 15.33 Å, space group Pnna (D,h) with four molecules per unit cell. The crystal structure has been determined with the help of direct methods and refined by full‐matrix least‐squares analysis of three‐dimensional diffractometer data. The K+ ion is surrounded by four O‐atoms from tetrahydrofurane rings (K+ … O, 2.81–2.88 Å) and by four carbonyl O‐atoms (K+ … O, 2.73–2.81 Å) in approximately cubic 8‐coordination. The observed conformation of the 32‐membered ring of the macrotetrolide has approximate S4(4)‐symmetry and can be described as resembling the seam of a tennis ball with K+ at the centre of the ball and with methyl substituents and methylene groups of the tetrahydrofurane rings on the outside. The constitution and configuration of nonactin, as reported on the basis of chemical studies [10], is confirmed by the present analysis. Some implications of the structure are discussed.
Ungesättigte Zucker. Eine milde Sulfonat‐β‐Eliminierung bei Aminohexopyranosiduronat‐Derivaten
Authors: Kiss J. , Burkhardt F.
Published: December 2004

Substituted 2‐deoxy‐2‐acylamino‐4‐O‐methanesulfonyl‐hexopyranosiduronates yield, by mild alkaline mesylate (a, e)‐β‐elimination, the corresponding 4,5‐unsaturated 4‐deoxyhexopyranosiduronates VIII. This type of aminosugars proved to be the cyclic enol‐ether acetal form of the 2,4‐dideoxy‐2‐acylamino‐hexos‐5‐ulosuronates. The structural principle of the latter can be found e.g. in neuraminic acid.

These 4,5‐unsaturated 4‐deoxy‐acylamino‐hexopyranosiduronates give by reduction with NaBH4 the corresponding 4,5‐unsaturated 2,4‐dideoxy‐2‐acylamino‐hexopyranosides IX (with an endocyclic double bond on the glycosidic C atom 5).

The isomeric 5,6‐unsaturated 2,6‐dideoxy‐2‐acylamino‐hexopyranosides XVI (with an exocyclic double bond) are furthermore synthesized according to the method of HELFERICH [14] by elimination of a molecule of HI from the corresponding 2,6‐dideoxy‐2‐acylamino‐6‐iodo‐4‐O‐acylhexopyranoside derivatives XV.

The ring stability of the two types of isomeric unsaturated hexopyranosides mentioned (bearing respectively an exo‐ and an endocyclic 5‐enol‐ether linkage) has been examined. In accordance with the stability principle of BROWN [16] – on the base of our preliminary experimental indications – the hexopyranosides with endocyclic double bond have been shown to be more stable than those with an exocyclic double bond: the latter (1) decompose slowly at 20°; (2) the α‐glycosidic linkage is very easily split by dil. acetic acid at 20° within a few hours, giving 2, G‐dideoxy‐2‐acyl‐amino‐D‐xylo‐hcxofuranos‐5‐ulose derivatives XX. On the other hand, the hcxopyranosides with endocyclic double bond show in the mass spectrometer, besides other fragmentations, a retro‐dien decomposition.

Some data on the NMR. spectra (100 and 220 MHz) of the above isomeric unsaturated acylamino‐hexopyranosides (and hexopyranosiduronates, resp.) are furnished. The ORD./CD. spectra of the 4,5‐unsaturated 2,4‐dideoxy‐2‐acylamino‐hexopyranosiduronates, which have two «COTTON centres», have been measured.
Recherches sur la formation et la transformation des esters LXXXIII [1]. Réactions de condensation et/ou de phosphorylation, en solution aqueuse, de divers composés organiques à fonctions OH, COOH, NH2, ou autres, à l'aide de polyphosphates linéaires ou cycliques
Authors: Rabinowitz Joseph
Published: December 2004

Amino acids and other derivatives are condensed in aqueous solutions in the presence of linear or cyclic polyphosphates (or other anhydrides of P acids). The best results are obtained in slightly alkaline media (pH 7.5 to 9.5). The reaction, which has been studied at 70°C and at room temperature, proceeds with relative ease even at room temperature. In the case of the cyclic polyphosphates, trimetaphosphate gave the best results as compared with tetra‐ and hexametaphosphate, and among the linear polyphosphates used the yields grew with the average length of the chain.

The significance of this method of condensation as a general method and also in the context of chemical evolution is discussed.

The author suggests that one of the pathways leading to the peptide bond formation involves the intermediate formation of aminoacyl phosphates or polyphosphates by the nucleophilic attack of the carboxylate group of the amino acid on the phosphorus of a linear or cyclic POP bond, giving rise to the labile mixed anhydride, and subsequent nucleophilic attack of the amino nitrogen of a molecule of the amino acid, or of the aminoacyl phosphate already produced, on the C of the mixed anhydride with displacement of phosphate or polyphosphate and formation of a peptide bond. Other pathways may also involve the intermediate formation of phosphoramidates which may result from the reaction of amino groups (or ammonia) with trimetaphosphate in alkaline medium.

Linear and cyclic polyphosphates (which are known to be phosphorylating agents of the OH (alcoholic) function in aqueous solutions at pH's above 7) phosphorylate serine, ethanolamine and threonine in aqueous solutions at pH 8–10 with yields up to 25%.
Strom‐Spannungs‐Zeit‐Beziehungen bei der Bildung metallischer Monoschichten
Authors: Schmidt E.
Published: December 2004

Der bei der Bildung einer Metallmonoschicht fliessende Polarisationsstrom setzt sich aus einem durch die Depolarisatoradsorption bedingten, der zeitlichen Änderung der Oberflächenkonzentration des Mez+‐Ions proportionalen Nettostrom und einem depolarisatorunabhängigen Grundstrom zusammen. Es werden Beziehungen zwischen Nettostrom, Elektrodenpotential und Versuchszeit diskutiert, die sich unter der Annahme quasistatischer, diffusionskontrollierter und diffusions‐durchtritts‐kontrollierter Mez+‐Adsorption ergeben.
Sur quelques réactions par décharge électrique dans les systèmes phosphine‐eau, phosphine‐eau‐ammoniac et phosphine‐eau‐ammoniac‐méthane
Authors: Rabinowitz Joseph
Published: December 2004

Electric discharge reactions in the systems PH3 + H2O, PH3 + H2O + NH3 and PH3 + H2O + NH3 + CH4 have been studied.

In the system PH3 + H2O, they produce polyphosphines (insoluble in water) and hypophosphorous, phosphorous and orthophosphoric acids.

In the system PH3 + H2O + NH3, besides the above products, hypophosphate, pyrophosphate, polyphosphates and possibly polyhyphosphates are also present.

In the system PH3 + H2O + NH3 + CH4, besides all the above inorganic P compounds, organic phosphorus derivatives such as aminoalkyl phosphates and aminoalkanephosphonates are also formed, as well as other non‐phosphorus containing organic products (amino acids, ethanolamine, etc.). The presence of phosphine (or its transformation products), seems to promote condensation reactions in this system since the ratio of amino acids found after hydrolysis (in 6N HCl) to amino acids found before hydrolysis is greater in this system. than in the system (CH4+ H2O+ NH3)iiot containing phosphine.
Contribution à la connaissance des o‐menthols et des o‐menthones (carquéjanols et carquéjanones) ‐ 1ère communication
Authors: Ferretti‐Alloise Maria‐Giulia , Jacot‐Guillarmod André , Naves Yves‐René
Published: December 2004

The mixture of carquejanols obtained from carquejol of carqueja oil has been converted in ketones. The alkohols obtained respectively by hydrogenation on Pt(O2), by lithium‐aluminiumhydride reduction and by Meerwein‐Ponndorf‐Verley reaction have been separated by vapour phase chromatography. The ketones obtained from the Beckmann oxidation of the alkohols has been identified as carquejanone and isocarquejanone by application of the Auwers‐Skita rule.
Die Bildung von Hexahydro‐1,2,4,5‐tetrazinderivaten bei der Reaktion von Aldehyden mit Hydrazin
Authors: Skorianetz W. , Sz. Kováts E.
Published: December 2004

The cristalline reaction products of acetaldehyde and some of its higher straight chain homologues with one equivalent of hydrazine are shown to be 3, 6‐dialkyl‐hexahydro‐1, 2, 4, 5‐tetrazines (1) which can be oxidized to the corresponding 3, 6‐dialkyl‐1, 2, 4, 5‐tetrazines.
Zur Thermodynamik der Metallcarbonate. 4. Mitteilung. Potentiometrische Untersuchungen am System Mn2+CO2H2O
Authors: Gamsjäger H. , Kraft W. , Schindler P.
Published: December 2004

The solubility and the complex equilibria in the system Mn2+‐CO2‐H2O have been investigated at 25°C in solutions of the constant ionic strength 3 M (Na)ClO4. From experimental data the following values for equilibrium constants and Gibbs free energies of formation are deduced:

A predominance area diagram for the system Mn2+‐H2‐CO2(g)‐H2S(g) including MnCO3(ppt.), α‐MnS and Mn2+ is given.
Protonierung von Amino‐ und Hydroxypyrimidinen NMR‐Spektren und Strukturen der Mono‐ und Dikationen
Authors: Wagner R. , Von Philipsborn W.
Published: December 2004

Proton‐NMR. spectra of amino‐ and hydroxypyrimidines including biologically important bases have been measured in four solvents: CF3COOH, CF3COOHSO2, FSO3H and FSO3HSbF5–SO2 at 27° and −55°C. In CF3COOH mono‐cations are formed, whereas in FSO3H and FSO3HSbF5–SO2 double protonation occurs. In each case the structures of the protonated species are derived from the chemical shifts of CH, NH and OH protons and proton‐proton spin coupling constants. A combination of the measurements described leads to a complete assignment of all proton resonances of the protonated pyrimidines. This approach is also recommended for the structural determination of heterocyclic compounds.
Die Photoelektron‐Spektren von Chlor‐, Brom‐ und Jodcyan. Vorläufige Mitteilung
Authors: Heilbronner E. , Hornung V. , Muszkat K. A.
Published: December 2004

The four bands which have been observed in the photoelectron‐spectra of the cyanogen halides CICN, BrCN and ICN (region from 10 to 20 eV) have been assigned to the following states:

.
Über Pyrrolizidinchemie. 9. Mitteilung. Synthese von 1‐Hydroxy‐7‐oxo‐5,6‐dihydropyrrolizin
Authors: Viscontini M. , Bühler H.
Published: December 2004

Das 1, 4‐Dioxa‐7‐azaspiro [4, 4]nonan (I) addiert eine Molekel von α‐Chloracrylsäure‐methylester unter Bildung von 3‐[1, 4‐Dioxa‐7‐azaspiro [4, 4] nonyl‐(7)]‐2‐chlor‐propionsäure‐methylester (II). Dieses Produkt wird mit Polyphosphorsäure zu III deketalysiert, das mit Natriumäthylat zu 1‐Hydroxy‐7‐oxo‐5, 6‐dihydropyrrolizin (IV), unter gleichzeitiger HCl‐Abspaltung, cyclisiert wird. Das unerwartet sehr beständige Produkt wird beschrieben und mit Isomaltol, einem Isologen der Furan‐Reihe, verglichen.
Das Phenylcarbamylchlorid‐Phenylisocyanat‐Gleichgewicht in Chlorbenzol
Authors: Konecny Jan
Published: December 2004

The equilibrium constant for the reaction C6H5NHCOCl = C6H5NCO + HCl in chlorobenzene solution is K = 0.14 mole/kg at 70°. The approximate values of the enthalpy and the entropy of the reaction are ΔH0 = 12 kcal and ΔS0 = 31 cal/deg.
Über Oxidhydroxide des vierwertigen Mangans mit Schichtengitter 2. Mitteilung: Mangan (III)‐manganat (IV)
Authors: Giovanoli R. , Stähli E. , Feitknecht W.
Published: December 2004

The preparation and probable structure of managanese (III)‐manganate (IV) Mn7O13, 5H2O (a0 = 2,84, c0 = 7,27 Å) and manganous (II)‐manganate (IV) Mn7O12, 6H2O are described. Both consist of platelets. Digesting in diluted HNO3 leads to γ‐MnO2 (nsutite). Manganese (III)‐manganate (IV) is much less stable than the sodiummanganese (II, III)‐manganate‐(IV) described earlier and looses water easily when heated or in vacuo. Water loss results in breaking down of the double layer lattice, and the product is only two‐dimensionally ordered, producing only prism reflections on the X ray diagramm. Heating results in a continuous transition to the two‐dimensionally ordered phase, then to a finely divided and very disordered γ‐MnO2, and eventually to a finely divided and disordered β‐MnO2 (pyrolusite). The transition is topotactical so far, but further heating produces δ‐Mn2O3 without obvious topotactical relations to the earlier products. The so‐called ‘δ‐MnO2’ (birnessite) appears to be a family of finely divided and very disordered varieties of such manganates (IV) with part of the Mn3+ substituted by Mn4+. Since such products usually contain remarkable amounts of alkali ions, they are rather varieties of the earlier described sodiummanganese (II, III)‐manganate (IV). A provisional explanation of the streaking in the electron diffractions of these manganate (IV). A provisional explanation of the streaking in the electron diffractions of these manganates (IV) is given. With respect to these results the so‐called ‘δ‐MnO2’ can no longer be attributed to the true manganese dioxides.
Über eine ungewöhnliche Cyclisationsreaktion bei der Umsetzung von (+)‐Epoxy‐α‐dihydrojonon mit Hydrazinhydrat
Authors: Ohloff G. , Uhde G.
Published: December 2004

(+)‐Epoxy‐α‐dihydroionone (2) is formed completely stereospecifically from (+)‐α‐ionone (1). Under the conditions of the Wharton reaction this epoxide gives the expected isomeric allyl alcohols 4 and 5 and, surprisingly, the bicyclic allyl alcohol 3. The structure and absolute configuration of the reaction products have been established. A common intermediate for the formation of compounds 3, 4 and 5 is probably the vinyl anion C.
Synthese und Fragmentierung von 4‐Halogen‐ und 4‐Tosyloxy‐chinuclidinen. Chinuclidinreihe, 9. Mitteilung
Authors: Grob C. A. , Kostka K.
Published: December 2004

The synthesis and fragmentation of 4‐chloro‐, 4‐iodo‐ and 4‐tosyloxy‐quinuclidine are described.
Sur une méthode générale de synthèse des pyridones‐2 condensées
Authors: Eloy F. , Deryckere A.
Published: December 2004

Condensed 2‐pyridones have been prepared by thermal cyclization of vinyl isocyanates substituted in β‐position with aromatic heterocyclic radicals.
Contribution à l'étude de la mésomérie, VIII [1] Système formé de deux atomes à deux électrons et de n atomes à un électron chacun
Authors: Klement O. , Portmann J.
Published: December 2004

Une simplification des calculs dans le cadre de la méthode de mésomérie, analogue à celle indiquée dans [1], est présentée pour un système à deux atomes bivalents et n atomes mono‐valents.
Autoxydation von CuI‐Komplexen IV Der Einfluss der mehrzähnigen Komplexbildner Histamin, Histidin, Carnosin und Histidylhistidin
Authors: Zuberbühler A.
Published: December 2004

The autoxidation of the CuI‐complexes with the chelating ligands histamine, histidine, carnosine, and histidylhistidine has been studied spectrophotometrically using a stopped flow setup. The reaction of these complexes is in general very rapid compared with the reactions of complexes of unidentate ligands studied earlier. It seems that for rapid autoxidation the formation of a CuII‐like quadricoordinated transition state must be easy, and when the same number of similar ligand atoms are bound in the cuprous complex sterical factors seem to play an important role.
Fluxional Isomerism in a Prebullvalene Lactone
Authors: Von Philipsborn W. , Altman J. , Babad E. , Bloomfield J. J. , Ginsburg D. , Rubin M. B.
Published: December 2004

A prebullvalene lactone exhibits fluxional isomerism in solution. Analysis of proton NMR. spectra at 100 MHz and 220 MHz together with variable temperature studies show that the species existing in solution are 7, 8 and 9.
Menthatrienes and the Oxidation of Limonene
Authors: Thomas Alan F. , Bucher Waltraud
Published: December 2004

The oxidation of limonene with mercuric acetate gives a mixture containing mentha‐1. 3. 8‐triene, the hydrocarbon of parsley, and its isomer, mentha‐1. 4. 8‐triene. Selenium dioxide oxidation of limonene in alcohol gives as the main product mentha‐1. 8‐dien‐4‐ol, and pyrolysis of the acetate of the latter, or of mentha‐1. 8‐dien‐10‐yl acetate (the main product of the oxidation of limonene with selenium dioxide in acetic anhydride), also gives a mixture of menthatrienes. A discussion of the selenium dioxide oxidation of limonene is presented.
Synthese von 2‐Methyl‐3‐amino‐inden‐1‐onen
Authors: Allisson S. , Hunziker P. , Lüthi P.
Published: December 2004

2‐methyl‐2, 3‐dibromo‐indan‐1‐ones II reacted with primary or secondary amines yield the corresponding inden‐1‐ones with a basic substituent in position 3 (IV). These compounds possess indicator properties, but are stable over longer periods only as perchlorates.
Zur Stereochemie des (+)‐Davanons
Authors: Ohloff G. , Giersch W.
Published: December 2004

Durch stereospezifische Synthese wird die Konstitution des natürlichen (+)‐Davanons bestätigt und seine Konfiguration mit der des (−)‐Nerolidols verknüpft.
Chimie et pharmacologie de l'apiose II. Synthèse de l'(hydroxyméthyl‐3‐β‐L‐érythrofurannosyl)‐9‐adénine Communication préliminaire
Authors: Tronchet J. M. J. , Tronchet Mme J.
Published: December 2004

A synthesis of the L enantiomer of a very close analog of adenosine is described. Some properties of that compound are compared with those of the D enantiomer of its 3‐epimer which has also been prepared.
Cyclisations par l'intermédiaire de fonctions phénylthioet phénoxy‐carbamoyle. II. Formation d'anhydrides azasucciniques et de leurs produits de polycondensation. Intervention du cation carbamoyle‐pyridinium
Authors: Baudet P. , Otten Cl. , Rao D.
Published: December 2004

The N‐(p‐nitrophenoxy‐carbonyl) derivatives of glycine, DL‐alanine and DL‐leucine are transformed by the action of pyridine into azasuccinic, 3‐methyl‐2‐azasuccinic and 3‐isobutyl‐2‐azasuccinic anhydride, respectively. These cyclisations occur probably via the intermediate N‐carbamoyl‐pyridinium cation magnified image, the rate of cyclisation seems to depend on the concentration of the intermediate in the form of the dipolar ion magnified image, i.e. the ionised carboxyl is necessary for the reaction. In γ‐collidine the cyclisation occurs very slowly; this is attributed to the slowness due to steric hindrance of the production of N‐carbamoyl‐γ‐collidinium cation and its instability.

The azasuccinic anhydrides mentioned polycondense, yielding the corresponding polyglycine, poly‐DL‐alanine and poly‐DL‐leucine. This reaction too is catalysed by pyridine; it can also be effected by γ‐collidine, but the efficacity of the latter in comparison with pyridine is even less than in the catalysis of the cyclisation described above. N‐(p‐nitrophenoxy‐carbonyl)‐glycine reacts with lysozyme in the presence of pyridine; several glycine residues are introduced into the enzyme molecule, the product being insoluble and poorly active.
Synthèse par réaction de Friedel‐Crafts d'analogues partiellement saturés de l'amitriptyline. 1re Communication sur les antidépresseurs et les neuroleptiques tricycliques
Authors: Dostert P. , Kyburz E.
Published: December 2004

It is postulated that one aromatic ring and the amine group in the side chain could be sufficient for the specific fixation of the molecule of a tricyclic antidepressant and for warranting its activity. Some partially saturated derivatives of amitriptyline were prepared, in order to check if pharmacologic activity is retained.
α‐Oximierung von gesättigten Ketonen durch das photochemisch angeregte Nitrit‐Ion
Authors: Pfoertner K.
Published: December 2004

The photochemical behaviour of the nitrite ion must be considered as being similar to that of the carbonyl group. Like the carbonyl group, the nitrite ion in n, π* excitation is capable of abstracting hydrogen atoms from various compounds. During this reaction the nitrite ion is reduced to NO. The radicals obtained by abstracting α‐H atoms from saturated ketones then react with the NO to give nitroso derivatives which undergo a rearrangement to the corresponding oximes ‐ provided that the same carbon bears further hydrogen atoms.

Dimethylformamide and probably also acetylacetone act as quenchers in this photoreaction, whereas aromatic aldehydes and excess NO do not.
Über die Synthese von Verbindungen mit dem Skelett der Homoproaporphine. 7. Mitteilung über natürliche und synthetische Isochinolinderivate
Authors: Schneider Fernand , Bernauer Karl
Published: December 2004

The synthesis of the tetracyclic spiro compounds 11, 12, 13, 14, 17, 18, 19 and 20 with homoproaporphine skeleton is described. Crucial intermediates are the secondary alcohols 10and 16. The structure of the spiro compounds is proved by transformation of 11into the dihydronaphthalene derivative 24 and NMR.‐spectroscopic studies of the latter.
Synthese von zwei Metaboliten des 2,4‐Diamino‐5‐(3,4,5‐tri‐methoxybenzyl)‐pyrimidins (Trimethoprim)
Authors: Rey‐Bellet G. , Reiner R.
Published: December 2004

The synthesis of two metabolites M3 and M4 of 2,4‐diamino‐5‐(3, 4, 5‐trimethoxybenzyl)‐pyrimidine (trimethoprim, 1) is reported. M3 (trimethoprim 1‐oxide) as well as the isomeric 3‐oxide were prepared by oxidation of 1 with m‐chloroperbenzoic acid. The structure of M3 was finally established by x‐ra analysis [4]. The metabolite M4 [2, 4‐diamino‐5‐(3‐hydroxy‐4, 5‐dimethoxy‐benzyl)‐pyrimidine] was prepared by condensation of 3‐benzyloxy‐4, 5‐dimethoxybenzaldehyde (2) with 3‐methoxypropionitrile (3) and guanidine followed by hydrogenolysis of the intermediate 3‐benzyloxy compound 4.
Sur quelques aspects de la polysubstitution de l'amino‐2‐fluorène et de l'acide amino‐2‐fluorène‐sulfonique‐7
Authors: Benz J. , Doré J. , Fleury J.‐P.
Published: December 2004

Electrophilic sulfonation and cyclisation orientation studies were carried out with 2‐aminofluorene and 2‐aminofluorene‐7‐sulfonic acid. Positions 1 and 3 are competing.

A new synthesis of 2‐aminofluorene‐7‐sulfonic acid and the syntheses of derived sulfonamides are described.
Langsame Inversion am pyramidal gebundenen Stickstoff: Konfiguration und Konformation beim Strukturtyp der N, N‐Dialkoxy‐alkylamine aus der Sicht eines semiempirischen MO‐Modells
Authors: Müller K.
Published: December 2004

Nitrogen inversion and rotation around the N‐O single bond in N, N‐dialkoxyalkylamine systems are discussed in terms of a semi‐empirical MO method which is essentially based on the concepts discussed by Mulliken in connection with the “magic formula”. By taking a simplified structural model and adjusting one empirical parameter, a satisfying agreement with experimental results is obtained. The results allow a chemically transparent interpretation and confirm, to a more quantitative extent, the previously discussed concepts [1].

The (spx → p) promotion of the nitrogen lone pair strongly inhibits the inversion process and dominates the simultanous lowering of the σ‐bond energies due to (i) the gain of s‐character in the σ‐involved nitrogen hybrid‐AO's and (ii) the increased σ‐bond overlaps. This dominance is considerably enhanced when electronegative ligands are attached to nitrogen. The total repulsion energy turns out to favour strongly the planar transition state and is essentially determined by the repulsions between the lone pair and the σ‐bonds at nitrogen. Factorization into several repulsive contributions reveals that among these only one inhibits the inversion process, namely the repulsions between the nitrogen lone pair and the bonded and non‐bonded electron pairs on the ligands.

For the process of rotation around the N‐O single bond a potential curve is obtained with two energy minima. The repulsion energy analysis shows that the shape of the potential curve is governed by the repulsions between the lone pairs on oxygen and nitrogen as well as the formally more or less “lone pair‐like” σNC‐bond. This situation is compared to the more general one in which essentially two lone pairs or formally more or less “lone pair‐like” σ‐bonds, on each of two adjacent centers, repel each other by conjugative destabilization; a situation which is realized for instance in molecules that show the anomeric effect.
Addition of a Functionalized Isoprene Unit to an Allyl Alcohol. III. The reaction with optically active cis‐carveol
Authors: Thomas Alan F. , Ohloff G.
Published: December 2004

Provided the temperature is kept under 150°, diene ethers of allyl alcohols rearrange in the double Claisen‐Cope reaction largely by a sigmatropic process in both stages. This was demonstrated by using the 2‐methylbutadienyl ether of (−)‐cis‐carveol, when the product obtained after the two rearrangements was optically active. To check the extent of chirality loss, the same product was synthesized by a route involving only one sigmatropic reaction instead of two. When the reaction occurs at higher temperature, much more chirality is lost, corresponding to the intervention of a diradical process.
Synthese von Ergonin und Ergoptin, zweier Mutterkornalkaloid‐Analoga der Ergoxin‐Gruppe 72. Mitteilung über Mutterkornalkaloide
Authors: Stütz P. , Stadler P. A. , Hofmann A.
Published: December 2004

The syntheses of ergonine and ergoptine, two new analogues of ergot alkaloids possessing the stereochemistry of the already known peptide type alkaloids, are described. The synthetic pathway corresponds to that used already for the synthesis of the natural ergot peptide alkaloids.
Über die Stereochemie der Hydrogenolyse von N‐Benzyl‐Bindungen II. Die Deuteriolyse von chiralem N,N‐Dimethyl‐phenylglycin und die Konfiguration von (+)‐Phenyl‐essigsäure‐2‐d1
Authors: Dahn H. , O'Murchu C.
Published: December 2004

The steric course of the hydrogenolytic cleavage of benzyl‐N‐bonds using Pd‐C catalyst was determined by deuteriolysis of R(−)‐N,N‐dimethyl‐phenylglycine I, which gave (+)‐phenylacetic acid containing 70% of the monodeutero compound. The configuration of (+)‐phenylacetic acid‐2‐d1 was determined (S) and its optical purity estimated by Schmidt degradation to chiral S(+)‐benzylamine‐α‐d1. On the basis of these results, hydrogenolysis of I can be evaluated to proceed by 80% inversion and 20% retention of configuration. Methyl N,N‐dimethyl‐phenyl‐glycinate yielded racemized methyl phenylacetate‐2‐d1.
Neuartige Isomeriefälle bei 1:2‐CrIII‐ und CoIII‐Komplexen von o, o'‐Dihydroxyazoverbindungen: Pyramidal gebundener Stickstoff mit hoher Inversionsbarriere?
Authors: Schetty G.
Published: December 2004

From the dimensions described in previously known X‐ray structure analyses and from NMR.‐spectroscopical datas of a 1:2 CoIII complex it is concluded that metal chelates of two and tri‐dentated azo compounds are present in the diketo or quinone mono hydrazone form, provided that such a form is possible. As the metal atoms replaces the hydrazone proton the coordinating nitrogen atom can be predetermined.

For the first time in the case of 1:2 Cr complexes from o,o'‐dihydroxy azo compounds small amounts of byproducts have been observed which have the empirical composition of the main complexes. As the coordinated nitrogen atom is sp3‐hybridized, its three bonds should be arranged in a pyramidal form. Therefore the ligands should be slightly bent. In the 1:2 Cr complexes where two of these ligands are coordinated to the metal atom perpendicularly to each other (Drew‐Pfitzner‐arrangement) 3 conformers (+ 3 mirror images) are possible. These conformers are ascribed to one group of the observed isomeric complexes. For another group it is supposed that at least one ligand is coordinated in the plane azo form.

The postulated thrice bonded nitrogen atom possesses the requirements for a high inversion barrier: it is a member of two ortho condensed rings; moreover, it is bound to a Lewis acid.

No such system seems to have been described, but in some published X‐ray structure analyses, there is evidence to be found of its existence.
études sur les composés organométalliques IX. étude spectrophotométrique de quelques complexes du tétrachlorure de titane avec des di‐ et triamines tertiaires
Authors: Tabacchi R. , Vuitel L. , Jacot‐Guillarmod A.
Published: December 2004

The complexes of TiCl4 with various tertiary di‐ and triamines are studied by using IR, spectroscopy. Assignments for the observed frequencies are proposed.
Electronenstruktur und physikalisch‐chemische Eigenschaften von Azo‐Verbindungen, Teil XV. Über die Struktur der protonierten Azobrücke in Azobenzolderivaten
Authors: Haselbach E.
Published: December 2004

The pKa‐values of a number of para‐ and ortho‐substituted azobenzenes have been measured. The effects of the substituents have been parametrized using a modified Hammett‐equation. The results support the classical view that protonation of the azo‐bridge takes place on a distinct N‐atom with formation of a N‐H σ‐bond.
Kernresonanz‐spektroskopische Untersuchung protonierter Stickstoffverbindungen in Trifluoressigsäure
Authors: Giger W. , Simon W.
Published: December 2004

The nuclear magnetic resonance spectra of a series of protonated organic nitrogen compounds in trifluoroacetic acid solution have been studied. A direct correlation between the exchange rate of the ammonium protons and the acidity constant of the functional group is established. Substituted anilinium and pyridinium ions with pK values below 4 show coalescence for the signals of N⊕H protons and disappearence of the coupling with the α protons.
Hetero‐“Tickling” am A3X‐System von 13CH312CN, eine Bestimmungsmethode hoher Genauigkeit von Methylkohlenstoffverschiebungen
Authors: Wehrli F. W. , Simon W.
Published: December 2004

Heteronuclear spin tickling experiments in the degenerate A3X spin system of a 13CH3 group have proved to be suitable for accurate carbon shift determinations in methyl groups. A weak perturbation of one of the 13C quadruplet lines splits both proton doublet lines into a sub‐triplet with the relative signal strengths depending on whether an outer or inner 13C line is irradiated. Deviation from exact resonance with one of the 13C transitions modifies the relative intensities, and finally further splitting of the outer subtriplet lines occurs in accordance with theory. The amount of this additional splitting is equal to the difference between the double resonance frequency and the 13C transition frequency to be measured. Signal distortions observed when the double resonance spectra are recorded in the INDOR sweep mode have to be ascribed to the fact that the tickling effect competes with the generation of transient nutations.
Die Glykoside der Wurzeln von Xysmalobium dilatatum WEIMARCK. 1. Mitteilung: Isolierungen. Glykoside und Aglykone, 327. Mitteilung
Authors: Meister L. , Kaufmann H. , Stöcklin W. , Reichstein T.
Published: December 2004

The roots of Xysmalobium dilatatum Weimarck contain uzarin and xysmalorin as major glycosides. The same two compounds are also present as main components in the glycoside mixture from the roots of Xysmalobium undulatum. In addition to that, X. dilatatum also contains appreciable amounts of pregnane derivatives, linked to 2‐deoxy‐sugars. Four such xanthydrolpositive compounds (the dilatoides A, B, C and D) have been isolated in amorphous but pure or nearly pure form; they have not been detected in the roots of X. undulatum.
Photoelektron‐Spektren von Cycloalkenen und Cycloalkadienen. Vorläufige Mitteilung
Authors: Bischof P. , Heilbronner E.
Published: December 2004

The photoelectron spectra of cis‐cycloalkenes (with three to ten carbon atoms in the ring), of three isomeric, non‐conjugated cyclodecadienes, and of cis, cis, ‐1, 3‐cycloalkadienes (with five to eight carbon atoms in the ring) have been recorded. The essential features of their π‐bands and of the first σ‐bands are briefly discussed.
Alkalikationen‐Spezifität und Träger‐Eigenschaften der Antibiotica Nigericin und Monensin
Authors: Lutz W. K. , Wipf H.‐K. , Simon W.
Published: December 2004

It is shown by means of IR. spectroscopic methods that nigericin and monensin have a cyclic conformation similar to that of their silver salts. Complex formation constants with sodium and potassium ions follow the selectivity order determined by EMF. measurements on liquid membranes: nigericin: K+ > Rb+ > Na+ > Cs+ > Li+; monensin: Na+ > K+ > Li+ > Rb+ > Cs+. Transport experiments show that nigericin and monensin facilitate the diffusion of potassiumions across model membranes, although in electrolytic transport experiments the permeability is not affected.
Photochemical Reactions. Part 60 [1]. The photorearrangement of a 2, 5‐diene‐1, 7‐dione
Authors: Domb S. , Schaffner K.
Published: December 2004

The 2, 5‐diene‐1, 7‐dione 12 rearranges photochemically to the cyclopentenonyl‐cyclopropyl ketone 13. Dienone 12 does not emit phosphorescence at 78K. Sensitization and quenching experiments indicate that the photorearrangement occurs in an excited triplet state with ET between ca. 61–65 kcal/mol according to sensitization data, and between ca. 54–58 kcal/mol according to quenching results. By comparison, the 2, 5‐dienone 1 behaves similarly with respect to sensitization and quenching of its photorearrangement [3] (indicating ET < 61 and ca. 54–58 kcal/mol, respectively) and to its lack of phosphorescence, while the 2‐ene‐1, 5‐dione 8 emits phosphorescence (ET = 72.4 kcal/mol) and sensitization, and quenching data indicate ET between ca. 68–72 and >61 kcal/mol for its photorearrangement, respectively. It is concluded that the triplet energy of the reactive state of compound 12 extends either over the two enone groups involving strong interaction or is localized on the ring A enone only.

Photoproduct 13 rearranges further to the stereoisomer 14 on direct excitation and sensitization with acetophenone. Thioxanthone as triplet sensitizer and naphthalene as triplet quencher are ineffective. The reverse isomerization process, i.e. 14 → 13, is not observed.
Die Struktur des Antibioticums Roridin H. Verrucarine und Roridine, 20. Mitt. [1]
Authors: Traxler P. , Tamm Ch.
Published: December 2004

Structure 1 has been established for roridin H (C29H36O8), an antibiotic isolated from Myrothecium verrucaria and formerly namend verrucarin H [3]. Base catalysed hydrolysis of 1 gave the known terpene alcohol verrucarol (8; C15H22O4) and myrothecinic acid (3; C14H18O6), a previously undescribed dicarboxylic acid. The structure of 3 was determined by spectral methods and by chemical cleavage of the unusual acetal group of dimethyl hexahydromyrothecinoate (6) by hydrolysis with HCl in the presence of 2, 4‐dinitrophenylhydrazine, producing the 2, 4‐dinitrophenylhydrazone 13 of 3‐methylglutaric acid semialdehyde 10 and methyl 6, 7‐dihydroxy‐octanoate (11). 13 was transformed in to dimethyl 3‐methylglutarate (15). Cleavage of 11 with HIO4 gave acetaldehyde and adipic acid semialdehyde (17) which was oxidized to adipic acid (19). The 220 MHz NMR spectra of roridin H (1) and dimethyl hexahydromyrothecinoate (6) allowed unequivocal assignment of the signals to the majority of the protons in the antibiotic.