bluuebunny/crossref_metadata_2025_split huggingface dataset:
Der 2‐Trimethylsilyläthyl‐Rest als selektiv abspaltbare Carboxy‐Schutzgruppe
Authors: Sieber Peter 
Published: December 2004

The 2‐trimethylsilylethyl residue, a selectively cleavable carboxyl protecting groupIn a search for new carboxyl protecting groups suitable for use in peptide synthesis, 2‐trimethylsilylethyl esters [‐COOCH2CH2Si(CH3)3] of several N‐protected amino acids have been prepared. These esters can be synthesized in good yields from Na‐benzyloxycarbonyl‐amino acids and 2‐trimethylsilylethanol with dicyclohexylcarbodiimide in the presence of pyridine. They are stable under a wide variety of conditions used during coupling and work‐up in peptide synthesis. For removal the 2‐trimethylsilylethyl group is readily cleaved by fluoride ions, preverably using a quaternary ammonium fluoride in dimethylformamide. Some side reactions which occurred during the removal of the 2‐trimethylsilylethyl group are discussed.Special attention has been paid to the question of racemization during the treatment with fluoride ions. No. evidence of racemization was found in any of the cases examined.
Transition metal complexes with bidentate ligands spanning trans‐positions. IV. Preparation and properties of some rhodium and iridium complexes of 2,11‐bis(diphenylphosphinomethyl)benzo [c]phenanthrene
Authors: Reed Frank J. S. , Venanzi Luigi M. 
Published: December 2004

AbstractThe bidentate phosphine 2,11‐bis(diphenylphosphinomethyl)benzo [c]phenanthrene (1) has been used to prepare the mononuclear, square planar complexes trans‐[MX(CO)(1)] and trans‐[M(CO)(CH3CN)(1)][BF4] (M = Rh, Ir; X = Cl, Br, I, NCS). It is found that the tendency of these complexes to form adducts with CO, O2 and SO2 is significantly lower than that of the corresponding Ph3P complexes. The oxidative‐addition reactions of complexes trans‐[IrX (CO) (1)] with hydrogen halides give the six‐coordinate species [IrHX2(CO) (1)]. The complexes [IrH2I (CO) (1)] and [IrH2L (CO) (1)] [BF4] (L = CO and CH3CN) have been obtained from hydrogen and the corresponding substrates. The model compounds trans‐[MCl (CO) (Ph2PCH2Ph)2] (M = Rh, Ir), trans‐[Ir (CO) (CH3CN) (Ph2PCH2Ph)2] [BF4], [IrHCl2(CO)(Ph2PCH2Ph)2] and [IrH2(CO)2(Ph2PCH2Ph)2] [BF4] have been prepared and their special parameters are compared with those of the corresponding complexes of ligand 1. The influence of the static requirements of this ligand on the chemistry of its rhodium and iridium complexes is discussed.
Synthesis of 1‐ and 5‐Aryl‐2,4‐benzothiazepines. 25th Communication on Seven‐membered Heterocycles
Authors: Bream John B. , Schmutz Jean 
Published: December 2004

Abstractα‐Aryl‐o‐xylyl dibromides 1 reacted with thioureas to give the mono‐isothiouronium salts 2, bis‐isothiouronium salts 4 being formed as by‐products in some cases. Compounds 2, which readily reacted with water or alcohols to form 3, were cyclized with Na2CO3 in anhydrous acetone to yield 5‐aryl‐2,4‐benzothiazepines 5, 6 and 7, but the 2′‐chlorophenyl‐derivative 21 exceptionally cyclized to the cyclobutene 20. The 1‐aryl‐2,4‐benzothiazepines 14, 15 and 16 were prepared unequivocally by acid‐catalysed cyclizations of thioureas 13 and 19.
Crystal and Molecular Structure of trans‐[(2‐chlorophenyl)‐1‐benzocyclobutenyl]‐1,4,5,6‐tetrahydro‐ 2‐pyrimidyl‐sulfide
Authors: Weber Hans Peter , Petcher Trevor J. , Loosli Hans Rudolf 
Published: December 2004

Kristalline und molekulare Struktur von trans‐[(2‐chlorphenyl)‐1‐benzocyclobutenyl]‐(1,4,5,6‐tetrahydro‐ pyrimidyl)‐sulfid.Zur Abklärung von Konstitution und Konfiguration der Titelverbindung wurde eine Röntgenstrukturanalyse durchgeführt. Die Kristalle gehören zur monoklinen Raumgruppe C2/c, a = 17.221 (6), b = 7.846 (2), c = 25.031 (8) Å, β = 104.55 (2)°, Z = 8. Die Struktur wurde mit 2188 signifikanten Daten bis R = 0.055 verfeinert. Die mittlere Standardabweichung der Lagekoordinaten der C‐ und N‐Atome beträgt 0.003 Å.
Chemical selectivities disguised by mass diffusion. IV. Mixing‐disguised nitrations of aromatic compounds with nitronium salts. 4th communication on the selectivity of chemical processes
Authors: Nabholz Felix , Rys Paul 
Published: December 2004

AbstractThe disguise of the intrinsic selectivity of competitive, consecutive reaction systems by the mixing process is demonstrated experimentally using the fast nitration of a number of aromatic compounds with nitronium salts in nitromethane. The measured product distributions were compared with the distributions predicted from our mixing‐reaction model developed previously [2] [4]. This comparison enabled the relative intrinsic rate constants for the second nitration step of the aromatic compounds investigated to be determined.
Trimers of Aliphatic Monosubstituted Ketenes from Acid Chlorides
Authors: Osman Maged A. , Seibl Josef , Pretsch Erone 
Published: December 2004

AbstractA new synthesis of trimers of aliphatic monosubstituted ketenes from acid chlorides is described. The structures of the products are shown to be alkyl substituted γ‐hydroxy‐α‐pyrones by NMR. and mass spectroscopy. 13C‐NMR. studies indicate, that an acetanilide/aluminium‐chloride complex catalyses the formation of the products.
Thermisch und photochemisch induzierte intramolekulare, 1,3‐dipolare Cycloadditionen von 5‐(2‐Allyloxyphenyl)‐2‐phenyltetrazol. Vorläufige Mitteilung. 54 Mitteilung über Photoreaktionen
Authors: Meier Hansruedi 
Published: December 2004

Thermal and Photochemically Induced Interamolecular 1,3‐Dipolar Cycloaddition Reactions of 5‐(2‐Allyloxyphenyl)‐2‐phenyltetrazoleThe title compound 5 is easily obtained by a recently described procedure (Scheme 2). The tetrazole 5 reacts at 165–170° or on irradiation at room temperature to yield 2‐phenyl‐3,3a‐dihydrochromano[4,3‐c]pyrazole (7, Scheme 3), which probably arises by intramolecular [3+2]‐cycloaddition of the intermediate nitrilimine. Dehydrogenation of 7 with chloranil leads to 2‐phenylchromano[4,3‐c]pyrazole (8, Scheme 3).
Stickstoffhaltige Dieisen‐hexacarbonyl‐Komplexe aus 3‐Phenyl‐2H‐azirinen
Authors: Nakamura Yushin , Bachmann Kurt , Heimgartner Heinz , Schmid Hans , Daly John J. 
Published: December 2004

Nitrogen‐containing diiron‐hexacarbonyl complexes from 3‐phenyl‐2H‐azirinesReaction of 2,2‐dimethyl‐3‐phenyl‐2H‐azirine (1) with diiron‐enneacarbonyl yields as an insertion product, and in addition to other products, the diiron‐hexacarbonyl complex 2 (Scheme 1), whose structure was derived from spectral data, in particular 13C‐NMR.‐data (Table 1). With trimethylamine oxide in benzene, 2 is converted into the urea derivative 3, and yields with cerium (IV) ammonium nitrate the nitrate 4 (Scheme 1). The analogous complexes 6 and 9 have been obtained by irradiation of 1‐phenyl‐vinyl azide (5) and ironpentacarbonyl (Scheme 1) and from vinyl isocyanate (8) and diiron‐enneacarbonyl at 40° (Scheme 2), respectively.The azirine 1, an acetylenic compound and diiron‐enneacarbonyl in benzene react to give complexes of type 10 as the main product (Scheme 3). The structure of complex 10 has been established by X‐ray single crystals analysis. On the 13C‐NMR. time scale the carbonyl groups of compound 10 show a fluxional behaviour: below −50° the CO‐groups of one of the two Fe(CO)3‐groups undergo intranuclear exchange, above −50° the CO‐groups of both Fe(CO)3‐groups undergo intranuclear exchange.Tentative reaction mechanisms for the formation of the complexes of type 2 and 10 are formulated in Schemes 5, 6 and 7.
Tieftemperatur‐Photochemie von 2‐Alkyl‐indazolen
Authors: Heinzelmann Willy 
Published: December 2004

Photochemistry of 2‐Alkyl‐indazoles at Low Temperatures2‐Alkyl‐indazoles 1 undergo a variety of photoreactions (Scheme 1) which have been shown to proceed via excited singlet states of the neutral and protonated indazole, respectively [6]. The quantum yields of these reactions decrease with decreasing temperature; around 150°K the 2‐alkyl‐indazoles are practically reactivity of both neutral and protonated indazoles is observed (Fig. 3), yielding 2‐amino‐acylbenzenes 7, obviously formed by hydrolysis of the corresponding imines 6 (Scheme 2). Yellow ‘intermediates’ (Figs. 1 and 2) which are observable only at low temperatures upon irradiation of neutral indazoles but are rather stable even at room temperature in acid solutions, could be identified as quinoid tautomers 8 of the imines (Scheme 4). It is assumed that the formation of the imines 6 proceeds via an arylnitrene or arylnitrenium‐ion 13 (Scheme 5) and subsequent hydrogen abstraction, the nitrenes being formed directly in their triplet ground‐state from the triplet state of the indazoles.
Photochemische Reaktionen. 95. Mitteilung. Zur Photochemie konjugierter Epoxy‐enone: Die UV.‐Bestrahlung von 9‐Isopropyl‐6‐methyl‐9, 10‐epoxybicyclo [4.4.0] dec‐1‐en‐3‐on
Authors: Dey Ashesh Kumar , Wolf Hans Richard 
Published: December 2004

The Photochemistry of Conjugated Epoxy‐enones: Photolysis of 9‐Isopropyl‐6‐methyl‐9,10‐epoxybicyclo [4.4.0]dec‐l‐en‐3‐onThe title compound 1 undergoes on π, π*‐excitation vinylogous β‐cleavage of the C(γ), O‐bond and isomerizes to the unsaturated 1, 5‐diketone8(58%) and the tricyclic diketone9 (14%). On n, π*‐excitation, however, 1 undergoes only desoxygenation to the dienone 7 (ca. 15%) besides polymerization. UV.‐irradiation of 1 (λ ≥ 347 nm) in the presence of tributyl‐stannane gives 7 in 85% yield; in the presence of tributylstannane‐d1 1 yields 13, the deuterated analogon of 7 (85% yield; d1 ca. 50%); 7 has been proven to be stable on π, π* ‐ as well as on n, π*‐excitation.
Reduction of 5,6‐Dimethylidene‐exo‐2,3‐epoxynorbornane with Metal Hydrides. Efficient syntheses of 6‐methyl‐5‐methylidene‐anti‐3‐ nortricyclanol and of 2,3‐dimethylidene‐anti‐7‐norbornanol
Authors: Chollet André , Vogel Pierre 
Published: December 2004

Abstract5,6‐Dimethylidene‐exo‐2,3‐epoxynorbornane (1) is reduced slowly by LiAlH4 in boiling tetrahydrofuran (THF) and furnishes a mixture of 5,6‐dimethylidene‐exo‐2‐norbornanol (2), 2,3‐dimethylidene‐anti‐7‐norbornanol (3) and principally 6‐methyl‐5‐methylidene‐anti‐3‐nortricyclanol (4). The yield of 4 is the highest for low initial concentrations of LiAlH4; it decreases in favour of alcohols 2 and 3 at high concentration of LiAlH4. The reduction of 1 with AlH3 in THF yields 3 as the major product, thus revealing an efficient synthesis of 7‐substituted‐2, 3‐dimethyl‐idenenorbornane derivatives. No alcohol 2could be isolated by LiEt3BH reduction of 1. LiAlD4 reduces 1 into the monodeuterated alcohols 2‐d, 3‐d and 4‐d. The deuterium label is found in the endo‐position at C (3) in 2‐d, in the exo‐position at C(5) in 3‐d and in the methyl group of the tricyclic alcohol 4‐d. Mechanistic limits for the formation of 2, 3 and 4 are discussed briefly.
Vibrational Spectra of Anhydrous Lanthanum, Europium, Gadolinium, and Dysprosium Nitrates and Oxinitrates
Authors: Bünzli Jean‐Claude G. , Moret Etienne , Yersin Jean‐Robert 
Published: December 2004

AbstractIR. and Raman spectra of LnONO3 (50–4,000 cm−1, LnLa, Gd, Eu, and Dy) are reported and discussed. The low frequency region of the spectra reflects the cubic structure of these compounds. The dimensions of the cubic unit cells determined by X‐Ray powder diagrams are: 12.81 ± 0.05 Å for EuONO3, 12.69 ± 0.05 Å for GdONO3, and 12.67 ± 0.05 Å for DyONO3. The vibrational frequencies of the nitrato group are consistent with a bidentate nitrate of C2v symmetry. The synthesis of anhydrous Ln (NO3)3 (LnLa, Gd, Eu, and Dy) by dehydration of the corresponding penta‐ or hexahydrates is described. The IR. and Raman spectra (50‐4,000 cm−1) are analysed. Splitting of the bands point to a complex structure of these compounds. All six vibrational modes of the nitrato group are observed and the data are again consistent with bidentate NO−3 moieties. Finally, an analytical control of the purity of Ln (NO3)3 is suggested.
Synthese und Chiralität von (5S, 6R)‐5,6‐Epoxy‐5,6‐dihydro‐β,β‐carotin und (5R, 6R)‐5,6‐Dihydro‐β,β‐carotin‐5,6‐diol, einem Carotinoid mit ungewöhnlichen Eigenschaften
Authors: Eschenmoser Walter , Eugster Conrad Hans 
Published: December 2004

Synthesis and Chirality of (5S,6R)‐5,6‐Epoxy‐5,6‐dihydro‐β,β‐carotene and (5R,6R)‐5,6‐Dihydro‐β,β‐carotene‐5,6‐diol, a Compound with Unexpected Solubility CharacteristicsWittig‐condensation of azafrinal (1e) with the phosphorane derived from 7 leads to a (1:3)‐mixture of (E)‐9′‐ and (Z)‐9′‐β,β‐carotene‐diol 3, from which pure and optically active 3 ((5R,6R)‐5,6‐dihydro‐β,β‐carotene‐5,6‐diol) has been isolated as bright violet leaflets, m.p. 168°. Due to the trans‐configuration of the diol moiety and to severe steric hindrance, hydrogen bonding is reduced to such an extent, that 3 behaves much more as a hydrocarbon than as a diol. There is good evidence that the so‐called ‘β‐oxycarotin’ obtained by Kuhn & Brockmann [15] by chromic acid oxidation of β, β‐carotene is the corresponding racemic cis‐diol. 3 has been converted into (5S, 6R)‐5,6‐epoxy‐5.6‐dihydro‐β,β‐carotene (4), m.p. 156°. This transformation establishes for the first time the chirality of a caroteneepoxide (without other O‐functions).Full spectral and chiroptical data including a complete assignement of 13C‐chemical shifts for azafrin methyl ester and 3 are presented.
Studies on the Synthesis of (2R,4′R,8′R)‐α‐Tocopherol Alternative Syntheses of 2‐Chroman‐acetic Acid Intermediates
Authors: Cohen Noal , Scott John W. , Bizzaro Fred T. , Lopresti Rocco J. , Eichel Wayne F. , Saucy Gabriel , Mayer Hans 
Published: December 2004

AbstractAs an extension of previous studies on the total synthesis of (2R,4′R,8′R)‐α‐tocopherol (1) [1] [2], (S)‐(−)‐2‐(6‐benzyloxy‐2,5,7,8‐tetramethylchroman)acetic acid (6), a pivotal intermediate, possessing the absolute configuration required for construction of 1 was prepared by optical resolution of the racemic modification 11. the latter substance was obtained by two routes, one emanating from the hydroxy acetal 7 [1] and the other based upon the Lewis acid mediated cycloaddition of trimethylhydroquinone to rac.‐3‐hydroxy‐3‐methylpent‐4‐en‐l‐yl acetate (16) giving rac. ethyl 2‐(6‐hydroxy‐2,5,7,8‐tetramethyl‐chroman)acetate (12).
Drüsenfarbstoffe aus Labiaten: Strukturen von 16 Diterpenen (Coleone und Royleanone) aus Coleus coerulescensGÜRKE
Authors: Grob Konrad , Rüedi Peter , Eugster Conrad Hans 
Published: December 2004

Leaf‐gland pigments from labiatae: structures of 16 diterpenoids (coleons and royleanones) from Coleus coerulescens GÜRKEThe Abyssinian labiate Coleus coerulescens has been investigated for its leaf‐gland pigments. From the very complex mixture of abietanoic diterpenoids the following pure constituents were isolated and their structures established:
Diosphenols: coleon C (1a), 16‐O‐acetyl‐coleon C (1b), coleon W (1f);
A/B‐trans‐6, 7‐diketones: coleon D (2b), 16‐O‐acetyl‐coleon D (2c), coleon V (2a);
Spiro‐coleons: 7,12‐bis(O‐desacetyl)‐coleon N(3a), 12‐O‐desacetyl‐coleon N (3b), coleon O (4), 6,12‐bis (O‐desacetyl)‐coleon R (5a), 12‐O‐desacetyl‐coleon R (5b), 3‐O‐desacetyl‐3‐O‐formyl‐coleon Y (5g);
Royleanones: The abeo‐compounds 6a, 6b, and 7.

Main compounds are 3b, 5e and 5g. This is the first record of a co‐occurrence of diosphenols, 6,7‐dioxo‐coleons, spiro‐coleons and royleanones. Preliminary experiments show that solvolytic opening of the cyclopropane‐ring followed by tautomerisation, oxidation to hydroxy‐p‐benzoquinones or elimination to quinomethanes and subsequent nucleophilic attack of the solvent leads to compounds with a 2′‐substituted propyl group at C(13), thus supporting the biosynthesis of the unusual coleon E side chain.
Structural Requirements for the Enzymatic Deamination of Cytosine Nucleosides
Authors: Kreis W. , Watanabe K. A. , Fox J. J. 
Published: December 2004

AbstractThirty‐three 1‐β‐D‐pentofuranosylcytosine nucleosides were examined as substrates of crude cytidine deaminase from mouse kidney. In addition to previous observations of structural features in substrates required for enzymatic deamination [e.g., a free 3′‐hydroxyl in the ‘down’ ribo (arabino)configuration] we find that: modification of the aglycon by substitution of a fluorine atom at C(5) results in a several‐fold increase in the deamination velocity relative to cytidine whereas insertion of a methyl group at C(5) decreases the deamination velocity. This decrease is even more pronounced when a methyl group is substituted at C(6).Though xylosylcytosine and 3′‐deoxy‐3′‐fluoro‐xylo‐C are not substrates for this deaminase, those xylofuranosylcytosines bearing good leaving groups (e.g., bromo, mesyloxy, or tosyloxy) at C(3′) are deaminated with substantial deamination velocities. This is probably due to a prior chemical reaction leading to arabino nucleosides bearing a free ‘down’ 3′‐hydroxyl.A different situation is obtained with arabino nucleosides. Though ara‐C and 2′‐deoxy‐2′‐fluoro‐ara‐C are substrates for this deaminase, substitution of bulky groups (e.g., chloro, bromo, or mesyloxy) at C(2′) substantially decreases the susceptibility to deamination. An hypothesis is offered to explain these differences between xylo‐and arabino‐cytosines.The presence of a free hydroxyl group at position 5′ is not essential for enzymatic deamination.
Vergleichende Untersuchung von Reaktivitäten und Ionenstrukturen beim monomolekularen Abbau isomerer Hydroxyzimtsäuremethylester unter Elektronenbeschuss
Authors: Kuster Thomas , Mändli Hugo , Robbiani Richard , Seibl Josef 
Published: December 2004

Comparative investigation of reactivities and ion structures upon electron impact induced degradations of the isomeric hydroxy cinnamic acid methyl estersBy analysis of energy release data in metastable peaks it is shown that m‐ and p‐hydroxy cinnamic acid methylesters retain specific structural features upon degradation under electron impact, although their spectra are very similar and the shapes of the metastable peaks due to the initial methoxy cleavage are identical. A pronounced charge radical localization in the molecular ion is indicated. The o‐isomer is found to yield a coumarin type structure by elimination of methanol, whose further degradation by decarbonylation involves at least three different mechanisms. The resulting ion structures are different from benzofuran.
Umamidierungsreaktionen an offenkettigen Amino‐amid‐Systemen. 1. Mitteilung über Umamidierungsreaktionen
Authors: Guggisberg Armin , Dabrowski Boleslaw , Kramer Urs , Heidelberger Christian , Hesse Manfred , Schmid Hans 
Published: December 2004

Transamidation Reaction of Open Chaine Amino‐amidesAmino‐amides of type 11 with a primary amino and a N, N‐disubstituted amide group isomerize under base catalysis completely to amino‐amides 16 with a secondary amino and a N‐monosubstituted amide group (see Scheme 3). Amino‐amides having a secondary instead of the primary amino group are under base catalysis in equilibrium with the corresponding isomeres (Scheme 4). The opening of the proposed tetrahedral intermediate 13 (Scheme 3) takes place under stereo‐electronic control (Schemes 5 and 6).
Umamidierungsreaktionen an cyclischen Amino‐amid‐Systemen. 3. Mitteilung über Umamidierungsreaktionen
Authors: Guggisberg Armin , Kramer Urs , Heidelberger Christian , Charubala Ramamurty , Stephanou Euripides , Hesse Manfred , Schmid Hans 
Published: December 2004

Transamidation Reactions with Cyclic Amino‐amidesLactames which are substituted at the nitrogen atom by a 3‐aminopropyl residue are transformed under base catalysis to cyclic amino‐amides enlarged by 4 ring atoms. The formed ring must be at minimum 12‐membered. Scheme 2 illustrates this result: the 8‐membered 7 is transamidated in 96% yield to the 12‐membered ring 8 (in the presence of potassium 3‐aminopropylamid in 1, 3‐propanediamine), the 9‐membered 10 to the 13‐membered ring 11 (97%) and the 11‐membered 14 to the 15‐membered ring 15. Furthermore, the 13‐membered ring 27 (Scheme 5) is transformed to the 17‐membered 28. In the case of the 15‐membered lactame 15 it is demonstrated that 14 is not formed back under the conditions of the transamidation.Large ring lactames which are substituted at the nitrogen atom by a 3‐(alkylamino) propyl group lead under base catalysis to an equilibrium mixture, e.g. the 17‐membered 26 is in equilibrium with the 21‐membered 29. This result is similar to the behavior of the corresponding open‐chain amino‐amides [2].Because of transannular interactions, the 11‐membered ring 2 is not stable: transamidation of the 7‐membered 1 (Scheme 1) doesn't give the expected 2, but its water elimination product 3 in small yield. The N‐tosyl derivative of 2, namely 20, is synthesized by an independent route (Scheme 3). Detosylation of 20 yields the 7‐membered 1 instead of 2. Concerning the mechanism of this interesting reaction see Scheme 4.
Kristallstruktur eines überbrückten 1,2,3‐Oxadiazolidin‐5‐ons
Authors: Bieri Jost H. , Meier Hansruedi , Heimgartner Heinz 
Published: December 2004

The Crystal Structure of a Bridged 1,2,3‐Oxadiazolidin‐5‐one Derivative3‐(2‐Allylphenyl)‐4‐phenylsydnone (1) undergoes in solution an intramolecular, 1,3‐dipolar cycloaddition reaction to give 2‐oxo‐1‐phenyl‐1,5‐methano‐1,2,4,5,6,11‐hexahydro [1,2,3] oxadiazolo [3,2‐a] cinnoline (2). The unique 1,2,3‐oxadiazolidin‐5‐one structure of this molecule has been proved by X‐ray analysis. The crystal structure has been solved by direct methods and refined by full‐matrix least squares calculations to R = 0,046. The crystal system is orthorhombic, space group Pbca, with unit cell dimensions a = 10,546, b = 15,482, c = 16,531 Å.
An Efficient Stereoselective Synthesis of (±)‐Sweroside and (±)‐secologanin aglucone O‐methyl ethers. Preliminary communication
Authors: Hutchinson C. Richard , Mattes Kenneth C. , Nakane Masami , Partridge John J. , Uskoković Milan R. 
Published: December 2004

AbstractA seven‐step stereoselective synthesis of (±)‐sweroside aglucone O‐methyl ether (16a) was achieved in 27% overall yield from 1, 4‐cyclohexadiene (4) and methyl diformylacetate (5). Secologanin aglucone O‐methyl ether (18a) was then formed from 16a in 90% overall yield by a straightforward process. The key step in the synthesis was a [2+2]‐enone‐photoannelation of 4 and 5 to form the key intermediate 6 which possessed the desired cis‐fused ring configuration, and all the caron atoms needed to complete the synthesis of 16a and 18a.
Heterocyclic Spiro‐naphthalenones. Part I: Synthesis and reactions of some spiro [(1 H‐naphthalenone)‐1,3′‐piperidines]
Authors: Berney Daniel , Schuh Karlheinz 
Published: December 2004

AbstractThe title compounds 14–16 were obtained via an intramolecular Mannich condensation by treating 11–13 with CH2O at RT. The unsaturated ketones 14 and 15 were reduced to the allylic alcohols 18 and 19 respectively. Ring cleavage of compound 18 on treatment with 2N HCl gave the substituted aminopropanol 20. The allylic alcohols 18 and 19 were hydrogenated to 22 and 23 respectively. With CH2O, the amino‐alcohol 23 gave the methano‐naphthoxazocine 24, whereas 22 and 23, on heating in polyphosphoric acid (PPA), afforded the naphthazepines 25 and 26 respectively. With organolithium compounds, the unsaturated ketones 14 and 16 gave the teriary allylic alcohols 27–29, which were hydrogenated and dehydrated to the olefins 36–40; these were cyclized via an intramolecular alkylation to the methanodibenzo‐octahydrocyclooctapyridines 41–43. On heating in PPA, the allylic alcohol 29 was converted into the naphthazepine 44. With CH2O, the naphthol 49 gave the naphthoxazocine 50, in equilibrium with the spiro‐naphthalene‐pyrrolidinone 51 in solution. Finally, in the presence of CH2O, the naphthazepine 57 afforded the methano‐naphthazepinone 58, which, by a 4‐stage degradation, was transformed to the benzisoquinoline 62.