bluuebunny/crossref_metadata_2025 huggingface dataset:
Enzymatische Acetylierung von (±)‐1‐Phthalimido‐2‐propanol
Authors: Jeromin Günter E. , Weise Sven
Published: July 2007

Enzymatic Acetylation of (±)‐1‐Phthalimido‐2‐propanol

1‐Phthalimido‐2‐propanol [(±)‐1] is an N‐protected derivative of 1‐amino‐2‐propanol. By irreversible enzymatic acetylation of the racemate (±)‐1, (+)‐2‐acetoxy‐1‐(phthalimido)propane [(+)‐2] and (+)‐1‐phthalimido‐2‐propanol [(+)‐1] have been isolated on a preparative scale in good optical and chemical yields. Both optically active compounds are useful chiral intermediates.
Regio‐ and diastereoselective ene reactions of singlet oxygen with dialkyl‐substituted acrylic esters
Authors: Adam Waldemar , Nestler Bernd
Published: July 2007

Photooxygenation of methyl (E)‐ and (Z)‐2‐methyl‐4‐phenyl‐2‐pentenecarboxylates (E‐1, Z‐1) afforded the hydroperoxy esters (R*,S*)‐2a and (S*,S*)‐2b through regiospecific and diastereo‐selective ene reaction of singlet oxygen at the α‐methyl group with a diastereomeric ratio (d.r.) of 2a:2b ca. 80:20 for E‐1 and ca. 65:35 for Z‐1. The relative configurations of 2a, b were established by chemical correlation through triphenylphosphine reduction of the allylic hydroperoxy esters 2a, b to the allylic hydroxy esters 4a, b and subsequent catalytic hydrogenation to the literature‐known saturated hydroxy esters 5a, b (from pure 4a) and 5c, d (from pure 4b). The appreciable diastereoselectivity (d.r. ca. 80:20) observed for the E‐1 isomer is explained in terms of the cis effect, by coordinating the allylic hydrogen of the stereogenic C‐4 position to the terminal oxygen of the postulated perepoxide‐like structure.
Mikrobiologische und Enzymatische Reaktionsstufen in der Synthese von Prostacyclin‐Analoga
Authors: Petzoldt Karl , Dahl Helmut , Skuballa Werner , Gottwald Matthias
Published: July 2007

Microbiological and Enzymatic Transformations in the Synthesis of Prostacyclin Analogues

For the synthesis of prostacyclin analogues, enzymatic and microbiological transformations are described leading to homochiral bicyclooctane building units.
Organoboron monosaccharides, XVIII. Stereoselective syntheses of β‐D‐lyxofuranosyl glycosides
Authors: Dahlhoff Wilhelm V.
Published: July 2007

Methyl and phenyl β‐D‐lyxofuranoside (3a and 3b) are prepared by reaction of 5‐O‐acetyl‐2,3‐O‐ethylboranediyl‐α‐D‐lyxofuranosyl bromide (1) with sodium methoxide and sodium phenoxide to give the protected glycosides 2a, b followed by deboronation and deacetylation. The protected α‐D‐lyxofuranosyl disaccharides 2c, d are synthesized by treatment of 1 with 1,2:3,4‐di‐O‐isopropylidene‐α‐D‐galactopyranose and 1,2:5,6‐di‐O‐isopropylidene‐α‐D‐glucofuranose after the former has been converted to its sodium organooxytriethylborate and the latter has been O‐tributylstannylated. 2c and 2d are deboronated and deacetylated to give 3c and 3d, respectively. 2,3,5‐Tri‐O‐acetyl‐β‐D‐lyxofuranosyl glycosides (4a–d) are obtained from 3a–d by acetylation.
Variceramides, three new sphingolipids from the marine sponge Ircinia variabilis
Authors: Cafieri Francesco , Fattorusso Ernesto
Published: July 2007

From the marine sponge Ircinia variabilis, three new ceramides, variceramides 1a–3a, have been isolated. Their structures were deduced from spectroscopic studies and by acid hydrolysis.
Synthese von 4,8‐Dimethoxy‐1,5‐naphthalindiol und dessen Oxidation zu 4,8‐Dimethoxy‐1,5‐naphthochinon
Authors: Laatsch Hartmut
Published: July 2007

Synthesis of 4,8‐Dimethoxy‐1,5‐naphthalenediol and Its Oxidation to 4,8‐Dimethoxy‐1,5‐naphthoquinone

Formation of the new 1,5‐naphthoquinone 3 was achieved by methylation of 1,4,5,8‐naphthalenetetrol (1a) and oxidation of the dimethyl ether 1c obtained thereof. In the presence of water, 3 yields the monoether 5a. Methylation of binaphthazarin (6a) seems to proceed in a similar manner.
Synthesis of 1‐aminoalkylphosphonic acids via amidoalkylation of phosphorous acid by N,N′‐alkylidenebisamides
Authors: Soroka Miroslaw , Jaworska Dorota , Szczȩsny Zbigniew
Published: July 2007

N,N′‐Alkylidenebisamides 1, totally unsuitable as amidoalkylating agents toward phosphorous acid, react with its “activated” form prepared “in situ” from phosphorus(III) chloride and acetic acid to give the desired 1‐aminoalkylphosphonic acids 2 in high yields.
Furocoumarin‐, naphthofuran‐, and furoquinoline‐annulated 1,2‐dioxetanes: Synthesis, thermolysis, and mutagenicity
Authors: Adam Waldemar , Hauer Hermann , Mosandl Thomas , Saha‐Möller Chantu R. , Wagner Willi , Wild Dieter
Published: July 2007

The low temperature photooxygenation of the furocoumarins1a–e, the naphthofurans1f–h, and the furoquinoline1iafforded the corresponding dioxetanes2in good yields, except the linearly annulated naphthofuran1f, which led exclusively to the allylic hydroperoxide5fby ene reaction with singlet oxygen. The dioxetanes2were rigorously purified by means of low temperature silica gel chromatography and fully characterized. Thermolysis of the furocoumarin dioxetanes2a–eled to the expected cleavage products3a–e(acetyloxy‐ and acetyl‐substituted coumarins), while the naphtho‐ and quino‐linofuran dioxetanes2g–igave in addition to the cleavage products3g–ialso the spiroepoxides4g–i. Intramolecular electron transfer from the aromatic moiety to the dioxetane ring, with subsequent cyclization of the radical‐ion species and fragmentation is postulated as mechanism for the formation of this novel rearrangement product of dioxetanes. On heating in chloroform the spiroepoxides4g,hrearranged into the 1,3‐dioxole6g, but heating of4gin methanol gave the dioxine7gby trapping of the dipolar intermediate. — The furocoumarin dioxetanes2a,c,dshowed high mutagenic activity in theSalmonella typhimuriumstrain TA 100 but not in the strain TA 2638. The naphtho‐ and quinolinofuran dioxetanes2h,iand the spiroepoxides4g,hwere nonmutagenic in the TA 100 strain. Epoxide‐like DNA damage appears to be responsible for the mutagenicity of the furocoumarin dioxetanes2a,c,d.
Concave reagents, 3. Synthesis, basicity, and conformation of new concave pyridines
Authors: Lüning Ulrich , Baumstark Roland , Peters Karl , von Schnering Hans Georg
Published: July 2007

Eight new bimacrocyclic concave pyridines 9 and six monomacrocyclic and open‐chain analogues 10–12 were synthesized in overall yields up to 40% (up to 75% for nonmacrocyclic pyridines) starting from 2,6‐pyridinedicarbaldehydes 1, diamines 2 and diacyl dichlorides 7. Their basicities cover a range of more than three orders of magnitude. They are determined not only by the substitution pattern of the pyridine ring, but also by the overall structure of the whole molecule and by its ability to stabilize the positive charge of a proton intramolecularly. The conformations of the bimacrocyclic bislactams 9 in solution and in the solid state were investigated spectroscopically, the structure of 9b could be determined by X‐ray analysis.
Synthesis of acyclic analogs of N‐acetylmuramyl‐L‐alanyl‐D‐isoglutamine (MDP)
Authors: Danklmaier Johann , Hünig Helmut
Published: July 2007

The syntheses of the acyclic MDP analogs 27–37 is described, the carbohydrate moiety of muramic acid being replaced by acyclic amino alcohol structures. Their preparation was accomplished by hydrolytic cleavage of the cyclic, disubstituted 3‐morpholinones 2–5 and protection of the free amino group to give the compounds 6–9. Coupling with the dipeptide L‐alanyl‐D‐isoglutamine benzyl ester, cleavage of the N‐protecting group, acylation with acyl chains of various lengths and hydrogenation produced the title compounds 27–37. The latter exhibit variable lipophilic character.
Pheromone synthesis, CXVIII. Synthesis of the enantiomers of (E)‐1‐ethyl‐5‐methyl‐4‐heptenyl acetate (quadrilure), the aggregation pheromone of Cathartus quadricollis
Authors: Mori Kenji , Puapoomchareon Prapai
Published: July 2007

The synthesis of (R)‐ and (S)‐quadrilure (1) was achieved starting from (R)‐ and (S)‐methyl 3‐hydroxypentanoate (2) in 8 steps (34–35% yield).
Cyclit‐Reaktionen, XVII. Synthese von Pseudodisacchariden und Varianten von Valiolamin und Valiol
Authors: Paulsen Hans , Mielke Burkhard
Published: July 2007

Cyclitol Reactions, XVII. — Synthesis of Pseudodisaccharides and of Derivatives of Valiolamine and Valiol

Epoxid 8 has been synthesized from 2. Oxirane ring cleavage of 8 yields 1L‐6‐Amino‐6‐desoxy‐2‐C‐hydroxymethyl‐myo‐inositol 11. Analogous epimino compound 19 is obtained by neighbour group participation from inosamine 18. Debenzylation of 19 results in 1L‐2,3‐Didesoxy‐2,3‐epimino‐4‐C‐hydroxymethyl‐epi‐inositol 28 having structural analogy to the α‐glucosidase inhibitor conduritol B epoxide. Imino‐linked pseudodisaccharide 43 is prepared by condensation of 18 with 36. Ether‐linked pseudodisaccharide 49 can be obtained by coupling of 44 and 45.
Synthese neuer heteroanellierter 8‐Azapurine
Authors: Ried Walter , Laoutidis Joannis
Published: July 2007

Synthesis of New Heteroannulated 8‐Azapurines

The 1,2,3‐Triazoles 1 react with biselectrophiles 2, 3, 4, 7, and 9 to the pyrimido‐annulated 8‐Azapurines 5a–d, 6a, b, 8a–c, and 10a–d.
Natural product chemistry, 134. Syntheses of the natural coumarins gleinene and gleinadiene
Authors: Reisch Johannes , Wickramasinghe Anura , Wickremaratne D. B. Mahinda
Published: July 2007

The 5,7‐dimethoxycoumarins, gleinene (3b) and gleinadiene (2), which naturally occur in Murraya gleinei root bark, have been synthesized in four steps from 7‐hydroxy‐5‐methoxycoumarin (1a) in overall yields of 45% and 19%, respectively.
Synthesis and oxidation of pregna‐3,5‐dien‐20‐ols and ‐20‐one and selective reduction of pregna‐3,5‐dien‐20‐one
Authors: Göndös György , Orr James C.
Published: July 2007

Pregna‐3,5‐dien‐20‐one (4) and (20S)‐ and (20R)‐pregna‐3,5‐dien‐20‐ol (2 and 3) were synthesized from progesterone. Oxidation of a mixture of 2 and 3 with Jones reagent gave 4, while a large excess of Jones reagent afforded besides 4, 6‐oxoprogesterone (5), 6β‐hydroxyprogesterone (6) and 5α‐pregnane‐3,6,20‐trione (7). With L‐selectride as reducing agent, reduction of 4 led to 2 and 3 in a ratio of about 1:1. However, some reducing agents gave a higher ratio of isomer 3.
Synthesis of trialkylsiloxy‐substituted and other 5,6‐dihydro‐4H‐1,2‐oxazines by hetero diels‐alder reactions of nitroso alkenes — Preparative scope and diastereoselectivity
Authors: Hippeli Claudia , Reißig Hans‐Ulrich
Published: July 2007

A variety of 5,6‐dihydro‐4H‐1,2‐oxazines 3 and 4 is prepared in good yields from silyl enol ethers 1 and nitroso alkenes 2a or 2b, respectively. A systematic variation of substituents reveals preparative scope and limitations of this hetero Diels‐Alder reaction with inverse electron demand. The cycloaddition is rather sensitive with regard to steric effects – in particular, large groups at C‐1 of the silyl enol ethers 1 completely prevent the reaction. On the other hand, excellent diastereo‐selectivities are observed employing appropriately substituted olefins. The presented method for the synthesis of 1,2‐oxazines also displays high regio‐ and periselectivity as is demonstrated by transformations 1r→3r and 13→14.
Allo‐, Epiallo‐ und Pseudoyohimbane sowie Heteroyohimbane durch Reaktion eines tetracyclischen Aldehyds mit Acetessigester in verschiedenen Lösungsmitteln
Authors: Rosenmund Peter , Casutt Michael , Wittich Michael
Published: July 2007

Allo‐, Epiallo‐, and Pseudoyohimbanes as well as Heteroyohimbanes by Reaction of a Tetracyclic Aldehyde with Acetoacetate in Different Solvents

The reaction of methyl acetoacetate with 4 in CH3OH/ CH3ONa leads to 11 and 12 with yohimbane skeleton but bicyclo ring E. In DMF/tBuOK, the epialloheteroyohimbane 13 is produced in fairly good yield, whereas in THF/NaH the allo‐19‐hydroxyyohimbinone 17 is formed, which undergoes thermal decomposition to the alloyohimb‐18‐enone 19. Finally, a full description of an early mentioned synthesis of rac‐de‐plancheine (7) is given.
Darstellung und Charakterisierung von diastereomeren (4S)‐3‐Acetyl‐2‐aryl‐5,5‐dimethyl‐4‐thiazolidincarbonsäuren
Authors: Györgydeák Zoltán , Kajtár Judit , Kajtár Márton , Kajtár‐Peredy Mária
Published: July 2007

Synthesis and Characterisation of Diastereomeric (4S)‐3‐Acetyl‐2‐aryl‐5,5‐dimethyl‐4‐thiazolidinecarboxylic Acids

The condensation of aromatic aldehydes 1 and D‐penicillamine (2) in aqueous methanol gives (4S)‐2‐aryl‐5,5‐dimethyl‐4‐thiazolidinecarboxylic acids 3 with alternating diastereoselectivity in position 2. Acetylation of the products with acetic anhydride in pyridine or in water gives rise to (2S,4S)‐3‐acetyl‐2‐aryl‐5,5‐dimethyl‐4‐thiazolidinecarboxylic acids 5. Use of a HCl/dioxane system in the reaction of N‐acetyl‐D‐penicillamine (6) with aldehydes made possible the effective preparation of (2R,4S) compounds 8. The diastereomeric compounds 5 and 8 were characterized by 1H‐ and 13C‐NMR data and optical rotation and CD. The results were compared with those compiled from the already synthesized diastereomeric (4R)‐3‐acetyl‐2‐aryl‐4‐thiazolidinecarboxylic acids.
Synthesis of mono‐ and sesquiterpenoids, XIX. Synthesis of the enantiomers of ancistrofuran, a defensive compound from Ancistrotermes cavithorax
Authors: Mori Kenji , Suzuki Norio
Published: July 2007

The synthesis of the enantiomers (1 and 1′) of ancistrofuran was achieved starting from (S)‐3‐hydroxy‐2,2‐dimethylcyclohexanone.
Synthesis of polyfunctionally substituted pyridazines
Authors: Ghozlan Said Ahmed Soliman , Mohamed Mona Hassan , Fakhr Yehia , Elnagdi Mohamed Hilmy
Published: July 2007

The pyridazines 3, 4, 5, and 7 were obtained by reaction of the hydrazone derivatives 2 with several reagents. By treatment of 5 with acetic acid/hydrochloric acid, the pyrazolo[4,3‐c]‐pyridazine 6 was formed. The pyrido‐pyridazine derivatives 8 and 9 were obtained by reaction of 2 and 3 with malononitrile and ethyl cyanoacetate, respectively, and the isoxazolo‐pyridazines 11 by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium ethoxide solution. The intermediate 9 was separated by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium acetate solution.
Synthese von Pakyonol, einem macrocyclischen Bis(bibenzylether) aus Mannia fragrans
Authors: Nógrádi Mihály , Vermes Borbála , Kajtár‐Peredy Mária , Novikov V. P.
Published: July 2007

Synthesis of Pakyonol, a Macrocyclic Bis(bibenzyl ether) from Mannia fragrans

The unambigous synthesis of pakyonol (1), a bis(bibenzyl ether) with a 20‐membered ring by Ullmann, Wittig, and modified Wurtz reaction is reported.
Diastereoselectivity in the halolactonization of 2‐alkoxy‐4‐alkenoic acids and‐4‐alkenamides
Authors: Maier Martin E. , Kandler Helmut , Haller Bernd U. , Hofmann Josef H. , Fischer Helmut
Published: July 2007

Iodolactonization of 2‐alkoxy‐ and 2‐hydroxy‐4‐alkenoic acids 3a–d under kinetic control gives mixtures of cis‐ and trans‐lactones 6a–d and 7a–d with cis‐selectivity up to 5.5:1.0. The bromolactonization of carboxamides 4 a, 4 c, and 5 c shows moderate 1,3‐asymmetric induction, favoring the trans‐lactones 9 with a selectivity of up to 2.5:1.0.
Synthesis of a new azapeptide with renin‐inhibiting properties
Authors: Gante Joachim , Weitzel Reinhard
Published: July 2007

Boc‐hydrazine (1) was treated with 4‐nitrophenyl chloroformate (2) to give Boc‐Azagly 4‐nitrophenyl ester (3). Reaction of 3 with H‐ACHP‐Ile‐3‐pyridylmethylamide5) (4) provided Boc‐Azagly‐ACHP‐Ile‐3‐pyridylmethylamide (5). This was deprotected with HCl/dioxane to give H‐Azagly‐ACHP‐Ile‐3‐pyridylmethylamide dihydrochloride (6), which was coupled with Boc‐Phe‐OH (7) by the carbodiimide/HOBt method providing the final azapeptide Boc‐Phe‐Azagly‐ACHP‐3‐pyridyl‐methylamide (8). This compound was shown to be a renin inhibitor of high specificity.
Synthesis and structure of some thiazole derivatives
Authors: Badawy Mohamed A. , Abdel‐Hady Sayed A. , Ibrahim Yehia A.
Published: July 2007

The addition of thiosemicarbazones 1 to α‐halo acids 2 is shown to give 2‐hydrazino‐2‐thiazolin‐4‐ones 3 and not 3‐substituted 2‐imino‐3‐(methyleneimino)thiazolidin‐4‐ones 4. The independent synthesis of 2‐thiazolin‐4‐one derivatives 3 is also described.
Studien zur Synthese helicaler Naphthochinon‐Oligomerer, I. 2,2′;3′,2″‐Ter‐ und 2,2′;3′,2″;3″,2‴‐Quater(1,4‐naphthochinon)
Authors: Laatsch Hartmut
Published: July 2007

Studies in the Synthesis of Helical Naphthoquinone Oligomers, I. — 2,2′;3′,2″‐Ter‐ and 2,2′;3′,2′;3′,2‴‐Quater(1,4‐naphthoquinone)

2,2′;3′,2′‐Ter(1,4‐naphthoquinone) (6a) and 2,2′;3′,2″;3″,2‴‐quater(1,4‐naphthoquinone) (8a) are obtained by cooxidation of the phenolic precursors 16a and 2b. It is shown, that partially reduced 6a cyclizes under basic conditions yielding triphthaloylbenzene (7); therefore, it is also a possible intermediate of the synthesis of 7 by phenol/quinone addition of 2a to 1a. Spectroscopic data suggest that the tetrameric hydroquinonylquinone 8b is stabilized by hydrogen bonding, forming a helical quinhydron structure.
3a‐Azaazulenone mit einer Carbonylgruppe im Fünfring
Authors: Flitsch Wilhelm , Hohenhorst Manfred
Published: July 2007

3a‐Azaazulenones with a Carbonyl Group in the 5‐Membered Ring

Syntheses and properties of unstable 3a‐aza‐3‐azulenones 1 are described. Attempts of a synthesis of 3a‐aza‐1‐azulenones 2 resulted in a formation of rearranged pyridones 10 and a dimer 11 indicating the unstable intermediates 2.
Reaktionen der Trialkylsilyl‐trifluormethansulfonate, X. N‐(Trifluoracetyl)‐α,β‐didehydro‐α‐aminosäureester durch Trimethylsilanol‐Eliminierung aus 2‐[(Trifluoracetyl)amino]‐3‐(trimethylsiloxy)carbonsäureestern
Authors: Seethaler Toni , Simchen Gerhard
Published: July 2007

Reactions of Trialkylsilyl Trifluoromethanesulfonates, X. – N‐(Trifluoroacetyl)‐α,β‐didehydro‐α‐amino Carboxylic Acid Esters from 2‐(Trifluoroacetyl)amino]‐3‐(trimethylsiloxy)carboxylic Acid Esters by Elimination of Trimethylsilanol

α‐Amino‐β‐(trimethylsiloxy)carboxylates 4 are obtained by trimethylsiloxy alkylation of the ketene acetal 1 with aldehydes 2 in the presence of trimethylsilyl triflate (3). β‐Elimination of trimethylsilanol from the esters 4 by means of trifluoroacetic acid anhydride (8) or methanesulfonic acid anhydride (15) yields (Z)‐didehydro amino acid esters 7. The course of the elimination reaction is studied.
Struktur und Geruch, XIII. Synthese und olfaktorische Eigenschaften von Megastigmatrienon‐Analoga
Authors: Weyerstahl Peter , Meisel Thomas , Mewes Klaus , Negahdari Shoreh
Published: July 2007

Structure–Odor Correlation, XIII1). – Synthesis and Olfactive Properties of Megastigmatrienone Analogues

The key compound 9 was readily prepared in larger quantities by an improvement of a known procedure. Addition of carbanions to the unprotected ketone 9 gives the hydroxy ketones 16–21 via the acetals 10–15. Dehydration of 16–20 furnishes the dienones 2–6 while 7 is available in fair yield via the acetoacetate 21. Through intramolecular cyclization also the ester 26 is formed which affords with NaOH the keto ester 29 by a retro‐Michael reaction. The diketone 28 (obtained from 29) can be reduced selectively to give 30, dehydration of which leads to 31/32. – The odor of 2 (camphor, sweet, wood, plum) is the olfactive link between the odor of isophorone and megastigmatrienone (A). Elongation of the alkyl group (→ 3–5) leads first to a herbaceous, then to a leathery note. The one‐diene‐one 7 smells unexpectedly weak. For the very strong odor (tobacco, wood, plum) of A obviously the total osmophor is responsible including the unsaturated side chain.
[2.2]γ‐Pyronopyridinophane: Synthese und Untersuchungen zur konformativen Beweglichkeit
Authors: Flitsch Wilhelm , Niedenbrück Matthias
Published: July 2007

[2.2](2,6)γ‐Pyronopyridinophanes: Synthesis and Investigation of the Conformational Flexibility

The [2.2](2,6)γ‐pyronopyridinophane 1 has been obtained via the bis(thio ether) 3 by oxidation with m‐chloroperbenzoic acid and subsequent pyrolysis. Bromination of the bis(sulfone) 6 and Ramberg‐Bäklund reaction gave the olefinic sulfone 9 which was transformed into the [2.2](2,6)γ‐pyronopyridinophan‐1‐ene 2 by heating. The ring inversion of the heterophanes 1 and 2 was studied using dynamic NMR spectroscopy.
Synthese der Markierungssubstanz der Kirschenfruchtfliege Rhagoletis cerasi L.
Authors: Küchler Birgit , Voß Gundula , Gerlach Hans
Published: July 2007

Synthesis of the Oviposition‐Deterring Pheromone of Rhagoletis cerasi L.

The oviposition‐deterring pheromone of Rhagoletis cerasi L. (−)‐(8R,15R)‐1 and a mixture of the two compounds (−)‐(8R and 8S,15R)‐1 have been synthesized. In the presence of the 1,5‐cyclooctadiene–CuCl complex as catalyst the Grignard reagent of (−)‐(R)‐4 reacts with the epoxides (−)‐(S)‐5 and (±)‐5 to give (−)‐(7R,14R)‐6 and (−)‐(7R and 7S,14R)‐6. The optically active reagent (−)‐(R)‐4 has been prepared from ( + )‐(R)‐1,2‐epoxypropane. (−)‐(S)‐5 has been prepared from L‐malic acid dimethyl ester. – After converting the 7‐hydroxy groups of (7R,14R)‐6 and (7R and 7S,14R)‐6 into benzyl ethers 7, treatment with methanolic HCl solvolyzed the silyl ether and tricyclic orthoester groups to give the methyl esters (8R,15R)‐20 and (8R and 8S,15R)‐20. Next, these compounds were transformed into the benzyl ether–benzyl esters (8R,15R)‐21 and (8R and 8S,15R)‐21 that could be β‐glucosylated in high yields with tetrapivaloyl‐α‐D‐bromoglucose to give (8R,15R)‐22 and (8R and 8S,15R)‐22. Hydrogenolysis of the benzyl groups in 22 gave the corresponding 8‐hydroxy acids that could be activated as mixed anhydrides and reacted with 2‐aminoethanesulfonic acid to give the taurinamides (8R,15R)‐23 and (8R and 8S,15R)‐23. In the last step the pivaloyl groups of the glucose moiety of the molecules were removed by alkaline hydrolysis. Treatment of the hydrolysis products with an Amberlyst 15 (H+ form) ion exchanger and then with ammonia gave (8R,15R)‐1 and (8R and 8S,15R)‐1 as ammonium salts. The tetraacetyl‐β‐glucosides (13R)‐2 and (13S)‐3 have been synthesized and allow to deduce the (15R) configuration for the pentaacetyl derivative of the natural compound 1 by comparing their 1H‐NMR spectra.
Nachweis maskierter, langkettiger α‐Hydroxyaldehyde in Säugetiergewebe‐Lipiden
Authors: Lutz Arnulf , Spiteller Gerhard
Published: July 2007

Evidence for the Occurrence of Masked α‐Hydroxy Aldehydes in Mammalian Tissue Lipids

If samples of mammalian tissue lipids are treated with dithioethyleneglycol, Et2O ‐ BF3, and acetic acid, bound α‐hydroxy aldehydes are converted into dithiolane derivatives. After reduction, they are separated from large amounts of accompanying lipid derivatives by TLC. The trimethylsilylated samples have been investigated by GLC and GLC/MS.
Enantioselective total synthesis of harmonine, a defence alkaloid of ladybugs (Coleoptera: Coccinellidae)
Authors: Enders Dieter , Bartzen Dominika
Published: July 2007

An efficient and highly enantioselective (ee > 97%) total synthesis of the ladybug defence alkaloid (17R,9Z)‐1,17‐diaminooctadec‐9‐ene [(R,Z)‐1, harmonine] in good overall yield is described. As the key step for the generation of the stereogenic center, asymmetric CC bond formation by nucleophilic addition of methyllithium to an aldehyde SAMP hydrazone is used.
Secondary metabolites by chemical screening, 18. Narbosines, new carbohydrate metabolites from Streptomyces
Authors: Henkel Thomas , Breiding‐Mack Sabine , Zeeck Axel , Grabley Susanne , Hammann Peter E. , Hütter Klaus , Till Gudrun , Thiericke Ralf , Wink Joachim
Published: July 2007

In the culture broth of two new Strepomyces strains several novel 2,3,6‐trideoxy‐L‐threo‐hexose (rhodinose) metabolites, narbosines A to E (2–6, 8, 9), were detected besides α‐N‐acetylanhydro‐L‐ornithine (11) by using the chemical screening method. Their structures were deduced from spectroscopical data as well as from chemical transformations. Narbosine A (2/3) was shown to be a 1:1 anomeric mixture of α‐L‐rhodinopyranosyl‐(1→4) ‐α/β‐L‐rhodinopyranose, the others are partially oxidatively and reductively transformed derivatives of 2/3. A destinct antiviral activity was observed for the described metabolites.
Formation of quinolines from 2‐phenylbenzopyrylium chloride
Authors: Sonnenschein Helmut , Schmitz Ernst , Hiller Wolf
Published: July 2007

The quinolines 5a–e are prepared by thermal treatment of 2‐phenylbenzopyrylium chloride (4) with aromatic amines. The substitution pattern of the products shows that an unusual Skraup synthesis has taken place.
An efficient synthesis of cis‐ and trans‐2‐aminocyclohexanecarboxamides and their N‐substituted derivatives
Authors: Göndös György , Szécsényi István , Dombi György
Published: July 2007

In this paper we describe a new approach to cis‐ and trans‐2‐aminocyclohexanecarboxamides and their N‐substituted derivatives. Which proceeds much faster and in higher yields than the methods described in the literature and usually employed in peptide chemistry. This method opens a route to the production of many previously unknown cis‐ and trans‐2‐aminocyclohexanecarboxylic acid derivatives.
Studies on N‐Acetylation of 3‐Aryl‐5‐ethyl‐4,5‐dihydro‐1,2,4‐oxadiazoles
Authors: Srivastava R. M. , Carpenter G. B.
Published: July 2007

A facile synthesis of 2‐acetyl‐3‐aryl‐5‐ethyl‐2,5‐dihydro‐1,2,4‐oxadiazoles 2 is described.
Reactions of organic anions, 182. Vicarious nucleophilic substitution of a hydrogen atom in 1‐fluoro‐2,4‐dinitrobenzene (Sanger's Reagent)
Authors: Mąkosza Mieczyslaw , Stalewski Jacek
Published: July 2007

Reactions of carbanions of aryl chloromethyl and dichloromethyl sulfones 3 and 4 and tert‐butyl chloro‐ and dichloroacetates (5 and 6) with 1‐halo‐2,4‐dinitrobenzenes 1 and 2 proceed by nucleophilic replacement of a hydrogen atom. The SNAr of the halogen atom occurs to a negligible extent.
Tumor‐associated antigen synthesis synthesis of the gal‐α‐(1→3)‐gal‐β‐(1→4)‐GlcNAc epitope a specific determinant for metastatic progression?
Authors: Schaubach Regine , Hemberger Jürgen , Kinzy Willy
Published: July 2007

A versatile synthesis of the Gal‐α‐(1→3)‐Gal‐β‐(1→4)‐GlcNAc epitope coupled to an alkyl spacer molecule could be developed. The important building block 3′‐allyl‐D‐lactal 6 was prepared in high yield by the action of dibutyltin oxide and allyl bromide on D‐lactal and converted in several steps into the lactosamine derivative 13 with free 3′‐OH group. Stereoselective glycosidation with the β‐trichloroacetimidate of benzylated D‐galactose 18 led to the trisaccharide in high yield. Activation of the protected Gal‐α‐(1→3)‐Gal‐β‐(1→4)‐GlcNAc derivative 21 by desilylation and trichloroacetimidate formation followed by glycosidation with ethyl 9‐hydroxynonanoate furnished the spacer‐bound trisaccharide hapten 24 in excellent yield after simple two‐step deprotection. The trisaccharide hapten 24 can easily be used as immunogen after coupling to an immunogenic carrier.
Derivate natürlicher Tetrapyrrole, Synthese einiger Modellverbindungen für die Photodynamische Therapie
Authors: Mackenbrock Ursula , Risch Nikolaus
Published: July 2007

Natural Tetrapyrrol Derivatives, Synthesis of Some Model Compounds for the Photodynamic Therapy

In photodynamic therapy, di‐ and polymeric porphyrins with ether, ester or direct CC linkages are the active components of hematoporphyrin derivative. Here we describe the synthesis of some new model compounds for such ether/ester dimers.
Stereoselektive Umsetzungen von rac‐, (R), oder (S)‐5‐Alkyliden‐2‐t‐butyl‐3‐methyl‐4‐oxo‐1‐imidazolidincarbonsäure‐t‐butylestern (chirale 2,3‐Dehydroaminosäure‐Derivate) und Herstellung einiger nichtproteinogener Aminosäuren
Authors: Seebach Dieter , Bürger H. Michael , Schickli Christof P.
Published: July 2007

Stereoselective Conversions of t‐Butyl rac‐, (R)‐, or (S)‐5‐Alkylidene‐2‐t‐butyl‐3‐methyl‐4‐oxo‐1‐imidazolidinecarboxylates (Chiral 2,3‐Dehydroamino Acid Derivatives) and Preparation of Some Nonproteinogenic Amino Acids

The reacivity of the alkylidene derivatives 1–11 specified in the title and prepared in two operational steps from commercially available Boc‐BMI and aldehydes is investigated. – According to high‐field 1H‐NMR analysis of the crude products, additions of HH and DD (catalytic hydrogenation, products 12–20, of RH (BF3‐activated R2CuLi/LiI and protonation, products 21–29), and of Cl2C (CHCl3/NaOH, products 33, 34) occur with complete selectivity from the face opposite to the t‐butyl group. The doubly unsaturated carbonyl derivative 11 reacts with dibutyl cuprate in the δ position, again with formation of a single diastereomer 32, while trifluoroethylidene‐Boc‐BMI 3a is reduced to the difluoro analogue 30 by this cuprate. – Li dienolates are generated by deprotonation with LDA of the ethylidene (2a) and butylidene compound 4a; subsequent alkylations (with primary and secondary halides, products 35–41) and hydroxyalkylations (with aldehydes, products 42–44) lead to single products of electrophilic attack in the a carbonyl position (C‐5 of the imidazolidinone ring) under kinetic control. On the other hand, reaction of the 2a‐derived dienolate with benzaldehyde under equilibrating conditions furnishes the four possible (E/R, E/S, Z/R, and Z/S) γ adducts 45–48. – A combination of methods – 1H‐ and 13C‐NMR spectroscopy, NOE measurements, spectroscopic analogies, chemical correlation (with authentic samples or by spectroscopic or optical comparison), and X‐ray analysis (Table 1, Figure 1, Schemes 1 and 2) – is used to assign the product configurations and thus the stereochemical course of the reactions. Some unusual amino acids (50–52, 54, 55) are prepared by hydrolysis of the corresponding imidazolidinones.
Natural product chemisrty, 143. Convenient synthesis of isoacronycine and some other new acridone derivatives
Authors: Reisch Johannes , Herath H. M. T. Bandara , Kumar N. Savitri
Published: July 2007

The iodination of 1,3‐dihydroxy‐9‐acridone (1), 1‐hydroxy‐3‐methoxy‐10‐methyl‐9‐acridone (2) and 1,3‐dihydroxy‐10‐methyl‐9‐acridone (3) yields 1,3‐dihydroxy‐2,4‐diiodo‐9‐acridone (4), 1‐hydroxy‐2‐iodo‐3‐methoxy‐10‐methyl‐9‐acridone (5) and 1,3‐dihydroxy‐2‐iodo‐10‐methyl‐9‐acridone (6), respectively. The methylation of 4 and 5 gives 2,4‐diiodo‐1,3‐dimethoxy‐10‐methyl‐9‐acridone (7) and 2‐iodo‐1,3‐dimethoxy‐10‐methyl‐9‐acridone (9), respectively. The direct CC coupling of 2‐methyl‐3‐buten‐2‐ol to the compounds 5, 7 and 9 by palladium catalysed Heck condensation method gives three new acridone derivatives 1‐hydroxy‐2‐(3‐hydroxy‐3‐methyl‐1‐butenyl)‐3‐methoxy‐10‐methyl‐9‐acridone (10), 2,4‐bis(3‐hydroxy‐3‐methyl‐1‐butenyl)‐1,3‐dimethoxy‐10‐methyl‐9‐acridone (12) and 2‐(3‐hydroxy‐3‐methyl‐1‐butenyl)‐1,3‐dimethoxy‐10‐methyl‐9‐acridone (13) while compound 6 is converted into isonoracronycine (11). The methylation of 11 yields isoacronycine (14).
Zur stereoselektiven Synthese von 1‐O‐Alkyl‐3‐O‐benzyl‐sn‐glycerolen und 1‐O‐Alkyl‐2‐O‐methyl‐3‐O‐β‐D‐glycosyl‐sn‐glycerolen
Authors: Bauer Friederike , Rueß Klaus‐Peter , Liefländer Manfred
Published: July 2007

Stereoselective Synthesis of 1‐O‐Alkyl‐3‐O‐benzyl‐sn‐glycerols and 1‐O‐Alkyl‐2‐O‐methyl‐3‐O‐β‐D‐glycosyl‐sn‐glycerols

Starting with D‐mannitol, the yield of the synthesis of 3‐O‐benzyl‐sn‐glycerol (1) could be improved. The regioselective alkylation of 1 at the primary hydroxy group to the 1‐O‐alkyl‐3‐O‐benzyl‐sn‐glycerols 3 was achieved by using the dibutylstannylene protecting group. The 1‐O‐alkyl‐2‐O‐methyl‐sn‐glycerols 4, readily obtainable from 3, were successfully glycosylated under the conditions of the Koenigs‐Knorr reaction to give 1‐O‐alkyl‐2‐O‐methyl‐3‐O‐β‐D‐glycosyl‐sn‐glycerols.
Pheromone synthesis, CXXXI. Synthesis of the four stereoisomers of 6,10,13‐trimethyl‐1‐tetradecanol, the aggregation pheromone of predatory stink bug, Stiretrus anchorago
Authors: Mori Kenji , Wu Jiang
Published: July 2007

The synthesis of the four stereoisomers of 6,10,13‐trimethyl‐1‐tetradecanol (1a), the male‐produced aggregation pheromone of the predatory stink bug Stiretrus anchorago, was achieved by starting from (R)‐citronellol (2a), methyl (R)‐ or (S)‐3‐hydroxy‐2‐methylpropanoate (10) and 4‐chloro‐1‐butanol (12a).
A novel one‐step synthesis of 4H‐furo[3,4‐b]pyrans and a transformation into a difuro[3,4‐b: 3′,4′‐e]pyridine
Authors: Martín Nazario , Segura José L. , Seoane Carlos , Soto José L. , Morales Margarita , Suarez Margarita
Published: July 2007

A simple one‐step synthesis of 2‐amino‐4‐aryl‐5‐oxo‐4H‐furo[3,4‐b]pyran‐3‐carbonitriles 7 is described. It involves reaction of 2,4(3H,5H)‐furandione (β‐tetronic acid) (5) with arylmethylenemalononitriles 4 in basic medium. Some substituent effects are noted and the assignments of 13C‐NMR spectra are discussed. Ring transformation of the furo[3,4‐b]pyran 7a leads to the difuro[3,4‐b:3′,4′‐e]pyridine 9.
Herkunft des Sauerstoffatoms im Furanring von F‐Säuren
Authors: Batna Andreas , Spiteller Gerhard
Published: July 2007

Origin of the Oxygen Atom in the Furan Ring of F Acids

Incubation experiments with 18O2 gas on suspension cultures of Saccharum spec. demonstrate that the oxygen atom in the furan ring of F acids 1 is derived from the air. This result points to the participation of lipoxygenase systems in the biosynthesis of these compounds. Specific incorporation into the furan ring, using an apparatus with 18O2 influx in portions, was confirmed by GC/MS analysis of the tetrahydofuran derivatives 2, obtained by esterification and hydrogenation of the corresponding furan derivatives 1.
Preparation and crystal structure of methyl [12‐acetyl‐8‐ethyl]‐bacteriopheophorbide d. – A new bacteriochlorophyll derivative
Authors: Senge Mathias O. , Bobe Frank W. , Huster Michael S. , Smith Kevin M.
Published: July 2007

Reaction of methyl bacteriopheophorbide d 2 in tetrahydrofuran with sodium methoxide led to oxidation of the ethyl side chain at position 12 to afford an acetyl group. Experiments with 18O2 suggest a mechanism via abstraction of a proton and reaction of the secondary radical formed with molecular oxygen. The implications of this mechanism for the biosynthesis of the bacteriochlorophylls are discussed. The 12‐acetyl compound 3 was investigated by X‐ray crystallography.
Synthesis of 6‐dimethylaminopurine 2′,3′‐dideoxynucleosides
Authors: Motawia Mohammed S. , El‐Torgoman Abdel Moneim , Pedersen Erik B.
Published: July 2007

The trimethylsilyated 6‐dimethylaminopurine 1 was coupled with the 2′,3′‐dideoxyribose derivatives 2a, b and 7 by using trimethylsilyl triflate as catalyst to yield the corresponding nucleosides 3a, b, 4a, b and 8, which were appropriately deprotected to give the desired nucleosides 5a, b and 9 as well as the related α‐isomers 6a, b and 10. The 2‐deoxyribose derivative 12 was mesylated at the 3′‐O‐position to give 13 which was coupled similarly with 1 to yield compound 14 and its α‐anomer 15. Compounds 14 and 15 were treated with tetrabutylammonium fluoride to give the desired 2′,3′‐didehydro‐2′,3′‐dideoxynucleoside analogue 16 and its α‐anomer 17.
Unexpectedly formed amino ketones, stereochemistry and conformation
Authors: Neszmélyi András , Lotter Hermann , Kiss Arpád , Pelczer István , Oszbach György
Published: July 2007

Benzaldehyde adds to pyrrolidine enamines of cyclohexanone and 4‐tert‐butylcyclohexanone to form 1 and 4, respectively. The unstable ketones were reduced to afford stable alcohols 2 and 5. The stereochemistry of 2 was verified by X‐ray diffraction. Unambiguous structure elucidation of 5 was achieved by two‐dimensional NMR spectroscopy and by considering the system of vicinal and long‐range proton‐proton coupling constants determined at 400 MHz and analyzed by spin simulation. 13C‐T1 relaxation times proved the anisotropic motion of the subunits of 5. An intramolecular hydrogen bridge is observed both in the 1H‐NMR and in the IR spectrum. The relative stereochemistry of the chiral centers of 5 was determined by inter‐subunit nuclear Overhauser enhancements. The conformation in solution was predicted by NOE restrained nonbonded energy calculation and molecular modeling. The enhancements computed with the refined geometry are in good agreement with the observed NOE values.
Synthese von rac‐Norartemeseol
Authors: Kirschning Andreas , Narjes Frank , Schaumann Ernst
Published: July 2007

Synthesis of rac‐Norartemeseol

The synthesis of the terpenoid rac‐norartemesol (1b) is accomplished using epoxide ring‐opening reactions as key steps. Thus, addition of the thio‐substituted allyl anion 2b to ethylene oxide followed by proton‐induced cyclisation provides the tetrahydrofuran 4a. The oxirane 6, which is formed by simple functional group interconversion, is opened by the diethylaluminium salt 10 of a propargylsilane. After catalytic hydrogenation and tosylation, fluoride‐induced cyclisation of the allylsilane 13 gives the target molecule 1b.
Enantiospecific synthesis of (2S,3S,5S)‐2‐acetamido‐2,4‐dideoxyhexopyranose (N‐acetyl‐4‐deoxy‐D‐mannosamine) from D‐glucose
Authors: Mulzer Johann , Seilz Carsten , Reutter Werner
Published: July 2007

A 14‐step enantiospecific total synthesis (overall yield 6%) of the title compound 1 from the known furanose 4 (derived from D‐glucose) is described.
Über Pyridinium‐N‐phenolat‐Betaine und ihre Verwendung zur Charakterisierung der Polarität von Lösungsmitteln, XVIII. Synthese und UV/Vis‐spektroskopische Eigenschaften eines negativ solvatochromen Pyridinium‐N‐thiophenolat‐Betainfarbstoffs
Authors: Reichardt Christian , Eschner Michael
Published: July 2007

Pyridinium N‐Phenoxide Betaines and Their Application for the Characterization of Solvent Polarities, XVIII. – Synthesis and UV/Vis Spectroscopic Properties of a Negatively Solvatochromic Pyridinium N‐Thiophenoxide Betaine Dye

Synthesis and UV/Vis spectroscopic properties of the negatively solvatochromic, relative to 1 homomorphic, thiobetaine dye 2 are described. The new thiobetaine 2 exhibits an even larger negative solvatochromism and thermochromism than the standard betaine dye 1, which has been used to establish an empirical scale of solvent polarity, the so‐called ET(30) scale. Surprisingly, there exists a linear correlation between the ETO(30) values of 1 and the ETS(30) values of 2 for both aprotic and protic solvents, despite of the fact that sulfur is usually known to act as worse hydrogen‐bond acceptor than oxygen. Possible reasons for this extraordinary behaviour of 2 are discussed. In contrast to 2, the sulfo‐substituted betaine dye 4 does not exhibit any solvatochromism.
Conversion of oleic acid to 17‐ and 18‐substituted stearic acid derivatives by way of the „acetylene zipper”︁
Authors: Augustin Kim E. , Schäfer Hans J.
Published: July 2007

Stearolic acid (2) was prepared from oleic acid (1) and converted to 4, 5, and 7 by way of the „acetylene zipper”︁ reaction. Compounds 5 and 7 were transformed to the (ω – 1) ketones 8 and 9 and dimerized by way of the Glaser coupling reaction to 11 and 12. At daylight, 12 polymerizes to a blue polymer.
Synthetic microbial chemistry, XXIV. Synthesis of antibiotic 1233A, an inhibitor of cholesterol biosynthesis
Authors: Mori Kenji , Takahashi Yoshio
Published: July 2007

A synthesis of 1233A [(2E,4E,7R,2′R,3′R)‐11‐[3′‐(hydroxymethyl)‐4′‐oxo‐2′‐oxetanyl]‐3,5,7‐trimethyl‐2,4‐undecadienoic acid (1a)] was achieved by employing (R)‐2‐hydroxymethyl‐3‐butenyl acetate (2a) and (R)‐citronellic acid (3) as chiral building blocks. The former was prepared by lipase‐mediated asymmetric hydrolysis of the corresponding diacetate.
Benzyl (R)‐ and (S)‐2‐tert‐butyl‐5‐oxo‐oxazolidine‐3‐carboxylate for convenient preparation of D‐ and L‐threonine analogs from aldehydes
Authors: Blaser Denis , Seebach Dieter
Published: July 2007

Lithium enolates of (R)‐ or (S)‐oxazolidinones 1 (specified in the title) are generated with lithium hexamethyldisilazanide (LHMDS) in THF at −75°C and added to aliphatic or aromatic aldehydes (products 2–18 of hydroxyalkylation, yields mostly over 80%, diastereoselectivities usually over 98%; Scheme 2). The adducts can be cleaved to give threonine analogs (19–32) under salt‐free conditions (H2/Pd‐C, then H2O and evaporation of the solvents, Scheme 3). In some cases, the primary adducts may cyclize with elimination of benzyl alcohol to give bicyclic carbamates 33 which, in turn, can be hydrolyzed to 5‐substituted trans‐2‐oxo‐1,3‐oxazolidine‐4‐carboxylic acids 34 (Scheme 4). – The essentially complete threo selectivity of the coupling step is proved by NMR spectroscopy and by chemical correlations. The stereochemical course of the reaction is opposite to that observed with carbocyclic enolates; possible reasons for this behavior are discussed (Scheme 5). – The starting material rac‐1, prepared from glycine, pivalaldehyde and benzyl chloroformate, is readily resolved by chromatography on preparative scale by using the stationary phase Chiraspher® and a Prepbar® system (Scheme 1); the undesired enantiomer may be recycled by thermal racemization (heating at reflux in CH3CN for 8 h).
Condensation of diglycolic acid dichloride with polyglycols, 5. An improved synthesis of cyclic polyether‐esters by cyclization
Authors: Erk Cakil
Published: July 2007

An improved synthesis of oligocyclic (ether‐ester)s by cyclization condensation of polyglycols with diglycolic acid dichloride in benzene/pyridine or dioxane/pyridine is reported.
Untersuchungen an 1,3‐Thiazinen, 44. Neuartige Umlagerungsreaktion von 3,3′‐Carbonylbis(tetrahydro‐2H‐1,3‐thiazin‐2‐thion) und 3,3′‐Carbonylbis(2‐thiazolidinthion)2)
Authors: Hanefeld Wolfgang , Von Gösseln Hans Joachim
Published: July 2007

Investigations of 1,3‐Thiazines, 44. – Novel Rearrangement of 3,3′‐Carbonylbis(tetrahydro‐2H‐1,3‐thiazine‐2‐thiozine) and 3,3′‐Carbonylbis(2‐thiazolidinethione)2)

2‐Thioxo‐1,3‐thiazine and ‐thiazolidine derivatives react with phosgen yielding N,N′‐carbonylbis(heterocycles) 3, 9, 11, 12. With excess of phosgen 3 and 9 gave a novel rearrangement to the 3,5‐bis(ω‐chloroalkyl)‐2,6‐dithioxo‐perhydro‐1,3,5‐thiadiazin‐4‐ones 8 and 10.
Short and stereoselective synthesis of (±)‐ibogamine via a Vinylsulfone intermediate, IV
Authors: Herdeis Claus , Hartke‐Karger Claudia
Published: July 2007

Ibogamine (11b) was synthesized starting from the vinyl sulfone 3. Addition of organocuprate reagents to 3 furnished 2a–d with high stereoselectivity. Only products from the syn addition of the cuprate reagents could be detected. Functional group transformations provided 7a,b the key intermediates for the synthesis of (±)‐21‐noribogamine (11a) and (±)‐ibogamine (11b).
Synthesis of rac‐allocoronamic acid hydrochloride
Authors: Marco José L. , Sánchez Belén , Fernández M. Dolores , Bernabé Manuel
Published: July 2007

A new method is reported for the synthesis of rac‐allocoronamic acid hydrochloride (5), from the readily available oxazolone 1 via the 1,3‐dehydro amino acid derivative 2, diazomethane addition, photolysis and acid hydrolysis.
Studies on Isocyanides and Related Compounds. Synthesis of Oxazole Derivatives via the Passerini Reaction
Authors: Bossio Ricardo , Marcaccini Stefano , Pepino Roberto
Published: July 2007

The reaction between arylglyoxals (1), cyclohexyl isocyanide, and aromatic carboxylic acids (2) affords N‐cyclohexyl‐2‐acyloxy‐3‐aryl‐3‐oxopropionic amides (3) which can be cyclized to N‐cyclohexyl‐2,4‐diaryl‐5‐oxazolecarboxamides (4).
Bausteine von Oligosacchariden, IC. Darstellung von synthetischen Antigenen der inneren Core‐Region von Lipopolysacchariden durch Copolymerisation mit Acrylamid
Authors: Paulsen Hans , Wulff Achim , Brenken Mathias
Published: July 2007

Building Units of Oligosaccharides, IC. – Preparation of Synthetic Antigens of the Inner Core Region of Lipopolysaccharides by Copolymerisation with Acrylamide

Besides L‐α‐D‐Hepp‐OAll (5), the following allyl glycosides with oligosaccharide structures of the inner core region of lipopolysaccharides have been synthesized: L‐α‐D‐Hepp‐(1→7)‐L‐α‐D‐Hepp‐OAll (19), L‐α‐D‐Hepp‐(1→3)‐L‐α‐D‐Hepp‐OAll (26), L‐α‐D‐Hepp‐(1→5)‐α‐Kdop‐OAll (31), L‐α‐D‐Hepp‐(1→5)‐β‐Kdop‐OAll (34), L‐α‐D‐Hepp‐(1→5)‐[α‐Kdop‐(2→4)]‐α‐Kdop‐OAll (48) and L‐α‐D‐Hepp‐(1→5)‐[α‐Kdop‐(2→4)]‐β‐Kdop‐OAll (39). All these compounds have been coupled with cysteamine to the spacer‐elongated derivatives 54b – 60b and finally converted into the acryloyl compounds 54c – 60c. The copolymerisation of 54c – 60c with acrylamide gave the polymers 54d – 60d, containing the above mentioned oligosaccharides as haptens in an antigenic form.
Synthesis of allopurinol and 4‐amino‐1H‐pyrazolo[3,4‐d]pyrimidine N1‐ and N2‐(β‐D‐arabinofuranosides)
Authors: Seela Frank , Winter Holger
Published: July 2007

Allopurinol and 4‐amino‐1H‐pyrazolo[3,4‐d]pyrimidine N1‐and N2‐(D‐arabinofuranosides) have been synthesized. Nucleobase anion glycosylation of 4‐methoxy‐1H‐pyrazolo[3,4‐d]‐pyrimidine (7) with the α‐D‐arabinofuranosyl chloride 6a proceeds stereoselectively and affords the N1‐(β‐D‐nucleoside) 8 as the main product (43% yield) together with the N2 isomer 10 (25% yield). The formation of the α anomer 9 (6% yield) results from the β‐D‐arabinofuranosyl chloride 6b being formed upon chlorination of the nitrobenzoate 5. Compounds were deprotected (11–13) and subjected to nucleophilic displacement reactions affording allopurinol and 8‐aza‐7‐deazaadenine N1‐and N2‐(arabinonucleosides) 1b, 2b, 3, and 4b. The anomeric configuration and the position of glycosylation have been established by 1D 1H‐NOE difference spectroscopy. Compound 3 has proved to be a substrate of adenosine deaminase with a half‐life 100‐fold longer than that of ara‐A.
An efficient synthesis of R3Si(CH2)n‐substituted acetylacetone derivatives
Authors: Urbaniak Wlodzimierz , Schubert Ulrich
Published: July 2007

An efficient synthesis of R3Si(CH2)3CH[C(O)Me]2 3 [R = Me, OR′] is described. The reaction of R3Si(CH2)3Cl 2 with the sodium of potassium salt of acetylacetonate (1) and 0.8–2 equivalents of NaI of KI in DMF, DMSO or NMP as a solvent gives the C‐ and O‐alkylation products R3Si(CH2)3CH[C(O)Me]2 3 and R3Si(CH2)3OC(Me)CHC(O)Me 4 in a 3:1 ratio and a 60–70% total yield. For R3SiCH2CH[C(O)Me]2 selectivity and yields are lower.
Synthesen mit aliphatischen Dialdehyden, XLV. Substituierte Glutaconaldehyd‐Derivate durch Vilsmeier‐Addition an 1‐Methoxy‐1‐buten‐3‐in, 1‐Methoxy‐1‐penten‐3‐in und 1‐(Dimethylamino)‐1‐buten‐3‐in und deren Reaktionen mit einigen Nucleophilen
Authors: Nolte Christian , Schäfer Gerhard , Reichardt Christian
Published: July 2007

Syntheses with Aliphatic Dialdehydes, XLV. – Substituted Glutaconaldehyde Derivatives by Vilsmeier Addition to 1‐Methoxy‐1‐buten‐3‐yne, 1‐Methoxy‐1‐penten‐3‐yne, and 1‐(Dimethylamino)‐1‐buten‐3‐yne and Their Reactions with Some Nucleophiles

3‐Halogeno‐substituted unsymmetrical pentamethinium salts 5, 7, 8, and 10 as well as 3‐halogeno‐substituted symmetrical vinamidinium salts 6, 9, and 11 are synthesized by addition of suitably substituted Vilsmeier reagents to 1‐methoxy‐1‐buten‐3‐yne (1). Analogous Vilsmeier additions to 1‐methoxy‐1‐penten‐3‐yne lead to 3‐halogen‐2‐methyl‐substituted unsymmetrical pentamethinium salts 13 and 14. Symmetrical 3‐methoxy‐and 3‐methylthio‐substituted vinamidinium salts 15 and 16 are observed by appropriate Vilsmeier additions to 1‐(dimethylamino)‐1‐buten‐3‐yne (4). Further 3‐substituted unsymmetrical and symmetrical pentamethinium salts are obtained by nucleophilic substitution at the C‐3 position of these salts, leading to 19–27. The [C4 + C1] pathway to 3‐substituted glutaconaldehyde derivatives represents a useful completion to their synthesis.
Natural Product Chemistry, 147. Synthesis of some coumarin derivatives
Authors: Reisch Johannes , Herath H. M. T. Bandara , Bergenthal Dieter , Kumar N. Savitri
Published: July 2007

Two naturally occurring coumarins, dihydrosuberenol (5) and (E)‐O‐ethylsuberenol (6), and another possible natural product (E)‐O‐methylsuberenol (7), were synthesized from (E)‐suberenol (1). The treatment of 1 with HBr gave the new menthadienediylbis(coumarin) 8.
Enantioselective synthesis of (S)‐(+)‐2‐tridecanol acetate, an aggregation pheromone component of Drosophila mulleri
Authors: Enders Dieter , Plant Andrew
Published: July 2007

The enantioselective synthesis of (S)‐(+)‐2‐tridecanol acetate [(S)‐6] (ee = 93.5%), an aggregation pheromone of Drosophila mulleri, is described. Key steps are the α‐alkylation of the propiophenone SAMP‐hydrazone (S)‐2 (de ≥ 96%) and the Baeyer‐Villiger reaction of the ketone (S)‐4.