bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of 4‐Alkoxy‐1,3‐oxazol‐5(2H)‐ones, Precursors of 1‐alkoxy substituted nitrile ylides
Authors: Bozhkova Nina , Heimgartner Heinz 
Published: December 2004

Abstract4‐Alkoxy‐1,3‐oxazol‐5(2H)‐ones of type 4 and 7 were synthesized by two different methods: oxidation of the 4‐(phenylthio)‐1,3‐oxazol‐5(2H)‐one 2a with m‐chloroperbenzoic acid in the presence of an alcohol gave the corresponding 4‐alkoxy derivatives 4, presumably via nucleophilic substitution of an intermediate sulfoxide (Scheme 2). The second approach is the BF3‐catalyzed condensation of imino‐acetates of type 6 and ketones (Scheme 3). The yields of this more straightforward method were modest due to the competitive formation of 1,3,5‐triazine tricarboxylate 8. At 155°, 1,3‐oxazol‐5(2H)‐one 7b underwent decarboxylation leading to an alkoxy‐substituted nitrile ylide which was trapped in a 1,3‐dipolar cycloaddition by trifluoro‐acetophenone to give the dihydro‐oxazoles cis‐ and trans‐9 (Scheme 4). In the absence of a dipolarophile, 1,5‐dipolar cyclization of the intermediate nitrile ylide yielded isoindole derivatives 10 (Schemes 4 and 5).
Festkörper‐Polymerisation eines ‘Push‐Pull’‐Diacetylens
Authors: Galli Roberto , Neuenschwander Markus , Engel Peter 
Published: December 2004

Solid‐State Polymerisation of a ‘Push‐Pull’‐DiacetyleneSolid‐state polymerisation of ‘push‐pull’‐diacetylene 5‐(diphenylamino)‐1‐phenylpenta‐2,4‐diyn‐1‐one (1d), initiated by heating of crystals of 1d at 90°, gives ‘push‐pull’ poly‐diacetylene 2d. X‐Ray results and spectroscopic data of monomer 1d as well as of polymer 2d are discussed.
Synthesis of cis and trans Whisky and Cognac lactones by the regiocontrolled alkylation of 2‐(trimethylsiloxy)furan
Authors: Jefford Charles W. , Sledeski Adam W. , Boukouvalas John 
Published: December 2004

AbstractThe racemic cis‐ and trans‐5‐butyltetrahydro‐4‐methylfuran‐2‐ones ( = whisky lactones) and their higher homologues tetrahydro‐4‐methyl‐5‐pentylfuran‐2‐ones ( = cognac lactones) have been prepared in 2–3 steps from 2‐(trimethylsiloxy)furan. Regioselective alkylation of the latter afforded the 5‐butyl‐ and 5‐pentylfuran‐2(5H)‐ones which served as precursors for the stereocontrolled construction of either diastereoisomer of the beverage lactones. The structure and tautomerization of the diazomethane adducts of these 5‐alkylfuran‐2(5H)‐ones are also described.
[4 + 2]‐Cycloadditionen von α, β‐ ungesättigten hydrazonen. Teil3. Isothiazolo[4,5‐b]pyridin‐3(2H)‐on‐1,1‐dioxide (= 4‐azasaccharine)
Authors: Waldner Adrian 
Published: December 2004

[4 + 2] Cycloaddition of α, β‐Unsaturated Hydrazones: Isothlazolo[4,5‐b]pyridin‐3(2H)‐on 1,1‐Dioxides (= 4‐Azasaccharine Derivatives)The [4 + 2] cycloaddition of α, β ‐unsaturated hydrazones of type 1 (1‐azabuta‐1,3‐dienes) with isothiazol‐3(2H)‐on 1,1‐dioxide derivatives 10 affords, depending on the solvent used, picolinamides 15 or 17, 4,7‐dihydro‐4‐azasaccharine 14 or 4‐azasaccharine derivatives 16 (Scheme 4). The course of the reaction is mainly influenced by the substituent R of the dienophile 10.
Catalytic effect of tetrabutylammonium fluoride in the preparation of secoribo‐nucleosides
Authors: Hakimelahi Gholam H. , Khalafi‐Nezhad Ali 
Published: December 2004

AbstractA general and rapid procedure is developed for the preparation of secoribo‐nucleoside analogues. Bu4NF has a marked effect on the condensation of guanine (5) with 2‐(chloromethoxy)ethyl benzoate (2) or 1‐halo‐2‐(chloromethoxy)ethanes 12 and 16. Condensation and deprotection of the acyl protecting group and nucleophilic displacement of the halogen atoms to yield 9‐[(2‐hydroxyethoxy)methyl] guanine (9) occurred in one step.
New aromatic musk odorants: Design and synthesis
Authors: Fehr Charles , Galindo José , Haubiichs Rolf , Perret Roland 
Published: December 2004

AbstractBy appropriate structural modification of known musk odorants, new strong musk odorants have been discovered. Incorporation of supplementary CH3 or CH2 groups into the basic musk skeleton of type G only slightly modifies the global shape of the molecule but leads to densely packed structures of enhanced lipophilicity. For the construction of these highly substituted 1,2,3,4‐tetrahydronaphthalenes, new annulation sequences (intramolecular mono‐ and dialkylations; see Schemes 3,6, and 8) have been developed and, in certain cases, the design of the target molecules was dictated by both structure‐activity‐relationship and synthetic considerations (e.g. 46 and 47, Scheme 6). This work also presents an original solution to an analytical problem: the distinction between a C2‐ and a Cs‐symmetrical aromatic hydrocarbon (viz. 71 and 72) by conversion into a [Cr(CO)3arene]complex.
Synthesis and Structure of a New Type of Chiral Organoiron and Organoruthenium Complexes
Authors: Adams Christoph M. , Hafner Andreas , Koller Markus , Marcuzzi Alessandro , Prewo Roland , Solana Isabel , Vincent Beverly , von Philipsborn Wolfgang 
Published: December 2004

AbstractThe synthesis of 36 [Fe(CO)2L1(η4‐diene)], three [Fe(CO)2L1(η4‐encne)], and five [Ru(CO)2L1(η4‐diene)] complexes (L1 = Ph3P, Et3P, (EtO)3P, (MeO)3p, C6H11NC) by thermal, selective CO ligand displacement in the corresponding tricarbonyl precursor complexes is described. In a second step, photochemical CO displacement by another phosphorus ligand L2 leads to a new type of η4‐diene complexes with a centre of chirality at the metal atom (Fe, Ru). 23 Fe and three Ru complexes of this type have been prepared and characterized. In the case of complexes with unsymmetrical dienes, racemic diastereoisomers are formed which can be separated by chromatographic methods. The molecular structures of [Fe(CO)(Ph3P)((MeO)3P)(buta‐1,3‐diene)] (52), [Fe(CO)(Ph3P)((MeO)3P)(isoprene)] (58) and [Fe(CO)(Et3P)(EtO)3P(hexa‐2,4‐dienal)] (62a) were determined by X‐ray diffraction. All complexes were investigated by 13C‐, 31P‐ and, in part, 1H‐NMR spectroscopy. At low temperatures, conformational isomers (rotamers) can be differentiated which probably arise from ψ rotation at the coordinated metal centre.
Synthesis of Peptides Containing α,α‐Disubstituted α‐Amino Acids by the Azirine/Oxazolone Method: The (12–20)‐Nonapeptide of the Ionophore Alamethicin
Authors: Wipf Peter , Heimgartner Heinz 
Published: December 2004

AbstractThe (12–20)‐nonapeptide Z‐Leu‐Aib‐Pro‐Val‐Aib‐Aib‐Glu (OBzl)‐Gln‐Pheol (10) of the ionophor alamethicin was synthesized by a new strategy, using 3‐amino‐2,2‐dimethyl‐2H‐azirines 2 as synthons for the α‐aminoisobutyric acid (Aib) moieties.
Synthesis of Derivatives of (1R*,10aR*)‐1‐Azido‐10‐benzylidene‐4‐(diethylphosphono)‐1,2,10,10a‐tetrahydro‐2‐oxo‐4H‐azeto[1,2‐a]pyrido[1,2‐d]pyrazin‐9‐ylium Bromide
Authors: Hakimelahi Gholam H. , Sardarian Ali R. 
Published: December 2004

AbstractThe synthesis of some derivatives of the title compound VI is described. Bromination of diethyl (cis‐3‐azido‐2‐oxo‐4‐styrylazetidin‐1‐yl)(pyridin‐2‐yl)methylphosphonate (6) in MeOH gave tricyclic β‐lactam 7, while similar bromination of diethyl (cis‐3‐azido‐2‐oxo‐4‐vinylazetidin‐1‐yl)(pyridin‐2‐yl)methylphosphonate (9) afforded tri‐cyclic β‐lactam 10. Mechanisms for these transformations are proposed (Schemes 1 and 2).
trans‐Disubstituted Cyclohexadienes via Sequential Addition of a Carbon Nucleophile and an Electrophile to (η6‐Benzene)tricarbonylchromium: Scope of Carbon Electrophiles
Authors: Kündig E. Peter , Cunningham Allan F. , Paglia Patrick , Simmons Dana P. , Bernardinelli Gérald 
Published: December 2004

AbstractA regio‐ and stereoselective route from benzene to trans‐disubstituted cyclohexadienes via complexation of the arene to the tricarbonylchromium group is reported. The key step involves an alkylation/carbonylation sequence of the anionic tricarbonyl (η5‐cyclohexadienyl)chromium complex (3) which is readily obtained by the addition of 2‐lithio‐2‐methyldithiane (2) to (η6‐benzene)tricarbonylchromium (1; cf. Scheme 6). In situ reaction of 3 with alkyl halides (in THF, THF/HMPA, THF/DMPU), followed by oxidation (I2, Ce(IV)) or ligand exchange (CO, Ph3P, Et3N) produced, with complete stereo‐ and regioselectivity, trans‐5,6‐disubstituted cyclohexadienes (15 examples). The cyclohexadiene substituent originating from the alkyl halide in all cases is an acyl group which shows that CO insertion into the metal–alkyl bond precedes reductive elimination to form the cyclohexadiene product. When, in the reaction of 3 with Mel, NHS3 was used to induce carbonylation und decornplexation, the isomerized, conjugated 1,4‐cyclohexadiene 13 was obtained almost exclusively. The electrophile selectivity in the reactions with 3 is consistent with a nucleophilic, SN2‐like mechanism with a high preference for primary iodides. Chloride, ketone, and ester functions in the electrophile are unreactive and are tolerated; a primary alkyl iodide reacted selectively in the presence of a secondary iodide. In one case, the trans‐configuration in a cyclohexadiene product 7 was demonstrated by the Diels‐Alder reaction with maleic anhydride. High facial selectivity was observed in this reaction giving a single diastereoisomer resulting from endo‐addition of the dienophile to the diene face carrying the acyl group. The anionic intermediate 3 was trapped with Ph3SnCl, and an X‐ray analysis of the resulting cyclohexadienyl [Cr(CO)3(R)] complex 15 provides evidence for electrophile addition to the metal. In the solid state, the Ph3Sn group in 15 is trans‐configurated to the dithianyl substituent. The ready access to [Cr(arene)(CO)3] complexes, the high selectivity of the reactions reported here and the mild decomplexation provide rapid access to Cyclohexadienes that possess functionality and are attractive for further transformation.
A CD‐Spectroscopic Alternative to Methylation Analysis of Oligosaccharides: Reference Spectra for Identification of Chromophoric Glycopyranoside Derivatives
Authors: Wiesler William T. , Berova Nikolina , Ojika Makoto , Meyers Harold V. , Chang Mayland , Zhou Peng , Lo Lee‐Chiang , Niwa Masatake , Takeda Reiji , Nakanishi Koji 
Published: December 2004

AbstractA microscale method for identifying the monosaccharide units and their linkages in oligosaccharides is presented. Sugar components are identified by UV and CD spectroscopy of chromophoric degradation products. CD spectral data for approximately 150 different glycopyranoside components are provided for use as reference spectra in the identification of unknown derivatives. Procedures for the conversion of oligosaccharides to monosaccharide subunits bearing 4‐bromobenzoate and 4‐methoxycinnamate chromophores have been developed based on acetolysis/bromination reactions for glycosidic cleavage of per (bromobenzoylated) oligosaccharides. The method offers an alternative means to conventional methylation analysis of oligosaccharides.
Reaktionen von 3‐(Dimethylamino)‐2H‐azirinen mit 1,3‐Benzoxazol‐2(3H)‐thion
Authors: Ametamey Simon M. , Heimgartner Heinz 
Published: December 2004

Reaction of 3‐(Dimethylamino)‐2H‐azirines with 1,3‐Benzoxazole‐2(3H)‐thioneThe reaction of 3‐(dimethylamino)‐2H‐azirines 2 with 1,3‐benzoxazole‐2(3H)‐thione (5), which can be considered as NH‐acidic heterocycle (pKaca. 7.3), in MeCN at room temperature, leads to 3‐(2‐hydroxyphenyl)‐2‐thiohydantoins 6 and thiourea derivatives of type 7 (Scheme 2). A reaction mechanism for the formation of the products via the crucial zwitterionic intermediate A′ is suggested. This intermediate was trapped by methylation with Mel and hydrolysis to give 9 (Scheme 4). Under normal reaction conditions, A′ undergoes a ring opening to B which is hydrolyzed during workup to yield 6 or rearranges to give the thiourea 7. A reasonable intermediate of the latter transformation is the isothiocyanate E (Scheme 3) which also could be trapped by morpholine. In i‐PrOH at 55–65° 2a and 5 react to yield a mixture of 6a, 2‐(isopropylthio)‐1,3‐benzoxazole (12), and the thioamide 13 (Scheme 5). A mechanism for the surprising alkylation of 5 via the intermediate 2‐amino‐2‐alkoxyaziridine Fis proposed. Again via an aziridine, e.g. H (Scheme 6), the formation of 13 can be explained.
Homogeneous and heterogeneous asymmetric reactions. Part 5. Diastereoselective and enantioselective hydrogenation of cyclic β‐keto esters on modifiedRaney‐nickel catalysts
Authors: Wittmann Gyula , Göndös György , Bartók Mihály 
Published: December 2004

AbstractThe hydrogenations of methyl 2‐oxoeyclopentanecarboxylate (1), ethyl 2‐oxocyelohexanecarboxylate (3), and 2‐methylcyclohexanone (5) on unmodifiedRaney‐Ni catalyst lead predominately to the formation of thecis‐hydroxy diastereoisomers of2,4, and6, respectively (Scheme 2). In the asymmetric hydrogenations on catalysts modified with chiral tartaric acid ((R,R)‐C4H6O6/Raney‐Ni and (R,R)‐C4H6O6/NaBr/Raney‐Ni), the predominance of thecis‐isomer increases significantly. The hydrogenations of β‐keto esters1and3proceed with an enantioselectivity of 10–15% on the modified catalysts, while the similar hydrogenation of5yields optically inactive6. The (1S,2R)‐enantiomers of thecis‐isomers of2and4are formed in larger quantity, whereas the (lR,2R)‐enantiomers of the correspondingtrans‐isomers predominate (Scheme 1). The enantioselective formation oftrans‐2andtrans‐4can be interpreted mainly in terms of the asymmetric hydrogenation of cyclic β‐keto esters through the keto form, while that of the correspondingcis‐hydroxy esters proceeds through the enol form.
Technical Procedures for the Syntheses of Carotenoids and Related Compounds from 6‐Oxo‐isophorone: Syntheses of (3R,3′R)‐Zeaxanthin. Part II
Authors: Soukup Milan , Widmer Erich , Lukáč Theodor 
Published: December 2004

AbstractStarting from the readily available, optically active (4R)‐hydroxy‐2,2,6‐trimethylcyclohexanone (2), a new technical synthesis of (3R,3′R)‐zeaxanthin is described. According to a completely new C9+C2+C4 = C15 scheme, the ketone 2 was protected, ethynylated with Li‐acetylide, and the C11‐intermediate 6 was acetylated, followed by dehydration. The product 10 was protected, deprotonated, and subsequently reacted with methyl vinyl ketone to provide the C15‐propargylate 13. Reduction in situ of 13 with Vitride yielded the olefinic C15‐alcohol 11 which was transformed into the known C15‐Wittig salt 3. A double Wittig reaction of this salt with the C10‐dialdehyde 4 afforded nature‐identical zeaxanthin (1).
Structure and Synthesis of (±)‐Caudoxirene, a New Spermatozoid‐Releasing and ‐Attracting Pheromone from the Marine Brown Alga Perithalia caudata (Phaeophyceae, Sporochnales). Part V
Authors: Wirth Dieter , Boland Wilhelm 
Published: December 2004

AbstractCis‐3‐(trans‐1,2‐Epoxybut‐3‐enyl)‐4‐vinylcyclopentene ((±)‐4, caudoxirene) is a new gamete‐releasing and gamete‐attracting pheromone from the marine brown alga Perithalia caudata (Sporochnales). The key step of its synthesis is the diastereoselective alkylation of the aldehyde 8 with the [(phenylthio)allyl]titanium reagent 9 to yield the erythro‐β‐hydroxy sulfide 10 which affords 4 on sequential treatment with Me3O·BF4 and aq. NaOH. The lowest effective concentration of (±)‐4 for gamete‐release is found at 1.4 × 10−11 mol/l seawater.
Synthesis and biological evaluation of 14‐alkoxymorphinans. Part 7. 14,14′‐dimethoxy analogues of norbinaltorphimine: Synthesis and determination of their χ opioid antagonist selectivity
Authors: Schmidhammer Helmut , Ganglbauer Ernst , Mitterdorfer Jörg , Rollinger Judith M. , Smith Colin F. C. 
Published: December 2004

AbstractThe bimorphinans 6 and 7 have been prepared from 14‐O‐methylnaloxone (2) and 14‐O‐methylnaltrexone (3), respectively. The known compounds 2 and 3 were synthesized by a different route than the route described. Bimorphinan 7 possessed a similar χ receptor affinity to norbinaltorphimine (1) but had a reduced selectivity due to marked increases in μ and δ receptor affinity. Bimorphinan 6 was both a less selective and less potent χ antagonist than 1.
Stereoselective Synthesis of the C(19)‐to‐C(27) Segment of Rifamycin S
Authors: Born Marco , Tamm Christoph 
Published: December 2004

AbstractThe synthesis of diester 3, a synthon for the C(19)‐to‐C(27) segment of rifamycin S (1), is described, starting from the meso‐diester 4 (Schemes 2 and 3). Inversion of the configuration at the later C(23) and two aldol condensations with the lithium enolate 18 of 2,6‐dimethylphenyl propionate each producing two new chiral centres of threo‐configuration, led to the desired diester 3. The absolute configuration of the new chiral centres was proven by a single X‐ray analysis of intermediate 19 (Fig.) and by converting diester 3 into meso‐diester 25.
1H‐Phenalen‐1‐one: Photophysical Properties and Singlet‐Oxygen Production
Authors: Oliveros Esther , Suardi‐Murasecco Patricia , Aminian‐Saghafi Taraneh , Braun André M. , Hansen Hans‐Jürgen 
Published: December 2004

AbstractThe efficiency of aromatic ketones as singlet‐oxygen (1O2(1Δg)) sensitizers can vary considerably with the electronic configuration of their lowest triplet state and the solvent used. Near‐infrared measurements of tie luminescence of singlet oxygen have shown that the quantum yield of singlet‐oxygen production (ΦΔ) by 1H‐phenalen‐1‐one (1) is close to unity in both polar (ΦΔ= 0.97±0.03 in methanol) and non‐polar solvents (ΦΔ= 0.93±0.04 in benzene). Analysis of the absorption spectra of the ground state and phosphorescence measurements show that the lowest singlet and triplet states have dominant π, π* electronic configurations. The quantum yield of intersystem crossing (ΦISC) of1, determined by laser flash photolysis (partial‐saturation method), is equal to unity. In comparison with other aromatic ketones, these parameters are important for the discussion of the surprisingly high ΦISCof1and the efficient energy transfer from its triplet state to molecular oxygen. The 1H‐phenalen‐1‐one (1), being one of the most efficient singlet‐oxygen sensitizers in both polar and non‐polar media, could be used as a reference sensitizer, in particular in the area of relatively high energies of excitation.
Synthesis of Aristotelia‐Type Alkaloids. Part VIBiomimetic Synthesis of (+)‐Aristofruticosine
Authors: Beerli René , Borschberg Hans‐Jürg 
Published: December 2004

Abstract(S)‐Perilla alcohol (5) was transformed into (S)‐7‐(phenylthio)‐p‐menth‐1‐en‐8‐amine (11) in five steps. Condensation of this building block with 1‐(4‐methoxyphenylsulfonyl)‐1H‐indole‐3‐acetaldehyde (12) led to the expected imine 15 which cyclized in 54% yield to protected 20‐(phenylthio)hobartine 16 upon exposure to anh. HCOOH. Treatment of this intermediate with an alkylating reagent led to (+)‐aristofruticosine protected in the indole moiety via an intramolecular, allylic nucleophilic displacement reaction. Subsequent reductive removal of the protecting group completed the first synthesis of the Aristotelia alkaloid (+)‐aristofruticosine ((+)‐4). This straightforward synthesis confirmed the tentative structure (+)‐4, proposed by Bick and Hai, and established the hitherto unknown absolute configuration of this metabolite.
C2‐Symmetric 4,4′,5,5′‐Tetrahydrobi(oxazoles) and 4,4′,5,5′‐Tetrahydro‐2,2′‐methylenebis[oxazoles] as Chiral Ligands for Enantioselective Catalysis Preliminary Communication
Authors: Müller Dieter , Umbricht Gisela , Weber Beat , Pfaltz Andreas 
Published: December 2004

AbstractThe synthesis of a series of enantiomerically pure, C2‐symmetric 4,4′,5,5′‐tetrahydro‐2,2′‐methylenebis[oxazoles] and 4,4′,5,5′‐tetrahydro‐2,2′‐bi(oxazoles) is reported. Copper complexes with anionic tetrahydromethylenebis[oxazole] ligands are efficient catalysts for the enantioselective cyclopropane formation from olefins and diazo compounds (up to 96% ee in the reaction of styrene with menthyl diazoacetate). Tetrahydrobi(oxazole)iridium(I) complexes were found to catalyze transfer hydrogenations of aryl alkyl ketones with i‐PrOH (up to 91% ee). Tetrahydrobi(oxazole)palladium complexes can be used as enantioselective catalysts for allylic nucleophilic substitution (up to 77% ee in the reaction of PhCHCHCH(OAc)Ph with NaHC(COOMe)2).
Electronic and Conformational Effects on the Lipophilicity of Isomers and Analogs of the Neurotoxin 1‐Methyl‐4‐phenylpyridinium (MPP+)
Authors: Altomare Cosimo , Carrupt Pierre‐Alain , El Tayar Nabil , Testa Bernard , Nagatsu Toshiharu 
Published: December 2004

AbstractA number of isomers and analogs of the neurotoxin 1‐methyl‐4‐phenylpyridinium (MPP+) were examined for their lipophilic behavior. Their partition coefficients in the 1‐octanol/H2O system were measured by centrifugal partition chromatography (CPC), which, being much faster and markedly more precise than the classical shake‐flask method, proved a very promising alternative for assessing lipophilicity. A smaller‐than‐expected lipophilicity was shown by the ortho‐isomer of MPP+ (M2PP+) and is explained in terms of electronic effects and rigidity, as revealed by UV and NMR spectroscopy, and conformational analysis. Implications of lipophilicity in modulating the in vivo dopaminergic neurotoxicity of the examined compounds are also discussed.
Analogues of Sialic Acids as Potential Sialidase Inhibitors. Synthesis of C6 and C7 Analogues of N‐Acetyl‐6‐amino‐2,6‐dideoxyneuraminic Acid
Authors: Glänzer Brigitte I. , Györgydeák Zoltan , Bernet Bruno , Vasella Andrea 
Published: December 2004

AbstractThe piperidines 12–18, piperidmose analogues of Neu5Ac (1) with a shortened side chain, were synthesized from N‐acetyl‐D‐glucosamine via the azidoalkene 32 and tested as inhibitors of Vibrio cholerae sialidase. Deoxygenation at C(4) of the uronate 22, obtained from the known D‐GlcNAc derivative 20, was effected by β‐elimination (→ 23), exchange of the AcO at C(3) with a (t‐Bu)Me2SiO group and hydrogenation (→ 26; Scheme 1). Chain extension of 26 by reaction with Me3SiCH2MgCl gave the D‐ido‐dihydroxysilane 28, which was transformed into the unsaturated L‐xylo‐mesylate 29 and further into the L‐lyxo‐alcohol 30, the mesylate 31, and the L‐xylo‐azide 32. The derivatives 29–31 prefer a sickle zig‐zag and 32 mainly an extended zig‐zag conformation (Fig. 2). The piperidinecarboxylate 15 was obtained from 32 by ozonolysis (→ 33), intramolecular reductive animation (→ 34), and deprotection, while reductive animation of 34 with glycolaldehyde (→ 35) and deprotection gave 16 (Scheme 2). An intramolecular azide‐olefin cycloaddition of 32 yielded exclusively the fused dihydrotriazole 36, while the lactone 39 did not cyclize (Scheme 3). Treatment of 36 with AcOH (→ 37) followed by hydrolysis (→ 38) and deprotection led to the amino acid 18. To prepare the (hydroxymethyl)piperidinecarboxylates 12 and 17, 32 was first dihydroxylated (Scheme 4). The L‐gluco‐diol 40 was obtained as the major product, in agreement with Kishi's rule. Silylation of 40 (→ 42), oxidation with periodinane (→ 44), and reductive animation gave the L‐gluco‐piperidine 45. It was, on the one hand, deprotected to the amino acid 12 and, on the other hand, N‐phenylated (→ 46) and deprotected to 17. While 45 and 12 adopt a 2C5 conformation, the analogous N‐Ph derivatives 46 and 17 adopt a 5C2 and a B3,6 conformation, respectively, on account of the allylic 1,3‐strain. The conformational effects of this 1,3‐strain are also evident in the carbamate 47, obtained from 45 (Scheme 5), and in the C(2)‐epimerized bicyclic ether 48, which was formed upon treatment of 47 with (diethylamino)sulfur trifluoride (DAST). Fluorination of 40 with DAST (→ 49) followed by treatment with AcOH led to the D‐ido‐fluorohydrin 50. Oxidation of 50 (→ 51) followed by a Staudinger reaction and reduction with NaBH3CN afforded the (fluoromethyl)piperidine 52, while reductive amination of 51 with H2/Pd led to the methylpiperidine 55, which was similarly obtained from the keto tosylate 54 and from the dihydrotriazole 36. Deprotection of 52 and 55 gave the amino acids 13 and 14, respectively. The aniline 17 does not inhibit V. cholerae sialidase; the piperidines 12–16 and 18 are weak inhibitors, evidencing the importance of an intact 1,2,3‐trihydroxypropyl side chain.