bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Novel Three‐Dimensional Metal‐Organic Framework Constructed from Two‐Dimensional Interpenetrating Layers Based on Trinuclear Cobalt Clusters: [Co3(btec)(C2O4)(H2O)2]n
Authors: Li Yang‐Guang , Hao Na , Wang En‐Bo , Lu Ying , Hu Chang‐Wen , Xu Lin 
Published: July 2003

AbstractA novel coordination polymer [Co3(btec)(C2O4)(H2O)2]n (1; btec = 1,2,4,5‐benzenetetracarboxylate) has been hydrothermally synthesized and characterized by IR, XPS, XRPD, TG analysis and single‐crystal X‐ray diffraction. The structural analysis reveals that 1 exhibits a new three‐dimensional metal‐organic framework constructed from two‐dimensional parallel interpenetrating networks based on trinuclear cobalt cluster building blocks. Such interpenetrating composite networks in 1 represent the first example in the {M‐btec} (M = transition metal) system. Variable‐temperature magnetic susceptibility measurements indicate an antiferromagnetic behavior in 1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Blue to Red Fluorescent Emission Tuning of a Cadmium Coordination Polymer by Conjugated Ligands
Authors: Zhang Jing , Xie Yong‐Rong , Ye Qiong , Xiong Ren‐Gen , Xue Ziling , You Xiao‐Zeng 
Published: July 2003

AbstractThe hydrothermal hydrolysis reactions of Cd(ClO4)2·(6H2O) with 4‐[2‐(2‐pyridyl)ethenyl]benzonitrile (2‐PEBN) and 2‐[2‐(4‐cyanophenyl)ethenyl]‐8‐quinolinol (2‐CEQH) afforded two coordination polymers aquabis{4‐[2‐(2‐pyridyl)ethenyl]benzoate}cadmium(II) (1) and 2‐[2‐(4‐carboxylatophenyl)ethenyl]‐8‐quinolinolate(pyridine)cadmium(II) (2), respectively. Complexes 1 and 2 display strong blue and red fluorescent emission, respectively. Both 1 and 2 have a 2‐D grid framework containing a dimer as the corner unit. Crystal data for 1: monoclinic, P21/c, a = 15.2411(2), b = 19.8651(2), c = 15.6929(1) Å, α = β = 90, γ = 96.961(1)°; for 2: monoclinic, P21/c, a = 11.9219(1), b = 8.9515(1), c = 18.8204(1)Å, α = γ = 90.00, β = 104.372(1)°. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Im Stress werden Pilze und Pflanzen Partner
Authors: Bothe Hermann , Hildebrandt Ulrich 
Published: July 2003

Abstract80 Prozent aller Pflanzen leben in einer Symbiose mit Mykorrhiza‐Pilzen. Die molekularen Grundlagen dieser Lebensgemeinschaft stehen im Mittelpunkt eines DFG‐Schwerpunktprogramms
Im Blickpunkt: Ein Hauch von Nichts
Authors: Greiner Andreas , Steinhart Martin , Wendorff Joachim H. , Wehrspohn Ralf 
Published: July 2003

AbstractIn der Nanowelt spielen röhrenförmige Objekte eine besondere Rolle. Um Nanoröhrchen herzustellen, werden neue Präparationsverfahren entwickelt, die Grundlagen für eine Vielzahl technischer Anwendungen legen
Ultrafast Electron Diffraction (UED)
Authors: Srinivasan Ramesh , Lobastov Vladimir A. , Ruan Chong‐Yu , Zewail Ahmed H. 
Published: July 2003

AbstractWith properly timed sequences of ultrafast electron pulses, it is now possible to image complex molecular structures in the four dimensions of space and time with resolutions of 0.01 Å and 1 ps, respectively. The new limits of ultrafast electron diffraction (UED) provide the means for the determination of transient molecular structures, including reactive intermediates and non‐equilibrium structures of complex energy landscapes. By freezing structures on the ultrafast timescale, we are able to develop concepts that correlate structure with dynamics. Examples include structure‐driven radiationless processes, dynamics‐driven reaction stereochemistry, pseudorotary transition‐state structures, and non‐equilibrium structures exhibiting negative temperature, bifurcation, or selective energy localization in bonds. These successes in the studies of complex molecular systems, even without heavy atoms, and the recent development of a new machine devoted to structures in the condensed phase, establish UED as a powerful method for mapping out temporally changing molecular structures in chemistry, and potentially, in biology. This review highlights the advances made at Caltech, with emphasis on the principles of UED, its evolution through four generations of instrumentation (UED‐1 to UED‐4) and its diverse applications.
Enantioselective Preparation of 2‐Aminomethyl Carboxylic Acid Derivatives: Solving the β2‐Amino Acid Problem with the Chiral Auxiliary 4‐Isopropyl‐5,5‐diphenyloxazolidin‐2‐one (DIOZ). Preliminary Communication
Authors: Seebach Dieter , Schaeffer Laurent , Gessier François , Bindschädler Pascal , Jäger Corinna , Josien Delphine , Kopp Sascha , Lelais Gérald , Mahajan Yogesh R. , Micuch Peter , Sebesta Radovan , Schweizer Bernd W. 
Published: July 2003

AbstractMultigram amounts of suitably protected β2‐amino acids with 17 of the 20 proteinogenic side chains are prepared by diastereoselective reactions of Li, B, or Ti enolates of the corresponding 3‐acyl‐4‐isopropyl‐5,5‐diphenyloxazolidin‐2‐ones (acyl‐DIOZ; 1) with appropriate electrophiles (amidomethylation, hydroxyalkylation, (benzyloxycarbonyl)methylation) in yields of 55–90% and with diastereoselectivities of 80 to >97% (Scheme). The primary products 2–8 thus obtained are converted to protected β2‐amino acids by standard procedures (Table 1). Many of the DIOZ derivatives are highly crystalline compounds (31 X‐ray crystal structures in Table 2). The chiral auxiliary DIOZ, readily prepared in either enantiomeric form, is recovered with high yield.
Synthesis and CD Spectra of Fluoro‐ and Hydroxy‐Substituted β‐Peptides
Authors: Gessier François , Noti Christian , Rueping Magnus , Seebach Dieter 
Published: July 2003

Abstractβ‐Amino acids 1–3 with OH and F substituents in the α‐position have been prepared (Scheme) from the natural (S)‐α‐amino acids alanine, valine, and leucine, and incorporated into β‐hexa‐ and β‐heptapeptides 4–12. The peptide syntheses were performed according to a conventional solution strategy (Boc/Bn protection) with fragment coupling. The new β‐peptides with (series a) and without (series b) terminal protection were isolated in HPLC‐pure form and characterized by NMR spectroscopy and MALDI mass spectrometry. The chemical properties as well as the patterns of the CD spectra (Figs. 3–5) depend upon constitution (OH, F, F2 substitution) and configuration (l or u) of the amino acid residues, upon the total number of OH and F substituents in the peptide chain, and upon the solvent used (H2O, MeOH, CF3CH2OH, (CF3)2CHOH). No reliable clues regarding the structures can be obtained from these CD spectra. Only a full NMR analysis will be able to answer the questions: a) with which known secondary structures (Figs. 1 and 2) of β‐peptides are the OH and F derivatives compatible? b) Are new secondary structures enforced by the polar and/or H‐bonding backbone substituents? Furthermore, the β‐peptides described here will enable us to study changes in chemical, enzymatic, and metabolic stability, and in physiological properties caused by the heteroatoms.
Synthesis and Conformational Analysis of Macrocyclic Dilactones Mimicking the Pharmacophore of Aplysiatoxin
Authors: Knust Henner , Hoffmann Reinhard W. 
Published: July 2003

AbstractA small number of macrocyclic dilactones of type 3, i.e., 9, 10, 11, and epi‐11, comprising a 3,4‐dihydroxypentanoic acid unit, the pharmacophore of aplysiatoxin, and a conformationally preorganized ω‐hydroxynonanoic acid unit were synthesized. Conformational analysis – based on 2J and 3J NMR coupling constants – of the dihydroxypentanoyl part of these macro‐dilactones indicates the extent to which a conformation induction across the macro‐dilactone ring occurs from the stereogenic centres implemented in the ω‐hydroxynonanoic acid part.
Synthesis and α‐Mannosidase Inhibitory Evaluation of (2R,3R,4S)‐ and (2S,3R,4S)‐2‐(Aminomethyl)pyrrolidine‐3,4‐diol Derivatives
Authors: Popowycz Florence , Gerber‐Lemaire Sandrine , Rodriguez‐García Eliazar , Schütz Catherine , Vogel Pierre 
Published: July 2003

AbstractThe synthesis of 46 derivatives of (2R,3R,4S)‐2‐(aminomethyl)pyrrolidine‐3,4‐diol is reported (Scheme 1 and Fig. 3), and their inhibitory activities toward α‐mannosidases from jack bean (B) and almonds (A) are evaluated (Table). The most‐potent inhibitors are (2R,3R,4S)‐2‐{[([1,1′‐biphenyl]‐4‐ylmethyl)amino]methyl}pyrrolidine‐3,4‐diol (3fs; IC50(B)=5 μM, Ki=2.5 μM) and (2R,3R,4S)‐2‐{[(1R)‐2,3‐dihydro‐1H‐inden‐1‐ylamino]methyl}pyrrolidine‐3,4‐diol (3fu; IC50(B)=17 μM, Ki=2.3 μM). (2S,3R,4S)‐2‐(Aminomethyl)pyrrolidine‐3,4‐diol (6, RH) and the three 2‐(N‐alkylamino)methyl derivatives 6fh, 6fs, and 6f are prepared (Scheme 2) and found to inhibit also α‐mannosidases from jack bean and almonds (Table). The best inhibitor of these series is (2S,3R,4S)‐2‐{[(2‐thienylmethyl)amino]methyl}pyrrolidine‐3,4‐diol (6o; IC50(B)=105 μM, Ki=40 μM). As expected (see Fig. 4), diamines 3 with the configuration of α‐D‐mannosides are better inhibitors of α‐mannosidases than their stereoisomers 6 with the configuration of β‐D‐mannosides. The results show that an aromatic ring (benzyl, [1,1′‐biphenyl]‐4‐yl, 2‐thienyl) is essential for good inhibitory activity. If the C‐chain that separates the aromatic system from the 2‐(aminomethyl) substituent is longer than a methano group, the inhibitory activity decreases significantly (see Fig. 7). This study shows also that α‐mannosidases from jack bean and from almonds do not recognize substrate mimics that are bulky around the O‐glycosidic bond of the corresponding α‐D‐mannopyranosides. These observations should be very useful in the design of better α‐mannosidase inhibitors.
Pre‐Irradiation Grafting of Styrene/Divinylbenzene onto Poly(tetrafluoroethylene‐co‐hexafluoropropylene) from Non‐Solvents
Authors: Rager Timo 
Published: July 2003

AbstractPre‐irradiation grafting of styrene/divinylbenzene (DVB) onto poly(tetrafluoroethylene‐co‐hexafluoropropylene) (FEP) films was studied with respect to the influence of solvent. Particularly favorable grafting conditions with long radical lifetimes and reasonably high polymerization rates were achieved with solvents that are precipitants for the newly formed polystyrene, e.g., low‐molecular‐mass alcohols like iPrOH, AcOH, their mixtures with H2O, and H2O/surfactant systems. Using one of these solvents significantly extended the range of accessible graft levels, and a specific degree of grafting was obtained at a much lower monomer concentration and irradiation dose than with grafting in a good solvent such as toluene. As practical consequences, the monomer was used more efficiently, and the radiation damage of the perfluorinated base material was reduced with the result of improved mechanical properties of the grafted films.
Highly Soluble and Green Indigo Dyes: 4,4′,7,7′‐Tetraalkoxy‐5,5′‐diaminoindigotins
Authors: Voss Gundula , Gradzielski Michael , Heinze Jürgen , Reinke Helmut , Unverzagt Carlo 
Published: July 2003

AbstractTwo new types of 4,4′,7,7′‐tetraalkoxyindigotins, 1a–f and 2a–f along with the new N‐substituted indigotins 4e–f, were synthesized from dinitrobenzaldehydes 5a–f, which were prepared from 2‐hydroxy‐5‐methoxybenzaldehyde (7) via dialkoxybenzaldehydes 6a–f (Scheme). The new dialkoxyindigotin 3g was obtained from dialkoxybenzaldehyde 6g via nitrobenzaldehyde 8g. The 1,4‐dialkoxy‐2,3‐dinitrobenzenes 9 were isolated as by‐products. The 4,4′,7,7′‐tetraalkoxy‐5,5′‐diaminoindigotins 1 are soluble in organic solvents, and their solutions are green, which is highly uncommon for indigotins and is primarily caused by electronic effects of substituents, steric effects playing a minor role. The indigotins 1 produce a strong red shift of the longest‐wavelength absorption and negative solvatochromism indicating the predominance of polar resonance structures in the ground state. Tautomeric structures were excluded. These indigotins are valuable compounds for technical applications, for synthetic purposes, and for analytical studies. SANS (Small‐angle neutron scattering) experiments showed that certain 4,4′,7,7′‐tetraalkoxy‐5,5′‐diaminoindigotins 1 form rod‐like aggregates in solution. The similarly substituted 4,4′,7,7′‐tetraalkoxy‐5,5′‐dinitroindigotins 2 are far less soluble. They produce red monoanions (preferably dimers) and bluish‐purple dianions in organic solvents.
The Effectivity of 1H‐Triazoles and ‐Tetrazoles as Activators in Acid‐Catalyzed Phosphoramidite Alcoholysis
Authors: Nurminen Erkki. J. , Mattinen Jorma K. , Lönnberg Harri 
Published: July 2003

AbstractThe efficiency of 5‐nitro‐1,2,4‐1H‐triazole (3), 5‐(methylthio)‐1H‐tetrazole (4), and 5‐(4‐nitrophenyl)‐1H‐tetrazole (5) as activators in phosphoramidite alcoholysis has been studied relative to 1H‐tetrazole (6). Reactions of these azoles with diisopropyl (diisopropylamido)phosphite (1a) were followed in THF, and the rates were found to increase with increasing acidity of the azoles. The Brønsted α value of 0.7 determined for this dependence is in agreement with data published earlier.
Total Synthesis of the Marine Sesquiterpene Quinones Hyatellaquinone and Spongiaquinone
Authors: Bernet Andreas , Schröder Jörg , Seifert Karlheinz 
Published: July 2003

AbstractThe synthesis of the marine sesquiterpene quinone (+)‐hyatellaquinone (1) was achieved starting from the sesquiterpene aldehyde (+)‐albicanal ((+)‐3) (Schemes 3 and 4). Coupling of (+)‐albicanal with 2,3,5,6‐tetramethoxyphenyllithium led to the aryl‐sesquiterpene system, which was modified to the target molecule. Furthermore, the first total synthesis of the marine compound spongiaquinone (2) was carried out starting from ((−)‐albicanal (−)‐3) in a reaction sequence encompassing a stereoselective CC bond hydrogenation and a one‐pot AcOH elimination/demethylation reaction (Schemes 7 and 10). The occurrence of 1,2‐ and 1,4‐benzoquinone forms of 1 and 2 depends on the pH of the solvent system.
New Glycosides from Salvia moorcroftiana (Lamiaceae)
Authors: Zahid Muhammad , Saeed Muhammad , Asim Muhammad , Ishrud Omar , Wu Shihua , Ahmad Viqar Uddin , Pan Yuanjiang 
Published: July 2003

AbstractFrom the MeOH extract of Salvia moorcroftiana Wall. (Lamiaceae), four new compounds, the two flavonoid glycosides genkwanin 4′‐[O‐α‐L‐rhamnopyranosyl‐(1→2)‐β‐D‐galactopyranoside] (1) and genkwanin 4′‐[O‐α‐L‐arabinopyranosyl‐(1→3)‐α‐L‐rhamnopyranoside] (2), and the two benzene derivatives 4‐hydroxy‐2‐isopropyl‐5‐methylphenyl O‐α‐L‐rhamnopyranosyl‐(1→2)‐β‐D‐glucopyranoside (3) and nonyl 4‐hydroxybenzoate (4), were isolated in addition to two known compounds. The structures of all new compounds were determined by 1D and 2D homonuclear and heteronuclear NMR spectroscopy and by comparison with published data.
Synthesis of the Spermidine Alkaloids (−)‐(2R,3R)‐ and (−)‐(2R,3S)‐3‐Hydroxycelacinnine: Macrocyclization with Oxirane‐Ring Opening and Inversion via Cyclic Sulfamidates
Authors: Khanjin Nikolai A. , Hesse Manfred 
Published: July 2003

AbstractThe two epimers (−)‐1a and (−)‐1b of the macrocyclic lactam alkaloid 3‐hydroxycelacinnine with the (2R,3R) and (2R,3S) absolute configurations, respectively, were synthesized by an alternative route involving macrocyclization with the regio‐ and stereoselective oxirane‐ring opening by the terminal amino group (Schemes 2 and 6). Properly N‐protected chiral trans‐oxirane precursors provided (2R,3R)‐macrocycles after a one‐pot deprotection‐macrocyclization step under moderate dilution (0.005–0.01M). The best yields (65–85%) were achieved with trifluoroacetyl protection. Macrocyclization of the corresponding cis‐oxiranes was unsuccessful for steric reasons. Inversion at OHC(3) via nucleophilic displacement of the cyclic sulfamidate derivative with NaNO2 led to (2R,3S)‐macrocycles. The synthesized (−)‐(2R,3S)‐3‐hydroxycelacinnine ((−)‐1b) was identical to the natural alkaloid.
New Tetracyclic Colchicinoids from the Reaction of N‐Deacetylthiocolchicine and N‐Deacetylcolchicine with Nitrous Acid and tert‐Butyl Nitrite
Authors: Danieli Bruno , Lesma Giordano , Passarella Daniele , Prosperi Davide , Sacchetti Alessandro , Silvani Alessandra , Destro Riccardo , May Emanuela , Bombardelli Ezio 
Published: July 2003

AbstractReaction of N‐deacetylthiocolchicine (3) and N‐deacetylcolchicine (4) with nitrous acid (HONO) furnished the new tetracyclic colchicinoids 5 and 6, as well as the Demyanov‐rearrangement products 7 and 8. Starting from 3, the pyrazole‐containing tetracycle 9 was obtained. The novel compounds were characterized spectroscopically, and an X‐ray crystal‐structure analysis of 5 allowed us to establish the absolute configurations at the stereogenic centers.
Solid‐Phase Synthesis of a β3‐Icosapeptide Containing the Homologs of the Twenty Common Proteinaceous Amino Acids. Preliminary Communication
Authors: Kimmerlin Thierry , Seebach Dieter 
Published: July 2003

AbstractAn icosapeptide, 1, containing the β3‐amino acid residues with the 20 proteinogenic side chains has been assembled by manual solid‐phase synthesis, according to the Fmoc strategy. The sequence was chosen in such a way that a possible 314‐helical conformation (secondary structure) would be stabilized by salt bridges and have an amphipathic character (Fig. 1,a), and the N‐terminal β3hCys would lend itself to thioligations and disulfide formation (2 and 3, in Figs. 1 and 2). The products 1–3 were pure according to RP‐HPLC, NMR, and MS analysis (Fig. 1,b and c, Fig. 2,c and d, and Fig. 3). With due caution, the CD spectra in aqueous solution (pH 7) and in MeOH (Fig. 4), with normalized Cotton effects θ =−14000 to −16000 [deg⋅cm2⋅dmol−1] between 209 and 210 nm, might be taken as an evidence for the presence of 314‐helical conformations. An evaluation of the data from a 700‐MHz 2D‐NMR measurement of the disulfide 2 in CD3OH is in progress.
Three Novel Triterpenoids from the Aerial Part of Helwingia chinensis
Authors: Lai Guo‐Fang , Wang Yi‐Fen , Lu Chun‐Hua , Cao Jian‐Xin , Xu Yun‐Long , Luo Shi‐De 
Published: July 2003

AbstractThree novel triterpenoids named chinenols A–C (1–3), together with two known compounds, glutin‐5‐en‐3β‐ol (4) and daucosterol (5), were isolated from the aerial part of Helwingia chinensis Batal. The structures of 1–3 were determined on the basis of their HR‐EI‐MS, IR, 1H‐ and 13C‐NMR (DEPT), and 2D (HMQC, HMBC, NOESY) data. Compounds 1–3 and 5 showed inhibition activity in an antibacterial assay.
Synthesis and Conformational Switching of Partially and Differentially Bridged Resorcin[4]arenes Bearing Fluorescent Dye Labels. Preliminary Communication
Authors: Azov Vladimir A. , Diederich François , Lill Yoriko , Hecht Bert 
Published: July 2003

AbstractWe report the synthesis of modified Cram‐type cavitands bearing one or two fluorescent labels for single‐molecule spectroscopic studies of vasekite conformational switching (Scheme 3). Syntheses were performed by stepwise bridging of the four couples of neighboring H‐bonded OH groups of resorcin[4]arene bowls (Schemes 2 and 3). The new substitution patterns enable the construction of a large variety of future functional architectures. 1H‐NMR Investigations showed that the new partially and differentially bridged cavitands feature temperature‐ and pH‐triggered vasekite conformational isomerism similar to symmetrical cavitands with four identical quinoxaline bridges (Table). It was discovered that vasekite switching of cavitands is strongly solvent‐dependent.
Two New and a Known Compound from Lawsonia inermis
Authors: Siddiqui Bina S. , Kardar M. Nadeem , Ali S. Tariq , Khan Shazia 
Published: July 2003

AbstractA new obtusafuran derivative, lawsonicin (1), and a new naphthaquinone, lawsonadeem (2), along with a known constituent, vomifoliol (3), were isolated from the aerial parts of Lawsonia alba and characterized by chemical transformation and spectroscopic experiments, including 2D‐NMR techniques.
Development of a New Class of Inhibitors for the Malarial Aspartic Protease Plasmepsin II Based on a Central 7‐Azabicyclo[2.2.1]heptane Scaffold
Authors: Carcache David A. , Hörtner Simone R. , Seiler Paul , Diederich François , Dorn Arnulf , Märki Hans Peter , Binkert Christoph , Bur Daniel 
Published: July 2003

AbstractPlasmepsin II (PMII), a malarial aspartic protease involved in the catabolism of hemoglobin in parasites of the genus Plasmodium, and renin, a human aspartic protease, share 35% sequence identity in their mature chains. Structures of 4‐arylpiperidine inhibitors complexed to human renin were reported by Roche recently. The major conformational changes, compared to a structure of renin, with a peptidomimetic inhibitor were identified and subsequently modeled in a structure of PMII (Fig. 1). This distorted structure of PMII served as active‐site model for a novel class of PMII inhibitors, according to a structure‐based de novo design approach (Fig. 2). These newly designed inhibitors feature a rigid 7‐azabicyclo[2.2.1]heptane scaffold, which, in its protonated form, is assumed to undergo ionic H‐bonding with the two catalytic Asp residues at the active site of PMII. Two substituents depart from the scaffold for occupancy of either the S1/S3 or S2′‐pocket and the hydrophobic flap pocket, newly created by the conformational changes in PMII. The inhibitors synthesized starting from N‐Boc‐protected 7‐azabicyclo[2.2.1]hept‐2‐ene (6; Schemes 1–5) displayed up to single‐digit micromolar activity (IC50 values) toward PMII and good selectivity towards renin. The clear structureactivity relationship (SAR; Table) provides strong validation of the proposed conformational changes in PMII and the occupancy of the resulting hydrophobic flap pocket by our new inhibitors.
A New Class of Inhibitors for the Malarial Aspartic Protease Plasmepsin II Based on a Central 11‐Azatricyclo[6.2.1.02,7]undeca‐2,4,6‐triene Scaffold
Authors: Carcache David A. , Hörtner Simone R. , Bertogg Andreas , Diederich François , Dorn Arnulf , Märki Hans Peter , Binkert Christoph , Bur Daniel 
Published: July 2003

AbstractA new class of nonpeptidic inhibitors of the malarial aspartic protease plasmepsin II (PMII) with up to single‐digit micromolar activities (IC50 values) was developed by structure‐based de novo design. The active‐site matrix used in the design was based on an X‐ray crystal structure of PMII, onto which the major conformational changes seen in the structure of renin upon complexation of 4‐arylpiperidines – including the unlocking of a new hydrophobic (flap) pocket – were modeled. The sequence identity of 35% between mature renin and PMII had prompted us to hypothesize that an induced‐fit adaptation around the active site as observed in renin might also be effective in PMII. The new inhibitors contain a central 11‐azatricyclo[6.2.1.02,7]undeca‐2(7),3,5‐triene core, which, in protonated form, undergoes ionic H‐bonding with the two catalytic Asp residues at the active site of PMII (Figs. 1 and 2). This tricyclic scaffold is readily prepared by a DielsAlder reaction between an activated pyrrole and a benzyne species generated in situ (Scheme 1). Two substituents with naphthyl or 1,3‐benzothiazole moieties are attached to the central core (Schemes 1–4) for accommodation in the hydrophobic flap and S1/S3 (or S2′, depending on the optical antipode of the inhibitor) pockets at the active site of the enzyme. The most‐potent inhibitors (±)‐19a–19c (IC50 3–5 μM) and (±)‐23b (2 μM) (Table) bear an additional Cl‐atom on the 1,3‐benzothiazole moiety to fully fill the rear of the flap pocket. Optimization of the linker between the tricyclic scaffold and the 1,3‐benzothiazole moiety, based on detailed conformational analysis (Figs. 3 and 4), led to a further small increase in inhibitory strength. The new compounds were also tested against other aspartic proteases. They were found to be quite selective against renin, while the selectivity against cathepsin D and E, two other human aspartic proteases, is rather poor (Table). The detailed SARs established in this investigation provide a valuable basis for the design of the next generations of more‐potent and ‐selective PMII inhibitors with potential application in a new antimalarial therapy.