bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Short Synthesis of the Factor‐Xa Inhibitor DX‐9065a using palladium‐catalyzed key steps
Authors: Kehr Christiane , Neidlein Richard , Engh Richard A. , Brandsretter Hans , Kucznierz Ralf , Leinert Herbert , Marzenell Klaus , Strein Klaus , Saal Wolfgang Von Der 
Published: December 2004

AbstractWe describe a new, efficient synthesis of DX‐9065a (4), a potent inhibitor of the blood coagulation enzyme factor Xa (fXa) which has previously been prepared in more than 20 steps. We saved approximately 10 steps starting with a Pd‐catalyzed cyanation of the triflate 10 of 7‐methoxynaphthalen‐2‐ol (9). After cleavage of the MeO group with boron tribromide, the triflate 6 was coupled to acrylate 5 in a Heck reaction (→3). The subsequent transformations led to DX‐9065 a.
Flash Photolysis of 5‐Methyl‐1,4‐naphthoquinone in Aqueous Solution: Kinetics and mechanism of photoenolization and of enol trapping
Authors: Chiang Yvonne , Kresge A. Jerry , Hellrung Bruno , Schünemann Patrick , Wirz Jakob 
Published: December 2004

Abstract5‐Methyl‐1,4‐naphthoquinone (1) is a remarkable probe to study hydrogen and proton transfer reactions. The photoenol 4‐hydroxy‐5‐methylidene naphthalen‐1 (5H)‐one (2) is formed in the ground state within 2 ps of excitation and with a quantum yield of unity, presumably through a conical intersection of the S0 and S1 hypersurfaces. In aqueous acid, enol 2 is hydrated to 5‐(hydroxymethyl)naphthalene‐1,4‐diol 3 (X  OH, Scheme 1). The rate of hydration of 2 increases linearly with acid concentration from ca. 1.5 × 104 s−1 at pH 6 to reach a maximum value of 9 ×107 s−1 when the remaining carbonyl function is protonated, pKa(2+) = 1.1. Contrary to an earlier suggestion, the rate‐determining step in the acid‐catalyzed hydration of 2 is addition of water to the conjugate acid 2+. Pronounced acceleration of the decay rate of 2 by hydrazoic‐acid buffers indicates competitive trapping of 2+ by the azide ion. In neutral‐to‐weakly‐basic solutions, enol 2 reacts by ionization, pKa(2) = 6.5, and nearly diffusion‐controlled condensation of the carbanionic species 2− with quinone 1. Proto‐nation at the methylidene C‐atom does not compete measurably with protonation on carbonyl O‐atom, despite a Substsial thermodynamic basic for carbon Portoation of ca. 50 kJ mol−1 for 2 and 100 mol−1 for 2−.
Regioselective Enzyme‐Mediated Glycosylation of Natural Polyhydroxy Compounds. Part 1. Galactosylation of stevioside and steviolbioside
Authors: Danieli Bruno , Luisetti Monica , Schubert‐Zsilavecz Manfred , Likussar Werner , Steurer Sabine , Riva Sergio , Monti Daniela , Reiner Josef 
Published: December 2004

AbstractBovine β‐1,4‐galactosyltransierase is an efficient catalyst for the regioselective transfer of galactose from UPD‐galactose, generated in situ with the UDP‐glucose/UDP‐glucose‐4‐epimerase system, to the kaurane glycosides stevioside (1) and Steviolbioside (2), affording the corresponding galactosyl derivatives 3 and 4 in high yields. By a combination of 2D NMR techniques (COSY, TOCSY, ROESY, HMQC, and HMBC), the structure of the products is established as 13‐[(β ‐D‐galactopyranosyl‐(1 → 4)‐β‐D‐glucopyranosyl‐(1 → 2)‐ β ‐D‐glucopyranosyl)oxy]kaur‐16‐en‐19‐oic acid β ‐D‐glucopyranosyl ester (3) and 13‐[(β‐D‐galactopyranosyl‐(1 → 4)‐ β‐D‐glu‐copyranosyl‐(1 → 2)‐ β‐D‐glucopyranosyl)oxy]kaur‐16‐en‐19‐oic acid (4).
Topospecific Reactions of a [5.5.5.5]Fenestradiene with [Fe2(CO)9]
Authors: Wang Jing , Guidetti‐Grept Régine , Keese Reinhart , Stoeckli‐Evans Helen 
Published: December 2004

AbstractN, N‐Dimethylformamide dimethyl acetal transforms an allylic OH group, which is part of a tetracyclic hydrocarbon in a unique elimination reaction into a [5.5.5.5]fenestradiene (2b → 4). In topologically selective reactions of this diene 4 with [Fe2(CO)9,], the [Fe(CO)4(η2‐diene)] and the [Fe(CO)3(η4‐diene)] complexes 8 and 9, respectively, are formed by complexation on one side of the diene moiety, whereas complexation on the other side leads to a [Fe(CO)2(Cp)] complex 10.
Synthesis of Vitamin B12 Derivatives with a Peripheral Metal Binding Site
Authors: Mayor Marcel , Scheffold Rolf , Walder Lorenz 
Published: December 2004

AbstractThe synthesis and structural characterization of the vitamin B12 derivatives 9 and 10 equipped with a peripheral EDTA (ethylenediaminetetraacetic acid) binding site is described. It is based on the condensation of an activated ester of cobester‐c‐acid with ethane‐1,2‐diamine or 2‐aminoethanol followed by acylation of the resulting amines with the monoanhydride 8 of EDTA. The title compounds 9 and 10 can be used as modifiers for metal oxide semiconductor electrodes and are potential precursors for the synthesis of bimetallic, supramolecular catalysts.
Substituent Effects on Fe+‐Mediated [4+2] Cycloadditions in the Gas Phase
Authors: Schroeter Katrin , Schalley Christoph A. , Schröder Detlef , Schwarz Helmut 
Published: December 2004

AbstractThe Fe+‐mediated [4+2] cycloaddition of dienes with alkynes has been examined by four‐sector ion‐beam and ion cyclotron resonance mass spectrometry. Prospects and limitations of this reaction were evaluated by investigating several Me‐substituted ligands. Me Substitution at C(2) and C(3) of the diene, i.e., 2‐methylbuta‐1,3‐diene, 2,3‐dimethylbuta‐1,3‐diene, hardly disturbs the cycloaddition. Similarly, variation of the alkyne by use of propyne and but‐2‐yne does not affect the [4+2] cycloaddition step, but allows for H/D exchange processes prior to cyclization. In contrast, Me substituents in the terminal positions of the diene moiety (e.g., penta‐1,3‐diene, liexa‐2,4‐diene) induce side reactions, namely double‐bond migration followed by [3+2] and [5+2] cycloadditions, up to almost complete suppression of the [4+2] cycloaddition for 2,4‐dimethylhexa‐2,4‐diene. Similarly, alkynes with larger alkyl substituents (pent‐1‐yne, 3,3‐dimethylbut‐1‐yne) suppress the [4 + 2] cycloaddition route. Stereochemical effects have been observed for the (E)‐ and (Z)‐penta‐1,3‐diene ligands as well as for (E,E)‐ and (E,Z)‐hexa‐2,4‐diene. A mechanistic explanation for the different behavior of the stereoisomers in the cyclization reaction is developed. Further, the regiochemical aspects operative in the systems ethoxyacetylene/pentadiene/Fe+ and ethoxyacetylcne/isoprene/Fe+ indicate that substituents avoid proximity.
Photolysis of Steroidal 20‐Aryl‐Substituted 11‐Nitrites
Authors: Kalvoda Jaroslav , Grob Jüren , Bjelakovíć Mira , Lorenc Ljubinka , Mihailovíć Mihailo Lj. 
Published: December 2004

AbstractThe two structurally similar 20‐phenyl‐ and 20‐(4‐methoxyphenyl)‐11‐(nitrosooxy)pregnan‐20‐ol derivatives 4 and 7 behave differently under photolytic conditions, the former nitrous acid ester affording, as a main product, the benzo‐fused hexacyclic compound 9, and the latter the 21‐nitro derivative 12. Mechanistic aspects of these transformations are discussed.
Synthesis of Unnatural Lipohilic N‐(9H‐Fluoren‐9‐ylmethoxy)carbonyl‐Substituted α‐Amino Acids and Their Incorporation into Cyclic RGD‐Peptides: A structure‐activity study
Authors: Koppitz Marcus , Huenges Martin , Gratias Rainer , Kessler Horst , Goodman Simon L. , Jonczyk Alfred 
Published: December 2004

AbstractThe αv/β3 integrin is implicated in human tumor metastasis and angiogenesis. It has been shown that structures of the sequence cyclo(‐Arg1‐Gly2‐Asp3‐D‐Phe4‐Xaa5‐) (I) and cyclo(‐Arg1‐Gly2‐Asp3‐Phe4‐D‐Xaa5‐) (II) bind with high affinity and the latter with high selectivity to this receptor. The residues Xaa and D‐Xaa accept a broad variety of amino acids. Here, we report on the synthesis, activities, and conformational analysis of cyclic Arg‐Gly‐Asp (RGD) peptides containing liophilic amino acids Xaa or D‐Xaa in position 5. For I, these were (2S)‐2‐aminohexadecanoic acid (Ahd) and N′‐hexadecylglycine (Hd‐Gly) and in II, D‐Ahd and Hd‐Gly, and, for control purposes, Ahd were incorporated (Fig. 1). The enantiomerically pure a‐amino acids were obtained by non‐enantioselective synthesis and subsequent enzymatic separation of isomers using acylase I (Scheme). Hd‐Gly was prepared in a modified procedure according to Stewart from ethyl bromoacetate and hexadecylamine (Scheme). The synthesis and physicochemical properties of the corresponding (9H‐fluoren‐9‐ylmethoxy)carbonyl (Fmoc) derivatives, compatible with solid‐phase peptide synthesis, are described. Structure elucidation by NMR reveals that the lipid modification has no significant impact on the template structures when incorporated into them. For peptides I with Xaa = Ahd or Hd‐Gly (1 or 2), a βII′/γ‐turn‐like arrangement with D‐Phe in i+1 position of the β‐turn is found. Peptides II with D‐Xaa = D‐Ahd or Hd‐Gly (3 or 4) exhibit a βII′/γ‐turn conformation with Gly in i+1 position of the β‐turn, whereas II with Ahd instead of D‐Xaa, i.e., lacking a D‐amino acid in position 4 or 5 (5). adopts no defined conformation. However, in assays of receptor specificity employing human αvv/β3 integrin, the compounds exhibit IC50 values ranging from nanomolar to less than millimolar. These results indicate that although the arrangement of the pharmacophoric groups is preserved in the target compounds, the biological activity is highly dependent on spatial requirements of the lipid anchor in the receptor binding pocket. Obviously, only certain positions do not affect the binding.
Studies on the Base‐Pairing Properties of N7‐(2‐Deoxy‐β‐D‐erythro‐pentofuranosyl)guanine (N7Gd)
Authors: Seela Frank , Leonard Peter 
Published: December 2004

AbstractThe base‐pairing properties of N7‐(2‐deoxy‐β‐D‐erythro‐pentofuranosyl)guanine (N7Gd; 1) are investigated. The nucleoside 1 was obtained by nucleobase‐anion glycosylation. The glycosylation reaction of various 6‐alkoxy‐purin‐2‐amines 3a‐i with 2‐deoxy‐3,5‐di‐O‐(4‐toluoyl)‐α‐D‐erythro‐pentofuranosyl chloride (8) was studied. The N9/N7‐glycosylation ratio was found to be 1:1 when 6‐isopropoxypurin‐2‐amine (3d) was used, whereas 6‐(2‐methoxyethoxy)purin‐2‐arnine (3i) gave mainly the N9‐nucleoside (2:1). Oligonucleotides containing compound 1 were prepared by solid‐phase synthesis and hybridized with complementary strands having the four conventional nucleosides located opposite to N7Gd. According to Tm values and enthalpy data of duplex formation, a base pair between N7Gd and dG is suggested. From the possible N7Gd dG base pair motives, Hoogsteen pairing can be excluded as 7‐deaza‐2′‐deoxyguanosine forms the same stable base pair with N7Gd as dG.
Synthesis and Properties of 2′‐Deoxy‐1′,2′‐seco‐D‐ribosyl (5′ → 3′)oligonucleotides (= 1′,2′‐seco‐DNA) containing adenine and thymine
Authors: Peng Ling , Roth Hans‐Jorg 
Published: December 2004

AbstractSome 2′‐deoxy‐1′,2′‐seco‐D‐ribosyl (5′→3′)oligonucleotides (= 1′,2′‐seco‐DNA), differing from natural DNA only by a bond scission between the centers C(1′) and C(2′), were synthesized and studied in order to compare their structure properties and pairing behavior with those of corresponding natural DNA and homo‐DNA oligonucleotides (2′,3′‐dideoxy‐β‐D‐glucopyranosyl oligonucleotides). Starting from (−)‐D‐tartaric acid, 2′‐deoxy‐1′,2′‐secoadenosine derivative 9a and 1′,2′‐secothymidine (9b) were obtained in pure crystalline form. Using the phosphoramidite variant of the phosphite‐triester method, a dinucleotide monophosphate 1′,2′‐seco‐d(T2) was synthesized in solution, while oligonucleotides 1′,2′‐seco‐d[(AT)6], 1′,2′‐seco‐d(A10) and 1′,2′‐seco‐d(T10) were prepared on solid phase with either automated or manual techniques. Results of UV‐ and CD‐spectroscopic as well as gel‐electrophoretic studies indicated that neither adenine‐thymine base pairing (as observed in natural DNA and homo‐DNA), nor the adenine‐adenine base pairing (as observed in homo‐DNA) was effective in 1′,2′‐seco‐DNA, Furthermore, hybrid pairing was observed neither between 1′.2′‐seco‐DNA and natural DNA nor between 1′,2′‐seco‐DNA and homo‐DNA.
Catalytic Cyclophanes. Part XI. A flavo‐thiazolio‐cyclophane as a biomimetic catalyst for the preparative‐scale electro‐oxidation of aromatic aldehydes to methyl esters
Authors: Mattei Patrizio , Diederich François 
Published: December 2004

AbstractFlavo‐thiazolio‐cyclophane 6 was prepared on a gram scale by an 18‐step synthesis (Schemes 3 and 4). This pathway involved the very efficient preparation of bromo‐cyclophane 32 (37% yield over 13‐steps), which can be readily modified to create various multiply functionalized receptors. This bromide 32 was subsequently converted into the corresponding boronic acid and connected to the 7‐bromoflavin 10 (Scheme 2) via Suzuki coupling to give flavo‐cyclophane 36. The thiazolium unit was then introduced after quaternization of the tertiary amino groups of 36. Flavo‐thiazolio‐cyclophane 6, with both prosthetic groups attached in proximity to the well‐defined cyclophane binding site, is a functional model for the enzyme pyruvate oxidase. In basic methanolic solution, 6 catalyzes the oxidation of aromatic aldehydes to their corresponding methyl esters. Cyclophane 6 shows saturation kinetics, and the turnover number calculated for the oxidation of naphthalene‐2‐carbaldehyde to methyl naphthalene‐2‐carboxylate (kcat = 0.22 s−1) is one of the highest reported for an artificial enzyme. Control experiments showed that the catalytic advantages of 6 result from the macrocyclic binding and reaction site as well as from the covalent attachment of both cofactors to this site. The catalytic cycle is completed by electrochemical re‐oxidation of the reduced flavin moiety at a low working electrode potential (‐ 0.3 V vs. Ag/AgCl), and up to ca. 100 catalytic cycles can be performed on a preparative scale, The intramolecular nature of the electron transfer from the active aldehyde intermediate to the flavin is particularly conducive to the oxidation of unreactive aldehydes.
Synthesis and Odor of Chiral Partial Structures of Khusimone. Part 2
Authors: Spreitzer Helmut , Pichler Andrea , Holzer Wolfgang , Shahabi Manocher 
Published: December 2004

AbstractKhusimone (1), one of the main odor‐donating compounds of vetiver oil, is subject of the following study on structure/odor relationship. Ring opening of the carbonyl‐functionalized bridge of the tricyclic khusimone leads to the bicyclic structures 2a/b. The enantioselective approach to these degraded structures is described, and the olfactory consequences are studied. Starting point of the synthesis is an enantiomerically pure enone ester which is easily obtainable from camphorsulfonic acid.
Enantioselective Synthesis of Planar Chiral [Cr(η6‐Arene)(CO)3] complexes via nucleophilic addition/hydride abstraction. Preliminary communication
Authors: Fretzen Angelika , Kündig E. Peter 
Published: December 2004

AbstractNon‐racemic, planar chiral 1, 2‐disubstituted [Cr(η6‐arene)(CO)3] complexes were obtained via external chiral ligand‐controlled nucleophilic addition of alkyl‐, vinyl‐, and aryllithium reagents to monosubstituted complexes followed by an endo‐hydride abstraction with trityl cation. The reactions with [Cr(CO)3(η6‐phenyloxazoline)], [Cr(CO)3(η6‐phenylmethaneimine)], and [Cr(CO)3 (η6‐phenylmethanenydrazone)] took place with complete ortho‐selectivity and a high degree of enantioselectivity (up to 98% ee).
TADDOLs under closer scrutiny – why bulky substituents make it all different
Authors: Beck Albert K. , Dobler Max , Plattner Dietmar A. 
Published: December 2004

AbstractA systematic investigation of the rotational behavior of aryl substituents in α,α,α′,α′‐tetraaryl‐1,3‐dioxolane‐4,5‐dimethanols (TADDOLs) is presented. In the use as chiral ligands for enantioselective metal‐catalyzed reactions, a change from phenyl to bulkier substituents, e.g., 1‐naphthyl, gives rise to an astounding alteration of the selectivity, The possible existence of preferred rotamers of TADDOLs has so far not been given due attention, which encouraged us to look at the validity of the Knowles model, originally formulated for diaryl substituted bisphosphines. 1H‐NMR Investigations at various temperatures as well as X‐ray powder diffraction were employed to study the rotation in the case of tetra(1‐naphthyl) TADDOL 1. To support the interpretation of the experimental results, molecular mechanics, semiempirical, and ab initio calculations were performed. For comparison, the energy surface of tetraphenyl TADDOL 2 was calculated as well. Our results lead to the conclusion that for 1, only one major conformation is present in both solution and solid state, which determines the stereochemical outcome of the catalyzed reactions.
Properties and reactivity in groups of the periodic system: Ion‐molecule reactions CH3X + CH3X+· (X = F through At)
Authors: Zahradník Rudolf , Šroubková Libuše 
Published: December 2004

AbstractThe reactions indicated in the title have been studied in terms of direct processes and complex formation. Quantum‐chemical methods have been applied to the passage of an acid (H+, CH, X+) from CH3X+· to CH3X, and the abstraction of a radical (H· CH, X·) from CH3X by CH3X+·. It has been shown that a complex represented by a dimer of a methyl‐halide radical cation, (CH3X), with a two‐center three‐electron bond XX, has fairly high stability. These investigations were based on non‐empirical quantum‐chemical calculations, the results being systematically compared with experimental determinations. Some calculations included all electrons (X=F, Cl, Br), others were based on relativistic pseudopotentials (X=F through At). The two sets of calculations agree qualitatively with each other and with experimental observations.
Comparative study of the cope rearrangement of hexa‐1,5‐diene and barbaralane
Authors: Baumann Harold , Voellinger‐Borel Aline 
Published: December 2004

AbstractThe classical rules for Cope rearrangements predict a transition state with chair form to be favored over the boat form. On the other hand, bridged homotropylidenes, which allow only a boat‐form transition state by steric reasons, have extremely low barriers. A controversy about the correct pathway and the different possible intermediates and transition states of the reaction has gone on for years. In this work, the hypersurfaces of barbaralane, in comparison with the boat‐ and chair‐form of hexa‐1,5‐diene, are computed by the ab inito CASSCF (6,6)/6‐31G** method starting with UMP2/6‐31G** natural orbitals (NO's). All three hypersurfaces show characteristic features, and, moreover differ from each other. A hitherto undiscussed intermediate, bicyclo[2.2.0]hexane, was localized on the boat‐hexa‐1,5‐diene pathway. So it is noteworthy that our transition state for the boat‐hexa‐1,5‐diene does not correspond to the transition states found by other authors for this conformation. The computed enthalpies of activation of boat‐ and chair‐hexa‐1,5‐diene, and barbaralane are in good agreement with the experimental data.
Nucleic Acid Analogs with Constraint Conformational Flexibility in the Sugar‐Phosphate Backbone “Tricyclo‐DNA”. Part 1. Preparation of [(5′R,6′R)‐2′‐deoxy‐3′,5′‐ethano‐5′,6′‐methano‐β‐D‐ribofuranosyl]thymine and ‐adenine, and the corresponding phosphoramidites for oligonucleotide synthesis
Authors: Steffans Ralph , Leumann Christian 
Published: December 2004

AbstractThe synthesis of the tricyclo‐deoxynucleoside analogs 1 and 2 and of the corresponding cyanoethyl phosphoramidite building blocks 16 and 21 for oligonucleotide synthesis is described. These tricyclic deoxynucleoside analogs differ from the recently introduced bicyclo‐deoxynucleosides by an additional cyclopropane unit joined to the centers C(5′) and C(6′) of the latter (se Fig. 1), and thus represent a further member of the class of nucleoside analogs with constraint conformational flexibility. The synthesis of the tricyclo‐deoxynucleoside was achieved by a diastereoselective carbene addition to the enantiomerically pure silyl enol either 8/9 and a Vorbrüggen condensation of the tricyclic carbohydrate unit 10/11 with in situ persilylated thymine and N6‐benzoyladenine. Selective tritylation of the tertiary OHC(5′) and phosphinylation of OHC(3′) of 1 and 2 afforded the corresponding phosphoramidites 16 and 21. The ‘exo’‐configuration of the newly introduced cyclopropane ring was confirmed by 1H‐NMR‐NOE spectroscoy. The α‐D‐ and β‐D‐configuration at C(1′) of the nucleoside analogs 1 and 14 (2 and 19, resp.) was assigned by 1H‐NMR‐NOE spectroscopy and NOESY. Modeling studies of the β‐D‐anomeric nucleoside analog 1 indicate a preference for the 2′‐endo‐conformation of the furanose ring and a partial correction of the torsion angle γ to the anti‐clinal range compared to bicyclo‐deoxynucleosides.
Four Novel Glycosides from the Aphid Pseudoregma bambmicola T
Authors: Zhang Guo‐lin , He Mei‐yu , Xing Qi‐yi 
Published: December 2004

AbstractFour novel glycosides, bambusicolasides III–VI (1–4), were isolated from the aphid Pseudoregma bambusicola T. The structures of 1–4 were elucidated by spectral evidence including FAB‐MS and C.H‐COSY, HMBC, and NOE difference experiments, and by hydrolysis. In vitro tests with these compounds showed little cytotoxic activity against human KB cells (< 10%).
TADDOLs with Unprecedented Helical Twisting Power in Liquid Crystals. Preliminary communication
Authors: Kuball Hans‐Georg , Weiß Bernhard , Beck Albert K. , Seebach Dieter 
Published: December 2004

AbstractA large number of TADDOL (α,α,α′, α′‐tetraaryl‐1,3‐dioxolan‐4,5‐dimethanol) derivatives has been tested as chiral dopants for inducing conversion of nematic to cholesteric phases. With the Merck liquid‐crystal materials ZLI‐1695 and K15, it was demonstrated that some TADDOLs have unprecedentedly high helical twisting powers (HTP). Thus, the TADDOL with four 9‐phenanthryl α‐substituents has a HTP in the achiral mesophase 4‐(4‐pentylphenyl)benzonitrile of 405 μm−1 between 24 and 34°. The temperature‐dependent HTP measurements have been performed by analyzing Grandjean textures microscopically (Cano method). The structure‐dependent HTP of various types of TADDOL dopants is discussed. There are similarities between size and sign of HTP on the one hand, and between degree and relative topicity of enantioselectivity in reactions, on the other hand, as caused by TADDOLs and by 1,1′‐binaphthols.
[2+3] Cycloadditions of ‘Thiocarbonyl Ylides’ (= (Alkylidenesulfonio)methanides) and diazoalkanes with N,N′‐(thiocarbonyl)diimidazole (= 1,1′‐(carbonothioyl)bis[1H‐imidazole])
Authors: Mlostoń Grzegorz , Gendek Tomasz , Linden Anthony , Heimgartner Heinz 
Published: December 2004

AbstractHeating of a mixture of N,N′‐(thiocarbonyl)diimidazole (= 1,1′‐(carbonothioyl)bis[1H‐imidazole]; 1) and 2,5‐dihydro‐1,3,4‐thiadiazole 2a or 2b gave the 1,3‐dithiolanes 4a and 4b, respectively, via a regiospecific 1,3‐dipolar cycloaddition of the corresponding ‘thiocarbonyl methanides’ 3a,b onto the CS group of 1 (Schemes 1 and 2). The adamantane derivative 4b was not stable in the presence of 1H‐imidazole and during chromatographic workup. The isolated 1,3‐dithiole 5 is the product of a base‐catalyzed elimination of 1H‐imidazole from the initial cycloadduct 4b. The formation of the S,N‐acetal 6 can be rationalized by a protonation of the ‘thiocarbonyl ylide’ 3b followed by a nucleophilic addition of 1H‐imidazole. With the diazo compounds 8a–e (Scheme 3) 1 underwent a regiospecific 1,3‐dipolar cycloaddition to give the corresponding 2,5‐dihydro‐1,3,4‐thiadiazole derivatives 9, which spontaneously eliminated 1H‐imidazole to yield (1H‐imidazol‐1‐yl)‐1,3,4‐thiadiazoles 10. The structures of 10a and 10d were established by X‐ray crystallography. In the case of diazodiphenylmethane (8f), the initial cycloadduct 9f decomposed via a ‘twofold extrusion’ of N2 and S to give 1,1′‐(2,2‐diphenylethenylidene)bis[1H‐imidazole] (11; Scheme 3).