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

Multigram 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.     

Preparation of β2‐Amino Acid Derivatives (β2hThr, β2hTrp, β2hMet, β2hPro, β2hLys,Pyrrolidine‐3‐carboxylic Acid) by Using DIOZ as Chiral Auxiliary

The title compounds were prepared from valine‐derived N‐acylated oxazolidin‐2‐ones, 1 – 3, 7, 9 , by highly diastereoselective (≥ 90%) Mannich reaction (→ 4 – 6 ; Scheme 1) or aldol addition (→ 8 and 10 ; Scheme 2) of the corresponding Ti‐ or B‐enolates as the key step. The superiority of the ‘5,5‐diphenyl‐4‐isopropyl‐1,3‐oxazolidin‐2‐one’ (DIOZ) was demonstrated, once more, in these reactions and in subsequent transformations leading to various t‐Bu‐, Boc‐, Fmoc‐, and Cbz‐protected β²‐homoamino acid derivatives 11 – 23 (Schemes 3–6). The use of ω‐bromo‐acyl‐oxazolidinones 1 – 3 as starting materials turned out to open access to a variety of enantiomerically pure trifunctional and cyclic carboxylic‐acid derivatives.     

Iodo cyclofunctionalization of 2,4‐dialkenyl‐1,3‐dicarbonyl compounds: Synthesis of substituted 3‐(2‐furylidene)‐2‐furanones

A facile method for the synthesis of substituted 3‐(2‐furylidene)‐2‐furanones has been developed using cyclofunctionalization reactions of 2,4‐dialkenyl‐1,3‐dicarbonyl compounds and iodine as electrophile in the presence of Na₂CO₃, in refluxing chloroform. Compounds 4 are obtained in modest to good yields and their structural identification was established by ¹H NMR, ¹H COSY, ¹³C NMR and ¹H‐¹³C COSY. A mechanism has been proposed to rationalize the formation of the ylidene furanone.     

A New Germanium Complex Containing Chelating Pyridinecarboxylate Ligands: cis‐Dihydroxybis(pyridine‐2‐carboxylato‐κN1,κO2)germanium Hydrate (1 : 2) (cis‐[Ge(pyca)2(OH)2]⋅2 H2O)

A new germanium complex, cis‐[Ge(pyca)₂(OH)₂]?2 H₂O ( 1 ; pyca=pyridine‐2‐carboxylato), was synthesized by the reaction of [Ge(acac)₂Cl₂] (acac=acetylacetonato=pentane‐2,4‐dionato) with potassium pyridine‐2‐carboxylate (Kpyca) in H₂O/THF. According to the single‐crystal X‐ray diffraction analysis, each Ge‐atom of 1 is coordinated by two pyca ligands and two OH^? groups (Fig. 1). These molecules are bonded to each other via a system of H‐bonds resulting in a sheet‐like structure (Fig. 2). The complex is decomposed during heating with stepwise mass loss and formation of GeO₂ as final product (Fig. 3).     

Lanthanide(III) Complexes of 2‐[4,7,10‐Tris(phosphonomethyl)‐1,4,7,10‐tetraazacyclododecan‐1‐yl]acetic Acid (H7DOA3P): Multinuclear‐NMR and Kinetic Studies

The protonation constants of 2‐[4,7,10‐tris(phosphonomethyl)‐1,4,7,10‐tetraazacyclododecan‐1‐yl]acetic acid (H₇DOA3P) and of the complexes [Ln(DOA3P)]^4? (Ln=Ce, Pr, Sm, Eu, and Yb) have been determined by multinuclear NMR spectroscopy in the range pD 2–13.8, without control of ionic strength. Seven out of eleven protonation steps were detected (pK =13.66, 12.11, 7.19, 6.15, 5.77, 2.99, and 1.99), and the values found compare well with the ones recently determined by potentiometry for H₇DOA3P, and for other related ligands. The overall basicity of H₇DOA3P is higher than that of H₄DOTA and trans‐H₆DO2A2P but lower than that of H₈DOTP. Based on multinuclear‐NMR spectroscopy, the protonation sequence for H₇DOA3P was also tentatively assigned. Three protonation constants (pK_MHL, pK_MH2L, and pK_MH3L) were determined for the lanthanide complexes, and the values found are relatively high, although lower than the protonation constants of the related ligand (pK , pK , and pK ), indicating that the coordinated phosphonate groups in these complexes are protonated. The acid‐assisted dissociation of [Ln(DOA3P)]^4? (Ln=Ce, Eu), in the region c_H+=0.05–3.00 mol dm^?3 and at different temperatures (25–60°), indicated that they have slightly the same kinetic inertness, being the [Eu(H₂O)₉]³⁺ aqua ion the final product for europium. The rates of complex formation for [Ln(DOA3P)]^4? (Ln=Ce, Eu) were studied by UV/VIS spectroscopy in the pH range 5.6–6.8. The reaction intermediate [Eu(DOA3P)]* as ‘out‐of‐cage’ complex contains four H₂O molecules, while the final product, [Eu(DOA3P)]^4?, does not contain any H₂O molecule, as proved by steady‐state/time‐resolved luminescence spectroscopy.     

Enantioselective Preparation of β2‐Amino Acids with Aspartate,Glutamate, Asparagine,and Glutamine Side Chains

(S)‐β²‐Homoamino acids with the side chains of Asp, Glu, Asn, and Gln have been prepared and suitably protected (N‐Fmoc, CO₂^tBu, CONHTrt) for solid‐phase peptide syntheses. The key steps of the syntheses are: N‐acylation of 5,5‐diphenyl‐4‐isopropyl‐1,3‐oxazolidin‐2‐one (DIOZ) with succinic and glutaric anhydrides (Scheme 2), alkylation of the corresponding Li‐enolates with benzyl iodoacetate and Curtius degradation (Scheme 4), and removal of the chiral auxiliary (Scheme 5). In addition, numerous functional‐group manipulations (CO₂H?CO₂^tBu, CO₂Bn?CO₂H, CbzNH→FmocNH, CO₂H→CO₂NH₂→CONHTrt; Schemes 2, 4, 5, and 6) were necessary, in order to arrive at the four target structures. The configurational assignments were confirmed by X‐ray crystal‐structure determinations (Scheme 2 and Fig. 3). The enantiomeric purities of a β²hAsn and of a β²hGln derivative were determined by HPLC on a Chiralcel column to be 99.7 : 0.3 and >99 : 1, respectively (Fig. 4). Notably, it took up to twelve steps to prepare a suitably protected trifunctional product with a single stereogenic center (overall yield of 10% from DIOZ and succinic anhydride)!     

Preparation of Protected β2‐ and β3‐Homocysteine, β2‐ and β3‐Homohistidine,and β2‐Homoserine for Solid‐Phase Syntheses

The Ser, Cys, and His side chains play decisive roles in the syntheses, structures, and functions of proteins and enzymes. For our structural and biomedical investigations of β‐peptides consisting of amino acids with proteinogenic side chains, we needed to have reliable preparative access to the title compounds. The two β³‐homoamino acid derivatives were obtained by Arndt–Eistert methodology from Boc‐His(Ts)‐OH and Fmoc‐Cys(PMB)‐OH (Schemes 2–4), with the side‐chain functional groups' reactivities requiring special precautions. The β²‐homoamino acids were prepared with the help of the chiral oxazolidinone auxiliary DIOZ by diastereoselective aldol additions of suitable Ti‐enolates to formaldehyde (generated in situ from trioxane) and subsequent functional‐group manipulations. These include OH→O^tBu etherification (for β²hSer; Schemes 5 and 6), OH→STrt replacement (for β²hCys; Scheme 7), and CH₂OH→CH₂N₃→CH₂NH₂ transformations (for β²hHis; Schemes 9–11). Including protection/deprotection/re‐protection reactions, it takes up to ten steps to obtain the enantiomerically pure target compounds from commercial precursors. Unsuccessful approaches, pitfalls, and optimization procedures are also discussed. The final products and the intermediate compounds are fully characterized by retention times (t_R), melting points, optical rotations, HPLC on chiral columns, IR, ¹H‐ and ¹³C‐NMR spectroscopy, mass spectrometry, elemental analyses, and (in some cases) by X‐ray crystal‐structure analysis.     

Stereochemistry of the Methyl Group in (R)‐3‐Methylitaconate Derived by Rearrangement of 2‐Methylideneglutarate Catalysed by a Coenzyme B12‐Dependent Mutase

2‐Methylideneglutarate mutase is an adenosylcobalamin (coenzyme B₁₂)‐dependent enzyme that catalyses the equilibration of 2‐methylideneglutarate with (R)‐3‐methylitaconate. This reaction is believed to occur via protein‐bound free radicals derived from substrate and product. The stereochemistry of the formation of the methyl group of 3‐methylitaconate has been probed using a `chiral methyl group'. The methyl group in 3‐([²H₁,³H]methyl)itaconate derived from either (R)‐ or (S)‐2‐methylidene[3‐²H₁,3‐³H₁]glutarate was a 50 : 50 mixture of (R)‐ and (S)‐forms. It is concluded that the barrier to rotation about the C−C bond between the methylene radical centre and adjacent C‐atom in the product‐related radical [^.CH₂CH(⁻O₂CC=CH₂)CO₂⁻] is relatively low, and that the interaction of the radical with cob(II)alamin is minimal. Hence, cob(II)alamin is a spectator of the molecular rearrangement of the substrate radical to product radical.     

Synthesis and Antimicrobial Evaluation of (1‐(2‐(Benzyloxy)‐2‐oxoethyl)‐1H‐1,2,3‐triazol‐4‐yl)methyl Benzoate Analogues

A convenient one pot synthesis of 20 (1‐(2‐(benzyloxy)‐2‐oxoethyl)‐1H‐1,2,3‐triazol‐4‐yl)methyl benzoate analogues ( 5a – 5t ) with ester functionality was carried out via Cu(I) catalyzed click reaction between prop‐2‐yn‐1‐yl benzoates and benzyl 2‐azidoacetates. The structure of synthesized triazoles were explicated by various spectral techniques like FT‐IR, ¹H NMR, ¹³C NMR, and high‐resolution mass spectrometry and evaluated for in vitro antimicrobial potential against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes, Candida albicans, and Aspergillus niger. Most of synthesized triazole derivatives exhibited average to excellent activity against tested microbial strains.     

A highly efficient synthesis of (Z)‐1‐aryl‐2‐silyl‐1‐ stannylethenes and their conversion to (E)‐2‐ arylethenyl‐, (Z)‐2‐(2‐pyridyl)ethenyl‐ and allenyl‐silanes

A Pd(dba)₂–P(OEt)₃ combination allowed the silastannation of arylacetylenes, 1‐hexyne or propargyl alcohols with tributyl(trimethylsilyl)stannane to take place at room temperature, producing (Z)‐2‐silyl‐1‐stannyl‐1‐substituted ethenes in high yields. Novel silyl(stannyl)ethenes were fully characterized by ¹H‐, ¹³C‐, ²⁹Si‐ and ¹¹⁹Sn‐NMR as well as infrared and mass analyses. Treatment of a series of (Z)‐1‐aryl‐2‐silyl‐1‐stannylethenes and (Z)‐1‐(3‐pyridyl)‐2‐silyl‐1‐stannylethene with hydrochloric acid or hydroiodic acid in the presence of tetraethylammonium chloride (TEACl) or tetrabutylammonium iodide (TBAI) led to the exclusive formation of (E)‐trimethyl(2‐arylethenyl)silanes with high stereoselectivity. A similar reaction of (Z)‐1‐(2‐anisyl)‐2‐silyl‐1‐stannylethene also produced E‐type trimethyl[2‐(2‐anisyl)ethenyl]silane, while (Z)‐trimethyl [2‐(2‐pyridyl)ethenyl]silane was produced exclusively from (Z)‐1‐(2‐pyridyl)‐2‐silyl‐1‐stannylethene. Protodestannylation of (Z)‐1‐[hydroxy(phenyl)methyl]‐2‐silyl‐1‐stannylethene with trifluoroacetic acid took place via the β‐elimination of hydroxystannane, providing trimethyl(3‐phenylpropa‐1,2‐dienyl)silane quite easily. The destannylation products were also fully characterized. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of 3,4‐Dihalogenated Furan‐2‐(5 H)‐ones by Electrophilic Cyclization of 4‐Hydroxy‐2‐alkynoates

Functionalized 3,4‐dihalogenated furan‐2(5 H)‐ones can be readily prepared in moderate to good yields by treating 4‐hydroxy‐4‐arylbut‐2‐ynoate derivatives with ICl, IBr, and I₂. Both halogen atoms of the electrophile are incorporated in the product. The resulting halides can further afford polycyclic aromatic compounds using known palladium‐catalyzed coupling reactions.     

Metallations and Reactions with Electrophiles of 4‐Isopropyl‐5,5‐diphenyloxazolidin‐2‐one (DIOZ) with N‐Allyl and N‐Propargyl Substituents: Chiral Homoenolate Reagents

N‐Allyl, N‐cinnamyl, and N‐(3‐trimethylsilyl)propargyl derivatives of 4‐isopropyl‐5,5‐diphenyloxazolidin‐2‐one (DIOZ) are prepared by lithiation of the parent DIOZ (with BuLi in THF) and reaction with the corresponding bromides (Scheme 1). Lithiation in the same solvent, with deprotonation by BuLi on the allylic or propargylic CH₂ group at dry‐ice temperature, provides colorful solutions, which are either combined with aldehydes or ketones directly or after addition (with or without warming) of (Me₂N)₃TiCl or (i‐PrO)₃TiCl. Conditions have thus been elaborated under which all three types of conjugated lithium compounds react in the γ‐position with respect to the oxazolidinone N‐atom: carbamoyl derivatives of enamines and allenyl amines are formed in yields ranging from 60 to 80% and with diastereoselectivities up to 98% (Schemes 2–5). The C=C bond of the N‐hydroxyalkenyl groups has (Z)‐configuration (products 5 and 8 ), the allene chirality axis has (M)‐configuration (products 9 ), and the addition to aldehydes and unsymmetrical ketones has taken place preferentially from the Si face. A mechanistic model is proposed that is compatible with the stereochemical outcome (assuming kinetic control and disregarding the presence of Li and Ti species in the reaction mixture; cf. L, M in Fig. 4). Hydrolysis of the enamine derivatives leads to lactols, oxidizable to γ‐lactones, with recovery of the crystalline oxazolidinone, as demonstrated in three cases (Scheme 6). Thus, the application of chiral oxazolidinone auxiliaries (cf. Figs. 1 and 2) has been extended to the overall enantioselective preparation of homoaldols.     

Mechanistic Investigation of the Dipolar [2+2] Cycloaddition–Cycloreversion Reaction between 4‐(N,N‐Dimethylamino)phenylacetylene and Arylated 1,1‐Dicyanovinyl Derivatives To Form Intramolecular Charge‐Transfer Chromophores

The kinetics and mechanism of the formal [2+2] cycloaddition–cycloreversion reaction between 4‐(N,N‐dimethylamino)phenylacetylene ( 1 ) and para‐substituted benzylidenemalononitriles 2 b – 2 l to form 2‐donor‐substituted 1,1‐dicyanobuta‐1,3‐dienes 3 b – 3 l via the postulated dicyanocyclobutene intermediates 4 b – 4 l have been studied experimentally by the method of initial rates and computationally at the unrestricted B3LYP/6‐31G(d) level. The transformations were found to follow bimolecular, second‐order kinetics, with ${{\rm{\Delta }}H_{{\rm{exp}}}^{ {\ne} } }$ =13–18 kcal mol^?1, ${{\rm{\Delta }}S_{{\rm{exp}}}^{ {\ne} } }$ ≈?30 cal K^?1 mol^?1, and ${{\rm{\Delta }}G_{{\rm{exp}}}^{ {\ne} } }$ =22–27 kcal mol^?1. These experimental activation parameters for the rate‐determining cycloaddition step are close to the computational values. The rate constants show a good linear free energy relationship (ρ=2.0) with the electronic character of the para‐substituents on the benzylidene moiety in dimethylformamide (DMF), which is indicative of a dipolar mechanism. Analysis of the computed structures and their corresponding solvation energies in acetonitrile suggests that the rate‐determining attack of the nucleophilic, terminal alkyne carbon onto the dicyanovinyl electrophile generates a transient zwitterion intermediate with the negative charge developing as a stabilized malononitrile carbanion. The computational analysis predicted that the cycloreversion of the postulated dicyanocyclobutene intermediate would become rate‐determining for 1,1‐dicyanoethene ( 2 m ) as the electrophile. The dicyanocyclobutene 4 m could indeed be isolated as the key intermediate from the reaction between alkyne 1 and 2 m and characterized by X‐ray analysis. Facile first‐order cycloreversion occurred upon further heating, yielding as the sole product the 1,1‐dicyanobuta‐1,3‐diene 3 m .     

Reactions of 2‐Unsubstituted 1H‐Imidazole 3‐Oxides with 2,2‐Bis(trifluoromethyl)ethene‐1,1‐dicarbonitrile: A Stepwise 1,3‐Dipolar Cycloaddition

The reaction of 1,4,5‐trisubstituted 1H‐imidazole‐3‐oxides 1 with 2,2‐bis(trifluoromethyl)ethene‐1,1‐dicarbonitrile ( 7 , BTF) yielded the corresponding 1,3‐dihydro‐2H‐imidazol‐2‐ones 10 and 2‐(1,3‐dihydro‐2H‐imidazol‐2‐ylidene)malononitriles 11 , respectively, depending on the solvent used. In one example, a 1 : 1 complex, 12 , of the 1H‐imidazole 3‐oxide and hexafluoroacetone hydrate was isolated as a second product. The formation of the products is explained by a stepwise 1,3‐dipolar cycloaddition and subsequent fragmentation. The structures of 11d and 12 were established by X‐ray crystallography.     

Intramolecular Photocyclization of 2‐Acylphenyl Methacrylates: a Convenient Access to 4,5‐Dihydro‐1,4‐epoxy‐2‐benzoxepin‐3(1H)‐ones (= Benzo[c]‐6,8‐dioxabicyclo[3.2.1]octan‐7‐ones

The photochemical reactions of 2‐acylphenyl methacrylates (= 2‐acylphenyl 2‐methylprop‐2‐enoates) 1 were investigated. Irradiation of 2‐acylphenyl methacrylates 1a – d in MeCN gave the tricyclic lactones 2a – d in good yields, together with a small amount of O CO bond cleavage product, the 2‐acylphenols 3a – d (Scheme 2, Table). The formation of the tricyclic lactones 2 probably follows a mechanism involving a 1,7‐diradical through ζ‐H abstraction (1,8‐H transfer) by the excited carbonyl O‐atom (Scheme 3). Irradiation of 2‐acylphenyl tiglate (= 2‐acylphenyl (2E)‐2‐methylbut‐2‐enoate) 1e and 2‐acylphenyl methacrylates 1g – i , substituted by a MeO group (δ‐H) at the 3,5‐positions of the phenyl group, also gave the tricyclic lactones 2e and 2g – i , but in low yields. On the other hand, no H‐abstraction products were observed on irridation of 2‐(ethoxycarbonyl)phenyl methacrylate 1f , of 2‐acylphenyl methacrylate 1j which is substituted by a Me group (γ‐H) at the 3,5‐positions of the phenyl group, and of 1k with an OH group at the 3‐position of the phenyl group.     

Synthesis of 5‐chloro‐2‐methyl‐3‐(5‐methylthiazol‐2‐yl)‐4(3H)‐quinazolinone and related compounds with potential biological activity

Eight new 2‐methyl‐4(3H)‐quinazolinones (8a‐8d, 9c, 9d, 10c, 10d) with one or two chlorine atoms in the benzene ring and a 5‐methyl‐1,3‐thiazol‐2‐yl, 4‐methyl‐1,3‐thiazol‐2‐yl, and 5‐ethyl‐1,3,4‐thiadiazol‐2‐yl substituent in position 3 of the heterocyclic ring were synthesized and characterized. The two step procedure (Scheme 1) utilizes chlorosubstituted anthranilic acids (3a‐3d) and acetic anhydride as the starting materials, with the respective chlorosubstituted 2‐methyl‐4H‐3,1‐benzoxazin‐4‐ones (4a‐4d) as the intermediates. The quinazoline derivatives were characterized by their melting points, elemental analyses and the mass, ultraviolet, infrared, and ¹H and ¹³C nmr spectra. The new compounds are expected to be biologically active.     

Highly Diastereoselective,Biogenetically Patterned Synthesis of (+)‐(1S,6R)‐Volvatellin (=(+)‐(4R,5S)‐5‐Hydroxy‐4‐(5‐methyl‐1‐methylenehex‐4‐en‐2‐ynyl)cyclohex‐1‐ene‐1‐carbaldehyde)

The synthesis of volvatellin ( 4a ), previously isolated from a herbivorous marine mollusk, was achieved with high diastereoselectivity from putative dietary oxytoxin‐1 ( 2 ). A biogenetically patterned carbonyl‐ene route was chosen, proceeding from 2 predominantly via the trans cyclization product 3 without the use of enzymes. This challenges the involvement of enzymes in the formation of 4a in nature. The optical purity and absolute configuration (1S,4S,6R), assigned to 3 from high‐field ¹H‐NMR examination of its Mosher (MTPA) esters 6 , was retained on its chemical conversion to (+)‐(1S,6R)‐configured 4a and is consistent with the (4S) configuration previously established for caulerpenyne ( 1 ).     

A Simple,Convenient, and Efficient Synthetic Route for The Preparation of (Z)‐3,5‐Dichloro‐N‐(3‐(4‐substitutedphenyl)‐4‐phenylthiazole‐2(3H)‐ylide)benzamide Heterocyclic Compounds from Aroyl Thiourea Derivatives via S‐cyclization Mechanism

A series of variously substituted 1,3‐thiazole heterocyclic compounds ( 3a – 3d ) were prepared by base‐catalyzed S‐cyclization of corresponding 2,4‐dichloro‐N‐{[(4‐substitutedphenyl)amino]carbonothioyl}benzamide ( 2a – 2d ) with acetophenone in the presence of bromine. The structure of all compounds was established by IR, ¹H‐NMR, ¹³C‐NMR, elemental analysis, and X‐ray crystallographic analysis.     

1‐(β‐d‐Erythrofuranos­yl)cytidine (β‐erythrocytidine)

1‐(β‐d ‐Erythrofuranosyl)cytidine, C₈H₁₁N₃O₄, (I), a derivative of β‐cytidine, (II), lacks an exocyclic hydroxy­methyl (–CH₂OH) substituent at C4′ and crystallizes in a global conformation different from that observed for (II). In (I), the β‐d ‐erythrofuranosyl ring assumes an E₃ conformation (C3′‐exo; S, i.e. south), and the N‐glycoside bond conformation is syn. In contrast, (II) contains a β‐d ‐ribofuranosyl ring in a ³T₂ conformation (N, i.e. north) and an anti‐N‐glycoside linkage. These crystallographic properties mimic those found in aqueous solution by NMR with respect to furan­ose conformation. Removal of the –CH₂OH group thus affects the global conformation of the aldofuranosyl ring. These results provide further support for S/syn–anti and N/anti correlations in pyrimidine nucleosides. The crystal structure of (I) was determined at 200 K.     

Dimeric Structure of [(η2‐NO3)2(tpy)Bi(μ‐OH)2Bi(tpy)(η2‐NO3)2]

The synthesis and single crystal X‐ray structure determination are reported for the 2,2′ : 6′,2″‐terpyridine (= tpy) adduct of bismuth(III) nitrate. The hydroxide‐bridged dimer [(η²‐NO₃)₂(tpy)Bi(μ‐OH)₂Bi(tpy)(η²‐NO₃)₂] with nine‐coordinate geometry about Bi was the only isolable product from all crystallization attempts in varying ratios of Bi(NO₃) : terpy.; [(η²‐NO₃)₂(tpy)Bi(μ‐OH)₂Bi(tpy) · (η²‐NO₃)₂] is triclinic, P 1, a = 7.941(8), b = 10.732(9), c = 11.235(9) Å; α = 63.05(1), β = 85.01(1), γ = 79.26(1)°, Z = 1, dimer, R = 0.058 for N₀ = 2319.