Development of Potential Therapeutic Agents from Black Elderberries (the Fruits of Sambucus nigra L.).

Elderberry (Sambucus nigra L.) is a widespread deciduous shrub, of which the fruits (elderberries) are used in the food industry to produce different types of dietary supplement products. These berries have been found to show multiple bioactivities, including antidiabetic, anti-infective, antineoplastic, anti-obesity, and antioxidant activities. An elderberry extract product, Sambucol®, has also been used clinically for the treatment of viral respiratory infections. As the major components, phenolic compounds, such as simple phenolic acids, anthocyanins and other flavonoids, and tannins, show promising pharmacological effects that could account for the bioactivities observed for elderberries. Based on these components, salicylic acid and its acetate derivative, aspirin, have long been used for the treatment of different disorders. Dapagliflozin, an FDA-approved antidiabetic drug, has been developed based on the conclusions obtained from a structure-activity relationship study for a simple hydrolyzable tannin, ß-pentagalloylglucoside (ß-PGG). Thus, the present review focuses on the development of therapeutic agents from elderberries and their small-molecule secondary metabolites. It is hoped that this contribution will support future investigations on elderberries.

Vincamine, from an antioxidant and a cerebral vasodilator to its anticancer potential.

Vincamine is a naturally occurring indole alkaloid showing antioxidant activity and has been used clinically for the prevention and treatment of cerebrovascular disorders and insufficiencies. It has been well documented that antioxidants may contribute to cancer treatment, and thus, vincamine has been investigated recently for its potential antitumor activity. Vincamine was found to show cancer cell cytotoxicity and to modulate several important proteins involved in tumor growth, including acetylcholinesterase (AChE), mitogen-activated protein kinase (MAPK), nuclear factor-κB (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), and T-box 3 (TBX3). Several bisindole alkaloids, including vinblastine and vincristine and their synthetic derivatives, vindesine, vinflunine, and vinorelbine, have been used as clinically effective cancer chemotherapeutic agents. In the present review, the discovery and development of vincamine as a useful therapeutic agent and its antioxidant and antitumor activity are summarized, with its antioxidant-related mechanisms of anticancer potential being described. Also, discussed herein are the design of the potential vincamine-based oncolytic agents, which could contribute to the discovery of further new agents for cancer treatment.

Panchromatic dirhodium photocatalysts for dihydrogen generation with red light.

A series of three dirhodium complexes cis-[Rh2(DPhB)2(bncn)2](BF4)2 (1, DPhB = diphenylbenzamidine; bncn = benzocinnoline), cis-[Rh2(DPhTA)2(bncn)2](BF4)2 (2, DPhTA = diphenyltriazenide), and cis-[Rh2(DPhF)2(bncn)2](BF4)2 (3, DPhF = N,N'-diphenylformamidinate) shown to act as single-molecule photocatalysts for H2 production was evaluated. Complexes 1-3 are able to generate H2 in the absence of any other catalyst in homogenous acidic solution upon irradiation with red light in the presence of the sacrificial electron donor BNAH (1-benzyl-1,4-dihydronicotinamide). The excited state of each complex is reductively quenched by BNAH, producing the corresponding one-electron reduced complex. The latter is also able to absorb a photon and oxidize another BNAH molecule, producing the doubly-reduced, activated form of the catalyst that is able to generate H2. The present work shows the effect of substitution on the bridging ligands on the driving force for reductive quenching and hydricity of the proposed active intermediate, both of which affect the efficiency of hydrogen production. Complexes 1-3 operate following a double reductive quenching mechanism and, importantly, are active with red light. This work lays the foundation for the design of single-molecule photocatalysts that operate from the ultraviolet to the near-infrared, such that solar photons throughout this entire range are harnessed and utilized for solar energy conversion.

α-Pyrone and Sterol Constituents of Penicillium aurantiacobrunneum, a Fungal Associate of the Lichen Niebla homalea.

Four new metabolites, 4-epi-citreoviridin (1), auransterol (3), and two analogues (2 and 4) of paxisterol (6), together with two known metabolites (15R*,20S*)-dihydroxyepisterol (5) and (6), were isolated from cultures of the fungal associate, Penicillium aurantiacobrunneum, of the lichen Niebla homalea, endemic to California and Baja California. The structures of all compounds were determined by comprehensive spectroscopic and spectrometric methods, as well as single-crystal X-ray diffraction for the determination of the absolute configuration of 3. Compound 1 showed selective cytotoxicity toward MCF-7 breast and A2780 ovarian cells with IC50 values of 4.2 and 5.7 µM, respectively.

Cationic Co(I)-Intermediates for Hydrofunctionalization Reactions: Regio- and Enantioselective Cobalt-Catalyzed 1,2-Hydroboration of 1,3-Dienes.

Much of the recent work on catalytic hydroboration of alkenes has focused on simple alkenes and styrene derivatives with few examples of reactions of 1,3-dienes, which have been reported to undergo mostly 1,4-additions to give allylic boronates. We find that reduced cobalt catalysts generated from 1,n- bis-diphenylphosphinoalkane complexes [Ph2P-(CH2) n-PPh2]CoX2; n = 1-5) or from (2-oxazolinyl)phenyldiarylphosphine complexes [(G-PHOX)CoX2] (G = 4-substituent on oxazoline ring) effect selective 1,2-, 1,4-, or 4,3-additions of pinacolborane (HBPin) to a variety of 1,3-dienes depending on the ligands chosen. Conditions have been found to optimize the 1,2-additions. The reactive catalysts can be generated from the cobalt(II)-complexes using trimethylaluminum, methyl aluminoxane, or activated zinc in the presence of sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate (NaBARF). The complex, (dppp)CoCl2, gives the best results (ratio of 1,2- to 1,4-addition >95:5) for a variety of linear terminal 1,3-dienes and 2-substituted 1,3-dienes. The [(PHOX)CoX2] (X = Cl, Br) complexes give mostly 1,4-addition with linear unsubstituted 1,3-dienes, but, surprisingly, selective 1,2-additions with 2-substituted or 2,3-disubstituted 1,3-dienes. Isolated and fully characterized (X-ray crystallography) Co(I)-complexes, (dppp)3Co2Cl2 and [( S,S)-BDPP]3Co2Cl2, do not catalyze the reaction unless activated by a Lewis acid or NaBARF, suggesting a key role for a cationic Co(I) species in the catalytic cycle. Regio- and enantioselective 1,2-hydroborations of 2-substituted 1,3-dienes are best accomplished using a catalyst prepared via activation of a chiral phosphinooxazoline-cobalt(II) complex with zinc and NaBARF. A number of common functional groups, among them, -OBn, -OTBS, -OTs, N-phthalimido- groups, are tolerated, and er's > 95:5 are obtained for several dienes including 1-alkenylcycloalk-1-enes. This operationally simple reaction expands the realm of asymmetric hydroboration to provide direct access to a number of nearly enantiopure homoallylic boronates, which are not readily accessible by current methods. The resulting boronates have been converted into the corresponding alcohols, potassium trifluororoborate salts, N-BOC amines, and aryl derivatives by C-BPin to C-aryl transformation.

Crystal Structures and Human Leukemia Cell Apoptosis Inducible Activities of Parthenolide Analogues Isolated from Piptocoma rufescens.

The molecular structures of three parthenolide analogues, (-)-goyazensolide (1), (-)-15-deoxygoyazensolide (2), and (-)-ereglomerulide (3), isolated from the leaves of Piptocoma rufescens in a previous study were determined by X-ray analysis, and the absolute configuration of (-)-goyazensolide (1) was confirmed crystallographically using Cu Kα radiation at low temperature. Compounds 1-3, (+)-rufesolide A (4), and commercial parthenolide were found to be growth inhibitory toward MOLM-13 and EOL-1 human acute myeloid leukemia cells using PKC412 (midostaurin) as the positive control, with 1-3 being more active than parthenolide. Also, compounds 1-4 exhibited synergistic effects when tested with PKC412, but parthenolide did not show this type of activity. At a concentration lower than 2.0 µM, both 1 and 2 induced approximately 50% of the cells to become apoptotic at a late stage of the cell cycle, but no similar apoptotic effects were observed for 3, 4, or parthenolide. Leukemia cell apoptosis was induced by these compounds through the activation of caspase-3 and the inhibition of NF-κB, as indicated by immunoblotting analysis, and compounds 1 and 2 seem to be promising leads for development as potential antileukemic agents.

Catalytic Enantioselective Hetero-dimerization of Acrylates and 1,3-Dienes.

1,3-Dienes are ubiquitous and easily synthesized starting materials for organic synthesis, and alkyl acrylates are among the most abundant and cheapest feedstock carbon sources. A practical, highly enantioselective union of these two readily available precursors giving valuable, enantio-pure skipped 1,4-diene esters (with two configurationally defined double bonds) is reported. The process uses commercially available cobalt salts and chiral ligands. As illustrated by the use of 20 different substrates, including 17 prochiral 1,3-dienes and 3 acrylates, this hetero-dimerization reaction is tolerant of a number of common organic functional groups (e.g., aromatic substituents, halides, isolated mono- and di-substituted double bonds, esters, silyl ethers, and silyl enol ethers). The novel results including ligand, counterion, and solvent effects uncovered during the course of these investigations show a unique role of a possible cationic Co(I) intermediate in these reactions. The rational evolution of a mechanism-based strategy that led to the eventual successful outcome and the attendant support studies may have further implications for the expanding use of low-valent group 9 metal complexes in organic synthesis.

New Rh2(II,II) Complexes for Solar Energy Applications: Panchromatic Absorption and Excited-State Reactivity.

The new heteroleptic paddlewheel complexes cis-[Rh2(µ-form)2(µ-np)2][BF4]2, where form = p-ditolylformamidinate (DTolF) or p-difluorobenzylformamidinate (F-form) and np = 1,8-napthyridyine, and cis-Rh2(µ-form)2(µ-npCOO)2 (npCOO- = 1,8-naphthyridine-2-carboxylate), were synthesized and characterized. The complexes absorb strongly throughout the ultraviolet (λmax = 300 nm, ε = 20 300 M-1 cm-1) and visible regions (λmax = 640 nm ε = 3500 M-1 cm-1), making them potentially useful new dyes with panchromatic light absorption for solar energy conversion applications. Ultrafast and nanosecond transient absorption and time-resolved infrared spectroscopies were used to characterize the identity and dynamics of the excited states, where singlet and triplet Rh2/form-to-naphthyridine, metal/ligand-to-ligand charge-transfer (ML-LCT) excited states were observed in all four complexes. The npCOO- complexes exhibit red-shifted absorption profiles extending into the near-IR and undergo photoinitiated electron transfer to generate reduced methyl viologen, a species that persists in the presence of a sacrificial donor. The energy of the triplet excited state of each complex was estimated from energy-transfer quenching experiments using a series of organic triplet donors (E(3ππ*) from 1.83 to 0.78 eV). The singlet reduction (+0.6 V vs Ag/AgCl) potentials, and singlet and triplet oxidation potentials (-1.1 and -0.5 V vs Ag/AgCl, respectively) were determined. Based on the excited-state lifetimes and redox properties, these complexes represent a new class of light absorbers with potential application as dyes for charge injection into semiconductor solar cells and in sensitizer-catalyst assemblies for photocatalysis that operate with irradiation from the ultraviolet to ∼800 nm.

Probing Interligand Electron Transfer in the 1MLCT S1 Excited State of trans-Mo2L2L'2 Compounds: A Comparative Study of Auxiliary Ligands and Solvents.

The interligand charge dynamics of the lowest singlet metal-to-ligand charge-transfer states (1MLCT S1 states) of a series of quadruply bonded trans-Mo2(NN)2(O2C-X)2 paddlewheel compounds are investigated, where NN is a π-accepting phenylpropiolamidinate ligand and O2C-X (X = Me, tBu, TiPB, or CF3) is an auxiliary carboxylate ligand. The compounds show strong light absorption in the visible region due to MLCT transitions from the Mo2 center to the NN ligands. The transferred electron density was followed by femtosecond time-resolved infrared (fs-TRIR) spectroscopy with vibrational reporters such as the ethynyl groups on the NN ligands. The observed fs-TRIR spectra show that these compounds have asymmetric 1MLCT S1 excited states where the transferred electron mainly resides on a single NN ligand. The presence of interligand electron transfer (ILET) is suggested to explain the shape of the ν(C≡C) bands and the influence of auxiliary ligands and solvents on the interligand electronic coupling. The ILET in the 1MLCT S1 state is shown to be sensitive to the functional groups on the auxiliary ligands while being less responsive to changes in solvents.

An Intramolecular CAr-H•••O=C Hydrogen Bond and the Configuration of Rotenoids.

Over the past half a century, the structure and configuration of the rotenoids, a group of natural products showing multiple promising bioactivities, have been established by interpretation of their NMR and electronic circular dichroism spectra and confirmed by analysis of single-crystal X-ray diffraction data. The chemical shift of the H-6' 1H NMR resonance has been found to be an indicator of either a cis or trans C/D ring system. In the present study, four structures representing the central rings of a cis-, a trans-, a dehydro-, and an oxadehydro-rotenoid have been plotted using the Mercury program based on X-ray crystal structures reported previously, with the conformations of the C/D ring system, the local bond lengths or interatomic distances, hydrogen bond angles, and the H-6' chemical shift of these compounds presented. It is shown for the first time that a trans-fused C/D ring system of rotenoids is preferred for the formation of a potential intramolecular C6'-H6'•••O=C4 H-bond, and that such H-bonding results in the 1H NMR resonance for H-6' being shifted downfield.

Femtosecond Study of Dimolybdenum Paddlewheel Compounds with Amide/Thioamide Ligands: Symmetry, Electronic Structure, and Charge Distribution in the 1MLCT S1 State.

Four photophysically interesting dimolybdenum paddlewheel compounds are synthesized and characterized: I and II contain amide ligand (N,3-diphenyl-2-propynamide), and III and IV contain thioamide ligand (N,3-diphenyl-2-propynethioamide). I and III are trans-Mo2L2(O2C-TiPB)2-type compounds, and II and IV are Mo2L4-type compounds, where O2C-TiPB is 2,4,6-triisopropylbenzoate. I-IV display strong light absorption due to metal to ligand charge transfer (MLCT) transitions from molybdenum to the amide/thioamide ligands. Charge transfer dynamics in the MLCT excited states of I-IV have been examined using femtosecond transient absorption (fs-TA) spectroscopy and femtosecond time-resolved infrared (fs-TRIR) spectroscopy. The asymmetric amide/thioamide ligands show two forms of regioarrangements in the paddlewheel compounds. Analyses of the ν(C≡C) bands in the fs-TRIR spectra of I and II show similar electron density distribution over ligands in their 1MLCT S1 states where only two amide ligands are involved and the transferred electron is mainly localized on one of them. The fs-TRIR spectra of III and IV, however, show different charge distribution patterns where the transferred electron is fully delocalized over two thioamide ligands in III and partially delocalized in IV. Fast interligand electron transfer (ILET) was recognized as the explanation for the various charge distribution patterns, and ILET was shown to be influenced by both the ligands and the ligand arrangements.

Potent cytotoxic arylnaphthalene lignan lactones from Phyllanthus poilanei.

Two new (1 and 2) and four known arylnaphthalene lignan lactones (3-6) were isolated from different plant parts of Phyllanthus poilanei collected in Vietnam, with two further known analogues (7 and 8) being prepared from phyllanthusmin C (4). The structures of the new compounds were determined by interpretation of their spectroscopic data and by chemical methods, and the structure of phyllanthusmin D (1) was confirmed by single-crystal X-ray diffraction analysis. Several of these arylnaphthalene lignan lactones were cytotoxic toward HT-29 human colon cancer cells, with compounds 1 and 7-O-[(2,3,4-tri-O-acetyl)-α-L-arabinopyranosyl)]diphyllin (7) found to be the most potent, exhibiting IC50 values of 170 and 110 nM, respectively. Compound 1 showed activity when tested in an in vivo hollow fiber assay using HT-29 cells implanted in immunodeficient NCr nu/nu mice. Mechanistic studies showed that this compound mediated its cytotoxic effects by inducing tumor cell apoptosis through activation of caspase-3, but it did not inhibit DNA topoisomerase IIα activity.

4-Nitrophenyl- and 4'-nitro-1,1'-biphenyl-4-carboxylates attached to Mo2 quadruple bonds: ground versus excited state M2δ-ligand conjugation.

From the reactions between Mo2(T(i)PB)4, where T(i)PB = 2,4,6-triisopropylbenzoate and two equivalents of the carboxylic acid LH (LH = 4-nitrobenzoic acid and 4'-nitro[1,1'-biphenyl]-4-carboxylic acid) the compounds trans-M2(T(i)PB)2L2 have been prepared: I (L = 4-nitrobenzoate and M = Mo), II (L = 4'-nitro-1,1'-biphenylcarboxylate and M = Mo) and III (L = 4-nitrobenzoate and M2 = MoW). The compounds have been characterized by (1)H NMR, UV-Vis and steady state emission spectroscopy, ns and fs transient absorption spectroscopy and cyclic voltammetry. These data are compared with predictions based on electronic structure calculations on model compounds where T(i)PB is substituted for formate. Together these data indicate stronger ground-state coupling of the Mo2δ and ligand π* systems in I relative to II but this order is reversed in the photo excited S1(1)MLCT state. Attempts to prepare the W2 containing analogs were unsuccessful.

Desolvation and dehydrogenation of solvated magnesium salts of dodecahydrododecaborate: relationship between structure and thermal decomposition.

Attempts to synthesize solvent-free MgB12H12 by heating various solvated forms (H2O, NH3, and CH3OH) of the salt failed because of the competition between desolvation and dehydrogenation. This competition has been studied by thermogravimetric analysis (TGA) and temperature-programmed desorption (TPD). Products were characterized by IR, solution- and solid-state NMR spectroscopy, elemental analysis, and single-crystal or powder X-ray diffraction analysis. For hydrated salts, thermal decomposition proceeded in three stages, loss of water to form first hexahydrated then trihydrated, and finally loss of water and hydrogen to form polyhydroxylated complexes. For partially ammoniated salts, two stages of thermal decomposition were observed as ammonia and hydrogen were released with weight loss first of 14 % and then 5.5 %. Thermal decomposition of methanolated salts proceeded through a single step with a total weight loss of 32 % with the release of methanol, methane, and hydrogen. All the gaseous products of thermal decomposition were characterized by using mass spectrometry. Residual solid materials were characterized by solid-state (11)B magic-angle spinning (MAS) NMR spectroscopy and X-ray powder diffraction analysis by which the molecular structures of hexahydrated and trihydrated complexes were solved. Both hydrogen and dihydrogen bonds were observed in structures of [Mg(H2O)6B12H12]⋅6 H2O and [Mg(CH3OH)6B12H12]⋅6 CH3OH, which were determined by single-crystal X-ray diffraction analysis. The structural factors influencing thermal decomposition behavior are identified and discussed. The dependence of dehydrogenation on the formation of dihydrogen bonds may be an important consideration in the design of solid-state hydrogen storage materials.

Photoinduced intercalation and coordination of a dirhodium complex to DNA: dual DNA binding.

Two new complexes, cis-H,H-[Rh2 (OCCH3 NH)2 (LL)(CH3 CN)2 ](2+) , where LL=bpy (2, bpy=2,2'-bipyridine) and dppz (3, dppz=dipyrido[3,2-a:2',3'-c]phenazine), were prepared from the reaction of cis-H,H-[Rh2 (OCCH3 NH)2 (CH3 CN)6 ](2+) (1) with the corresponding bidentate ligand. The bpy and dppz ligands chelate to the same rhodium atom and are positioned trans to the amidato N atoms, as determined by the single crystal X-ray structure of 2. Irradiation of 2 and 3 with visible light in water results in the exchange of one CH3 CNeq ligand for an H2 O molecule with quantum yields, Φ400 , of 0.040 and 0.044, respectively (λirr =400 nm). The identities of the photoproducts of 2 and 3 were determined to be cis-H,H-[Rh2 (OCCH3 NH)2 (L)(H2 O)(CH3 CN)](2+) , where L is bpy (4) and dppz (5), respectively. Mobility shift assays show that 4 crosslinks double-stranded DNA, and ESI-MS experiments indicate that both 4 and 5 form covalent adducts with single-stranded DNA. In addition, relative viscosity and 2D NMR experiments show that the dppz ligand of 5 also intercalates into DNA upon irradiation, making 3 a dual-binding agent that both intercalates and covalently binds to DNA upon the absorption of visible light.

(E)-3-(9-Ethyl-9H-carbazol-3-yl)-1-(2-meth-oxy-phen-yl)prop-2-en-1-one.

In the title mol-ecule, C24H21NO2, the dihedral angle between the carbazole ring system [with a maximum deviation of 0.052 (2) Å] and the benzene ring is 38.6 (1)°. In the crystal, weak bifurcated (C-H)2⋯O hydrogen bonds link the mol-ecules into chains along [100].

N-[2-(9H-Carbazol-9-yl)eth-yl]-4-(methyl-sulfon-yl)aniline.

In the title mol-ecule, C21H20N2O2S, the dihedral angle between the mean plane of the carbazole ring system [maximum deviation = 0.021 (4) Å] and the benzene ring is 80.15 (6)°. In the crystal, mol-ecules are linked by N-H⋯O and weak C-H⋯O hydrogen bonds into a C(8) chain along [001].

Caeruleanone A, a rotenoid with a new arrangement of the D-ring from the fruits of Millettia caerulea.

Caeruleanone A (1), a novel rotenoid with an unprecedented arrangement of the D-ring, was isolated with another two new analogues, caeruleanones B (2) and C (3), together with 11 known rotenoids from the fruits of Millettia caerulea. The structures of the new compounds were determined by spectroscopic data analysis, with that of 1 being confirmed by single-crystal X-ray diffraction. Compounds 2 and 3 displayed potent mitochondrial transmembrane potential inhibitory and quinone reductase induction activities.

THF exchange and molecular dynamics in the series (BDI)MgX(THF), where X = Bu(n), NEt2, and OBu(t) and BDI = 2-[(2,6-diisopropylphenyl)amino]-4-[(2,6-diisopropylphenyl)imino]pent-2-ene.

The complexes (BDI)MgX(THF), where X = Bu(n), NEt2, and OBu(t), are shown to undergo THF exchange at low added concentrations of THF by a dissociative mechanism: X = Bu(n), ΔH(#) (kcal mol(-1)) = 13.4 ± 0.4 and ΔS(#) (cal mol(-1) K(-1)) = 6.3 ± 1.6; X = NEt2, ΔH(#) (kcal mol(-1)) = 15.2 ± 0.5 and ΔS(#) (cal mol(-1) K(-1)) = 11.4 ± 2.3; X = OBu(t), ΔH(#) (kcal mol(-1)) = 16.4 ± 0.3 and ΔS(#) (cal mol(-1) K(-1)) = 9.5 ± 1.3. The apparent aryl group rotations involving the BDI ligands have, within experimental error, the same activation parameters as the THF dissociation, which suggests that the two are correlated involving a three coordinate reactive intermediate akin to what is well-known for related (BDI)ZnR compounds involving three-coordinate trigonal planar Zn(2+). At higher concentrations of THF for X = Bu(n) and OBu(t), but not for X = NEt2, the coalescence temperatures for apparent aryl group rotation are depressed from those of the pure compounds in toluene-d8, and evidence is presented that this correlates with an associative interchange process which becomes dominant in neat THF. We estimate the Ia mechanism to have activation parameters: ΔH(#) (kcal mol(-1)) = 5.4 ± 0.1 and ΔS(#) (cal mol(-1) K(-1)) = -20.9 ± 0.3 for X = Bu(n) and ΔH(#) (kcal mol(-1)) = 8.3 ± 0.8 and ΔS(#) (cal mol(-1) K(-1)) = -19.8 ± 3.0 for X = OBu(t). For the complex (BDI)MgBu(n)(2-MeTHF), the dissociative exchange with added 2-MeTHF occurs more readily than for its THF analogue, as expected for the more sterically demanding Lewis base O-donor: ΔH(#) (kcal mol(-1)) = 12.8 ± 0.5 and ΔS(#) (cal mol(-1) K(-1)) = 8.6 ± 1.8. At very low temperatures in toluene-d8, restricted rotation about the Mg-O(THF) bond is observed for the complexes where X = NEt2 and OBu(t) but not for the complex where X = Bu(n). These observations, which have been determined from dynamic NMR studies, are correlated with the reactivities of these complexes in solution.

Single-site bismuth alkoxide catalysts for the ring-opening polymerization of lactide.

Salen bismuth alkoxides, where the salen ligand contains 2,4-di-tert-butylphenoxy groups and one of ethylene, cyclohexane or ortho-phenyl as a backbone have been prepared from reactions involving Bi[N(SiMe3)2]3 and the free salen ligand followed by alcoholysis (ButOH, PriOH and 2,6-But2C6H3OH). The molecular structures of the salen ligand with the cyclohexyl back-bone have been determined for the complexes salenBiCl and salenBiOC6H3-2,6-But2. The chloro compound is a dimer with chloride bridges while the phenoxide is monomeric with an unusually distorted five-coordinate geometry. The phenoxide and tert-butoxide complexes have been employed in the ring-opening polymerization of lactides (L- and rac-) to give polylactides, PLAs. With rac-LA heterotactic PLA is formed preferentially, Pr = ~0.9, in dichloromethane or toluene at room temperature. The reaction is first order in [Bi] and is notably faster than most aluminum and zinc initiators as well as tin(II) octanoate. These results are discussed in terms of a recent report on the polymerization of LA by Peptobismol® and bismuth subsalicylate.