A Concise Total Synthesis of (−)-Cylindricine C through a Stereoselective Intramolecular Aza-[3 + 3] Annulation Strategy

[reaction: see text] An enantioselective total synthesis of (-)-cylindricine C is described, featuring a diastereoselective intramolecular aza-[3 + 3] annulation strategy and an interesting halohydrin formation of the C4-5 olefin for construction of C4-ketone. This work provides a unique approach to this family of natural products.

Alkene cis-dihydroxylation by [(Me3tacn)(CF3CO2)RuVI O2)]ClO4(Me(3)tacn = 1,4,7-Trimethyl-1,4,7-triazacyclononane): structural characterization of [3 + 2] cycloadducts and kinetic studies

cis-Dioxoruthenium(VI) complex [(Me(3)tacn)(CF(3)CO(2))Ru(VI)O(2)]ClO(4) (1, Me(3)tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane) reacted with alkenes in aqueous tert-butyl alcohol to afford cis-1,2-diols in excellent yields under ambient conditions. When the reactions of 1 with alkenes were conducted in acetonitrile, oxidative C=C cleavage reaction prevailed giving carbonyl products in >90% yields without any cis-diol formation. The alkene cis-dihydroxylation and C=C cleavage reactions proceed via the formation of a [3 + 2] cycloadduct between 1 and alkenes, analogous to the related reactions with alkynes [Che et al. J. Am. Chem. Soc. 2000, 122, 11380]. With cyclooctene and trans-beta-methylstyrene as substrates, the Ru(III) cycloadducts (4a) and (4b) [formula; see text] were isolated and structurally characterized by X-ray crystal analyses. The kinetics of the reactions of 1 with a series of p-substituted styrenes has been studied in acetonitrile by stopped-flow spectrophotometry. The second-order rate constants varied by 14-fold despite an overall span of 1.3 V for the one-electron oxidation potentials of alkenes. Secondary kinetic isotope effect (KIE) was observed for the oxidation of beta-d(2)-styrene (k(H)/k(D) = 0.83 +/- 0.04) and alpha-deuteriostyrene (k(H)/k(D) = 0.96 +/- 0.03), which, together with the stereoselectivity of cis-alkene oxidation by 1, is in favor of a concerted mechanism.

Palladium-catalyzed allylic transposition of (allyloxy) iminodiazaphospholidines: a formal [3,3]-aza-phospha-oxa-Cope sigmatropic rearrangement for the stereoselective synthesis of allylic amines

The synthesis of N-protected allylic amines has been achieved utilizing a palladium(II)-catalyzed, [3,3]-rearrangement of (allyloxy) iminodiazaphospholidines. This [3,3]-aza-phospha-oxa-Cope sigmatropic rearrangement reaction is thermodynamically driven by a P=N to P=O interconversion and is an alternative to the Overman rearrangement. The overall process involves the nucleophilic displacement of an allylic alcohol onto a P(III) precursor, followed by a Staudinger reaction to generate the (allyloxy) iminodiazaphospholidine precursors. Pd(II)-catalyzed [3,3]-aza-phospha-oxa-Cope rearrangement then gives a phosphoramide, which is readily hydrolyzed under acidic conditions to yield allylic amine derivatives. Pd(II) catalysis is believed to occur in a fashion analogous to that of the rearrangement of allylic imidates. The scope of racemic, diastereoselective, and enantioselective variants of this rearrangement is described. The use of chiral diamine auxiliaries in diastereoselective rearrangements is reported. Rearrangement of chiral N,N'-dimethyl cyclohexanediamine derived diazaphospholidines gives rise to phosphoramides with moderate diastereoselectivities (up to 3.5:1 dr). The same major diastereomeric product in these rearrangements was prepared irrespective of the starting allylic alcohol geometry. An enantioselective variant of the reaction was demonstrated for the rearrangement of cis-(allyloxy) iminodiazaphospholidines with cobalt oxazoline palladacycle (COP-X) catalysts (5 mol %) in high yield and enantioselectivity (up to 96% ee).

Determination of the extent of protein binding of antibiotics by means of an automated continuous ultrafiltration method

The extent of the protein binding of a drug is an important pharmacokinetic parameter. In this study, the determination of the protein binding of the antibiotics gatifloxacin, moxifloxacin, linezolid and telithromycin to bovine serum albumin (BSA) and human serum albumin (HSA) was performed by means of an automated continuous ultrafiltration method. The continuous ultrafiltration has several advantages compared to classical methods like equilibrium dialysis or discontinuous ultrafiltration. The method is appropriate for a fast determination of the extent of the protein binding of a drug. In one single experiment the calculation of the protein binding over a wide range of different drug/protein ratios is possible. Comparing the results obtained with the continuous ultrafiltration with binding data reported in literature shows good correlation and proves the reliability of the method.

Structure-activity relationship of triazafluorenone derivatives as potent and selective mGluR1 antagonists

SAR (structure-activity relationship) studies of triazafluorenone derivatives as potent mGluR1 antagonists are described. The triazafluorenone derivatives are non-amino acid derivatives and noncompetitive mGluR1 antagonists that bind at a putative allosteric recognition site located within the seven-transmembrane domain of the receptor. These triazafluorenone derivatives are potent, selective, and systemically active mGluR1 antagonists. Compound 1n, for example, was a very potent mGluR1 antagonist (IC50 = 3 nM) and demonstrated full efficacy in various in vivo animal pain models.

Design, Synthesis, and Biological Activity of Novel Polycyclic Aza-Amide FKBP12 Ligands

Since the discovery that FK-506 promotes neurite outgrowth, considerable attention has been focused on the development of potent nonimmunosuppressive ligands for FK-506 binding proteins (FKBPs). Such neuroimmunophilin agents have been reported to show neuroregenerative activity in a variety of cell and animal models including neurite outgrowth, age-related cognitive decline, Parkinson's disease, peripheral nerve injury, optic nerve degeneration, and diabetic neuropathy. We have designed and synthesized a unique series of tetracyclic aza-amides that have been shown to be potent FKBP12 rotamase inhibitors. The structure-activity relationships established in this study have demonstrated diverse structural modifications that result in potent rotamase inhibitory activity.

aza-Prins-pinacol approach to 7-azabicyclo[2.2.1]heptanes and ring expansion to [3.2.1]tropanes

[reaction: see text] The 7-azabicyclo[2.2.1]heptane ring system can be rapidly accessed from 5-(1-hydroxyallyl)-2-alkoxy-N-tosylpyrrolidines via an unusual aza-Prins-pinacol reaction mediated by Lewis acid. The products can undergo ring expansion to isomeric tropanones. These reactions show promise for a concise entry to biologically relevant azabicyclic targets.

O2 and CO Binding to Tetraaza-Tripodal-Capped Iron(II) Porphyrins

A series of tris(2-aminoethylamine) (tren) capped iron(II) porphyrins has been synthesized and characterized and their affinities for dioxygen and carbon monoxide measured. The X-ray structure of the basic scaffold with nickel inserted in the porphyrin is also reported. All the ligands differ by the nature of the group(s) attached to the secondary amine functions of the cap. These various substitutions were introduced to probe if a hydrogen bond with these secondary amine groups acting as the donor could rationalize the high affinity of these myoglobin models. This work clearly indicates that the cage structure of the tren predominates over all the other appended groups with the exception of p-nitrophenol.

Concise synthesis of 3,7-dioxa-9-aza-bicyclo[3,3,1]-nonane

[reaction: see text] The basicity of an amine has a great impact on physicochemical properties and pharmacokinetics. To attenuate the basicity of morpholine, a bicyclic amine was designed and synthesized with the introduction of an additional beta-oxygen. A transannular cyclization and reduction of a bridgehead alpha-chloro amine functionality produces the topographically unusual amine (pKa = 6.7) in good yield.

Synthetic studies on heterocyclic natural products

This article reviews past and ongoing research in the author's laboratory directed toward the synthesis of natural products displaying an azaspirocyclic framework, or incorporating a medium-ring nitrogen heterocycle. New synthetic technologies were devised in order to address the synthetic problems posed by the target molecules. Thus, efforts in the area of azaspirocyclic substances have relied on an oxidative amidation of phenols promoted by iodobenzene diacetate, whereas access to medium-ring nitrogen heterocycles has been secured by means of a ring expansion sequence that relies on the fragmentation of an aziridine triggered by a homo-Brook transposition. Details of the development of these technologies are presented, together with applications to the total synthesis of FR-901483, TAN-1251C, cylindricines, and mitomycinoids.

Preclinical and clinical pharmacology of DOV 216,303, a "triple" reuptake inhibitor

DOV 216,303 [(+/-)-1-(3,4-dichlorophenyl)-3-azabicyclo-[3.1.0]hexane hydrochloride] is the prototype of a class of compounds referred to as "triple" reuptake inhibitors. Such compounds inhibit the reuptake of norepinephrine (NE), serotonin (5-HT), and dopamine (DA), the three neurotransmitters most closely linked to major depressive disorder. DOV 216,303 inhibits [(3)H]NE, [(3)H]5-HT, and [(3)H]DA uptake to the corresponding human recombinant transporters (expressed in HEK 293 cells) with IC(50) values of approximately 20, 14, and 78 nM, respectively. DOV 216,303 is active in tests predictive of antidepressant activity including the mouse forced swim test and reversal of tetrabenazine-induced ptosis and locomotor depression. The pharmacodynamic, pharmacokinetic, and toxicological profile of DOV 216,303 in animals prompted us to initiate clinical studies. In both single and multiple dose studies using normal volunteers, DOV 216,303 was safe and well-tolerated. Furthermore, both C(max) and AUC values were dose-proportional between 5-150 mg. The plasma concentrations of DOV 216,303 at doses >10 mg were in excess of the IC(50) values for inhibition of biogenic amine reuptake. In a Phase II study designed to explore the safety and tolerability of DOV 216,303 in depressed individuals, patients received either 100 mg DOV 216,303 (50 mg b.i.d.) or 40 mg citalopram (20 mg, b.i.d.) for two weeks. A placebo arm was not employed in this study because several institutional review boards required administration of an active control to severely depressed individuals. Time dependent reductions in HAM-D scores (the primary outcome measure) were observed in both the DOV 216,303 and citalopram groups compared to baseline scores (p < 0.0001). The side effect profile was not remarkably different between treatment arms. These findings provide preliminary evidence of a clinically meaningful antidepressant action with a molecule capable of inhibiting the three transmitters most closely linked to major depressive disorder.

Structurally similar diazenes exhibit significantly different biological activity

We have previously synthesized various diazenecarboxamides (subsequently referred to as diazenes) that were cytotoxic to several tumor cell lines. To increase their biological activity, the structure has been modified appropriately. In the present study we examined the effects of N(1)-phenyl-N(2)-(2-pyridinylmethyl)diazenedicarboxamide (RL-337) obtained from the previously examined cytotoxic compound N(1)-phenyl-N(2)-(2-pyridinyl)diazenecarboxamide (JK-279), and compared them with those of diazene JK-279. Using a modified colorimetric MTT assay, the cytotoxicity of RL-337 was determined on human cervical carcinoma HeLa cells, glioblastoma A1235 cells, and prostate adenocarcinoma PC-3 cells. The possible synergistic effect of diazene RL-337 with cisplatin, doxorubicin, and vincristine, and its influence on intracellular GSH content was examined on HeLa cells. Diazene RL-337 was cytotoxic against all three human tumor cell lines, being more cytotoxic to HeLa cells than diazene JK-279. The higher efficacy of RL-337 than of JK-279 can be connected with higher basicity of the 2-picoline moiety present in the former diazene comparing with the pyridine fragment that is a part of the latter. The diazene RL-337 acted synergistically with cisplatin, doxorubicin, and vincristine (diazene JK-279 exhibited synergistic effect only with cisplatin). Glutathione (determined by Tietze's method) was not a target molecule of diazene RL-337 (but was for JK-279, as shown earlier). After just 1 h treatment with diazene RL-337, the cells started to lose membrane integrity. There was no cleavage of caspase-3 in RL-337-treated samples, and the majority of cells died 6 h after the treatment through necrosis (previously, apoptosis-like cell death was detected for diazene JK-279). Thus, although diazenes JK-279 and RL-337 are very similar in their structure, they exhibit widely different biological activity.

Aza-analogues of the marine pyrroloquinoline alkaloids wakayin and tsitsikammamines: Synthesis and topoisomerase inhibition

Two aza-analogues of the marine pyrroloquinoline alkaloids wakayin and tsitsikammamines A and B have been synthesized. The strategy used was based on a 1,3-dipolar cycloaddition reaction between indole 4,7-dione and a diazo-aminopropane derivative. One of the two analogues partially inhibits human topoisomerase I, whereas synthetic intermediates inhibit the enzyme DNA cleavage activity at a concentration comparable to that of the control drug camptothecin.

Stability Indicating Methods for the Determination of Some Fluoroquinolones in the Presence of Their Decarboxylated Degradates

Two stability-indicating methods, namely densitometric TLC and derivative spectrophotometry for the determination of the fluoroquinolone antibacterials lomefloxacin (Lfx), moxifloxacin (Mfx), and sparfloxacin (Sfx) in the presence of their acid degrades are described. Acid degradation was adopted and the main decarboxylated product separated by TLC. Degradation products were identified confirming a previously mentioned degradation scheme. The densitometric method is based on the separation of the intact drug from its acid degradation product on silica gel G plates using different mobile phases and the spots of the intact drugs were scanned at 288, 290, and 292 nm for Lfx, Mfx, and Sfx, respectively. The derivative spectrophotometric method utilizes first derivative D(1) UV spectrophotometry with zero crossing points at 295.2 nm for Lfx, 280.4 and 303.4 nm for Mfx, and 280.8 nm for Sfx. Regression analysis of Beer's plots showed good correlation in the concentration ranges 0.2-1.2, 0.1-1.4, and 0.5-2.0 microg/spot for Lfx, Mfx, and Sfx, respectively, in the densitometric method and 2-16 microg/ml for all drugs in the derivative spectrophotometric method. The proposed methods were successfully applied for the determination of the investigated drugs in bulk powder with mean percentage accuracy ranges from 98.93 to 101.25% for the TLC method and from 98.18 to 100.35% for the D(1) method. The proposed methods were also applied for the determination of the investigated drugs in their pharmaceutical dosage forms and their validity was assessed using the standard addition technique with mean percentage recovery ranging from 100.25 to 101.70% in the TLC method and from 99.27 to 102.12% in the D(1) method. The selectivity of the proposed methods was tested by the analysis of laboratory-prepared mixtures containing different percentages of the studied drugs and their acid degrades. The proposed methods were found selective for the determination of the intact drugs in the presence of up to 90% of their degrades in the TLC method and 70% for Lfx and 90% for Mfx and Sfx in the D(1) method.

Monomeric lithium triazapentadienyl complexes

Treatment of 1,3,5-triazapentadienes [N{(C3F7)C(Mes)N}2]H and [N{(C3F7)C(Dipp)N}2]H (where Mes = 2,4,6-Me3C6H2; Dipp = 2,6-Pr(i)2C6H3) with n-BuLi in hexane, followed by the crystallization from hexane-THF mixture afforded the corresponding lithium 1,3,5-triazapentadienyl complexes as their THF solvates. X-Ray crystallographic analyses revealed that [N{(C3F7)C(Mes)N}2]Li(THF)2 and [N{(C3F7)C(Dipp)N}2]Li(THF) are monomeric in the solid state. [N{(C3F7)C(Mes)N}2]Li(THF)2 has a four-coordinate lithium center with a distorted tetrahedral geometry, and features a boat-shaped C2N3Li metallacycle. [N{(C3F7)C(Dipp)N}2]Li(THF) has a three-coordinate lithium atom and a planar, U-shaped C2N3 ligand backbone. The synthesis, solid-state structure, and 1H and 19F NMR spectroscopic details of [N{(C3F7)C(Mes)N}2]H are also reported.

[Study of antituberculous activity of moxifloxacin conjugate with macrophage scavenger-receptor ligand]

Mycobacterium tuberculosis is an intracellular pathogen that persists in macrophages of the human host. An approach to improving the treatment of tuberculosis is target delivery of antibiotics to macrophages using ligands to macrophage receptors. The antituberculous activity of the conjugate of the antituberculous antibiotic moxifloxacin with carboxymethylglucan was studied in vitro using the J774 macrophage cell line and peritoneal macrophages. The antituberculous activity of the conjugate was higher than of the free moxifloxacin. The target antibiotic delivery to macrophage cells in tuberculosis infection was shown perspective.

Ultrasound-assisted liquid-phase microextraction and high-performance liquid chromatographic determination of nitric oxide produced in PC12 cells using 1,3,5,7-tetramethyl-2,6-dicarbethoxy-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacene

To reveal the function of nitric oxide (NO) that has been reported as an intracellular second messenger and a diffusible intercellular messenger, a novel ultrasound-assisted liquid-phase microextraction (ULPME) and high-performance liquid chromatographic method for the determination of NO produced in PC12 cells has been developed. 1,3,5,7-Tetramethyl-2,6-dicarbethoxy-8-(3',4'-diaminophenyl)-difluoroboradiaza-s-indacene (DAMBO-CO(2)Et) has been used for NO trapping to form corresponding triazole (DAMBO-CO(2)Et-T). The enrichment factor of DAMBO-CO(2)Et-T reached 150 in 2.5 min with the proposed ULPME method. NO produced in (200+/-5) PC12 cells has been determined directly with the detection limit (S/N=3) of 2.5 x 10(-13)mol/L (5a mol), which was the lowest in HPLC determination of NO reported yet. The proposed method was sensitive, selective, convenient and rapid, which has great prospect in the qualitative and quantitative determination of NO in minimal biological samples.

Synthesis and reactivity of a 9-membered azaenediyne: importance of proximity effect in N-alkylation

Synthesis of a 9-membered azaenediyne has been achieved for the first time via intramolecular N-alkylation; the importance of proximity of the reacting centres via cobalt carbonyl complexation of the acetylenic moiety and not the activation of propargylic carbon has been demonstrated.

T cell-mediated hypersensitivity to quinolones: mechanisms and cross-reactivity

BACKGROUND

Quinolones are widely used, broad spectrum antibiotics that can induce immediate- and delayed-type hypersensitivity reactions, presumably either IgE or T cell mediated, in about 2-3% of treated patients.

OBJECTIVE

To better understand how T cells interact with quinolones, we analysed six patients with delayed hypersensitivity reactions to ciprofloxacin (CPFX), norfloxacin (NRFX) or moxifloxacin (MXFX).

METHODS

We confirmed the involvement of T cells in vivo by patch test and in vitro by means of the lymphocyte proliferation test (LTT). The nature of the drug-T cell interaction as well as the cross-reactivity with other quinolones were investigated through the generation and analysis (flow cytometry and proliferation assays) of quinolone-specific T cell clones (TCC).

RESULTS

The LTT confirmed the involvement of T cells because peripheral blood mononuclear cells (PBMC) mounted an enhanced in vitro proliferative response to CPFX and/or NRFX or MXFX in all patients. Patch tests were positive after 24 and 48 h in three out of the six patients. From two patients, CPFX- and MXFX-specific CD4(+)/CD8(+) T cell receptor (TCR) alphabeta(+) TCC were generated to investigate the nature of the drug-T cell interaction as well as the cross-reactivity with other quinolones. The use of eight different quinolones as antigens (Ag) revealed three patterns of cross-reactivity: clones exclusively reacting with the eliciting drug, clones with a limited cross-reactivity and clones showing a broad cross-reactivity. The TCC recognized quinolones directly without need of processing and without covalent association with the major histocompatability complex (MHC)-peptide complex, as glutaraldehyde-fixed Ag-presenting cells (APC) could present the drug and washing quinolone-pulsed APC removed the drug, abrogating the reactivity of quinolone-specific TCC.

CONCLUSION

Our data show that T cells are involved in delayed immune reactions to quinolones and that cross-reactivity among the different quinolones is frequent.

PET modulated fluorescent sensing from the BF2 chelated azadipyrromethene platform

A convergent building block synthesis has been applied to new off/on photoinduced electron transfer (PET) modulated fluorescent sensors which are based on a BF(2) chelated tetraarylazadipyrromethene platform and operate in the biomedically important red region of the visible spectrum. Incorporation of diethylamine and morpholine receptors facilitates off/on microenvironment polarity and pH sensing. Aqueous formulation and in vitro cellular imaging demonstrates their potential for intracellular sensing.

Cadmium-113 NMR studies on homoleptic complexes containing thioether ligands: the crystal structures of [Cd([12]aneS4)2](ClO4)2, [Cd([18]aneS4N2)](PF6)2 and [Cd([9]aneS3)2](PF6)2

We report the measurement of 113Cd NMR chemical shift data for homoleptic thioether and related aza and mixed aza/thiacrown complexes. In a series of Cd(II) complexes containing trithioether to hexathioether ligands, we observe solution 113Cd NMR chemical shifts in the range of 225 to 731 ppm. Upfield chemical shifts in these NMR spectra are seen whenever: (a) the number of thioether sulfur donors in the complex is decreased, (b) a thioether sulfur donor is replaced by a secondary nitrogen donor, or (c) the size of the macrocycle ring increases without a change in the nature or number of the donor atoms. Changes in the identity of non-coordinating anions such as perchlorate or hexafluorophosphate have little effect upon the 113Cd NMR chemical shift in solution. We report the X-ray structure of the complex [Cd([12]aneS4)2](ClO4)2 ([12]aneS4 = 1,4,7,10-tetrathiacyclododecane) (1) which shows the first example of octakis(thioether) coordination of a metal ion, forming an unusual eight-coordinate square antiprismatic structure. We report the X-ray structure of the complex [Cd([9]aneS3)2](PF6)2 ([9]aneS3 = 1,4,7-trithiacyclononane) (3a) which shows hexakis(thioether) coordination to form a distorted octahedral structure. We have also prepared and characterized the Cd(II) complex of a mixed azathiacrown, [Cd([18]aneS4N2)](PF6)2 ([18]aneS4N2 = 1,4,10,13-tetrathia-7,16-diazacyclooctadecane) (6). Its X-ray structure shows a distorted octahedral S4N2 environment around the Cd(II) with the ligand coordinated in the rac fashion. We observe a solvent- and temperature-dependent 14N-1H coupling in the 1H NMR spectrum of the complex which is not present in analogous complexes with this ligand.

Aza-retinoids as novel retinoid X receptor-specific agonists

A new structurally simple series of potent lipophilic aza-retinoids RXR agonists has been developed. SAR studies for the N-alkyl-azadienoic acids described here demonstrate that the RXR activity profile is sensitive to the N-alkyl chain length. Further, we have expanded the work to include azadienoic acids, which exhibited many accessible conformations leading to a better understanding of the SAR around the series.

Conformation of Nα-Substituted Hydrazino Acetamides in CDCl3, the Precious Help of the Analysis of Δδ between Amidic Hydrogens, and Correlation to the Conformation of Aza-β3-peptides

[structures: see text] We studied the conformation of a series of primary amides in a solution of chloroform. Classical NMR tools such as dilution experiments, influence of DMSO, and 2D-NOESY, together with X-ray diffraction, were combined with an analysis of the difference of the chemical shift Deltadelta between the geminal amidic protons. This study was addressed in order to understand the conformation adopted by hydrazino acetamides 1a and 1b as model compounds for aza-beta3-peptides. In this manner, it was possible to show that the amidic group of these compounds acts as a H-bond donor and interacts with two different H-bond acceptors. We concluded that the hydrazinoturn, a specific bifurcated H-bond system observed in the solid state, is also the preferred conformation of hydrazino acetamides 1a and 1b in solution. Our results show that the short-range interaction with the N(alpha)-nitrogen lone pair not only stabilizes the C8 pseudocycle but could also contribute to the folding process of aza-beta3-peptides. In light of this, it could explain why aza-beta3-peptides develop a different H-bond network in comparison to their isosteric beta3-peptides analogues. Our work is in keeping with the recent interest of hydrazino peptides as an extension of the beta-peptide concept.

Lewis acid-Lewis acid heterobimetallic cooperative catalysis: mechanistic studies and application in enantioselective aza-Michael reaction

The full details of a catalytic asymmetric aza-Michael reaction of methoxylamine promoted by rare earth-alkali metal heterobimetallic complexes are described, demonstrating the effectiveness of Lewis acid-Lewis acid cooperative catalysis. First, enones were used as substrates, and the 1,4-adducts were obtained in good yield (57-98%) and high ee (81-96%). Catalyst loading was successfully reduced to 0.3-3 mol % with enones. To broaden the substrate scope of the reaction to carboxylic acid derivatives, alpha,beta-unsaturated N-acylpyrroles were used as monodentate, carboxylic acid derivatives. With beta-alkyl-substituted N-acylpyrroles, the reaction proceeded smoothly and the products were obtained in high yield and good ee. Transformation of the 1,4-adducts from enones and alpha,beta-unsaturated N-acylpyrroles afforded corresponding chiral aziridines and beta-amino acids. Detailed mechanistic studies, including kinetics, NMR analysis, nonlinear effects, and rare earth metal effects, are also described. The Lewis acid-Lewis acid cooperative mechanism, including the substrate coordination mode, is discussed in detail.

Aza-bicyclic amino acid carboxamides as α4β1/α4β7 integrin receptor antagonists

A series of N-carboxy, N-alkyl, and N-carboxamido azabicyclo[2.2.2]octane carboxamides were prepared and assayed for inhibition of alpha4beta1-VCAM-1 and alpha4beta7-MAdCAM-1 interactions. Potency and alpha4beta1/alpha4beta7 selectivity were sensitive to the substituent R1-R3 in the structures 6, 7, and 8. Several compounds demonstrated low nanomolar balanced alpha4beta1/alpha4beta7 in vitro activity. Two compounds were selected for in vivo leukocytosis studies and demonstrated increases in circulating lymphocytes up to 250% over control.