Asymmetric Synthesis and Chiroptical Properties of Enantiopure Helical Ferrocenes

An enantiopure helical ferrocene ( R_p)-5 with five ortho-condensed aromatic rings was synthesized using a PtCl₂-catalyzed cycloisomerization of planar-chiral 2-ethynyl-1-(4-phenanthrenyl)ferrocene ( R_p)-6f, prepared in 3 steps from known enantiopure sulfinyl ferrocenyl boronic acid ( S_S, S_p)-7, as the source of planar chirality. This pentacyclic helical ferrocene showed a very high optical rotation value and strong circular dichroism (CD) signals.

Synthesis of functionalized alkyl substituted benzoquinones by Rh-catalyzed additions of boronic acids

An efficient, group tolerant one-pot process has been developed for the synthesis of functionalized-quinones, using a Rh-catalyzed addition as a key step.

Stapled helical o-OPE foldamers as new circularly polarized luminescence emitters based on carbophilic interactions with Ag(i)-sensitivity

ortho-Oligo(phenylene)ethynylenes (o-OPEs) stapled with enantiopure 2,3-dihydroxybutane diethers have highly intense circular dichroism (CD) spectra and excellent circular polarized luminescence (CPL) responses (glum values up to 1.1 × 10-2), which are consistent with homochiral helically folded structures. In the presence of Ag(i), a change in the CPL emission is observed, representing the first example of CPL active small organic molecular emitters, which can be modulated by carbophilic interactions in a reversible manner.

Glucose-functionalized amino-OPEs as biocompatible photosensitizers in PDT

Photodynamic therapy (PDT) is a minimally invasive procedure that can provide a selective eradication of neoplastic diseases by the combined effect of a photosensitizer, light and oxygen. New amino oligo(phenylene-ethynylene)s (OPEs), bearing hydrophilic glucoside terminations, have been prepared, characterized and tested as photosensitizers in PDT. The effectiveness of these compounds in combination with UVA light has been checked on two tumor cell lines (HEp-2 and HeLa cells, derived from a larynx carcinoma and a cervical carcinoma, respectively). The compounds triggered a mitotic blockage that led to the cell death, being the effect active up to 3 μm concentration. The photophysical properties of OPEs, such as high quantum yield, stability, singlet oxygen production, biocompatibility, easy cell-internalization and very good response even at low concentration, make them promising photosensitizers in the application of PDT.

Enantioselective Synthesis of Four Stereoisomers of Sulfinyl Ferrocenyl Quinones with Central, Planar, and Helical Chirality

Four stereoisomers of sulfinyl ferrocenyl-substituted helicenequinones having central, planar, and helical elements of chirality were stereoselectively formed, in one step, from reaction between enantiopure sulfinyl ferrocenyl dienes and a sulfinyl quinone. Asymmetric synthesis, kinetic resolution, or chemical resolution processes occurred in sequential cycloaddition, sulfoxide elimination, and partial aromatization steps.

Mild access to planar-chiral ortho-condensed aromatic ferrocenes via gold(i)-catalyzed cycloisomerization of ortho-alkynylaryl ferrocenes

An asymmetric gold(i)-catalyzed intramolecular hydroarylation of aquiral 2-alkynylaryl ferrocenes provides (R_p) planar-chiral ortho-condensed aromatic ferrocenes in high yield and enantioselectivity.

Novel ortho-OPE metallofoldamers: binding-induced folding promoted by nucleating Ag(i)–alkyne interactions

Ag(i)–alkyne interactions induce the folding of o-OPE foldamers, yielding a new class of metallofoldamers.

Control of the helical chirality of enantiopure sulfinyl (Z)-azobenzene-based photoswitches

A new class of enantiopure ortho,ortho-disubstituted azobenzene photoswitches has been synthesized from (S)-2-(p-tolylsulfinyl)benzoquinone and arylhydrazines. The sulfoxide acts as a unidirectional controller of the helical chirality that arises in the Z isomer after photoisomerization. Highly congested E-azobenzenes 5 c showed two atropisomeric diastereoconformers in the solid state that converged upon irradiation into a unique Z isomer with defined helicity (M), as evident in the X-ray structure. The chiroptical properties of this three-state enantiopure switch can be externally tuned both photochemically and/or thermally. Theoretical CD spectra calculated by using time-dependent DFT methods support the existence of two atropoisomeric E isomers and only one Z isomer with (M) helicity. Complementary to the classical azobenzene-based switches, the photoswiching event is promoted under green/blue light and do not occur under UV irradiation.

A retrospective 12-month study of conversion to everolimus in lung transplant recipients

BACKGROUND

Everolimus has potent antifibrotic effects that may potentially affect the clinical course of bronchiolitis obliterans syndrome (BOS) or provide nephroprotective immunosuppressive regimens for lung transplantation.

METHODS

We retrospectively assessed the 12-month outcomes of the conversion to everolimus among lung recipients in six Spanish centers.

RESULTS

From March 2005 to December 2007, 65 lung recipients who were at a mean posttransplantation time of 10.2 ± 7.9 months were converted to everolimus, mainly because of BOS (64.6%) or renal insufficiency (RI; 12.3%). The initial dose of everolimus was 1.9 ± 0.6 mg/d and the mean blood trough levels were stable over time (6.4 ± 2.8 ng/mL at 12 months). Conversion to everolimus allowed us to eliminate the calcineurin inhibitor (CNI) in 21% of patients. Among the overall population, the forced expiratory volume at 1 second (FEV(1)) and renal function remained stable. Mean FEV(1) did not change among the 35 (81%) patients surviving BOS at 12 months: preconversion FEV(1): 1.449.5 ± 641.9 mL vs 12-month FEV(1): 1420.0 ± 734.6 mL (P = .866). There was a significant improvement in renal function among the RI patients with mean glomerular filtration rates of 42.2 ± 15.2 mL/min/1.73 m(2) (P = .043) at 6 and 44.4 ± 18.8 mL/min/1.73 m(2) at 12 months, (P = .063) and a decrease in the use of CNIs from 1% of RI patients preconversion to 57% at 6 and 75% at 12 months. With a mean of 8.1- months follow-up (range: 1-31.3) overall survival was 84.6% at 1 year and 50% at 22.3 months. Progressive BOS was the main cause of death. Reasons for everolimus discontinuation were patient death (n = 10), lack of efficacy (n = 4), gastrointestinal adverse events (n = 2), and edema (n = 2).

CONCLUSIONS

BOS and RI were the main indications for conversion to everolimus among lung recipients. Conversion to everolimus improved renal function among patients converted because of RI. The present results were inconclusive regarding effects of everolimus on BOS.

Synthesis and chiroptical properties of ferrocene-[4]-helicenequinones: kinetic resolution of a planar-chiral diene

Both enantiomers of ferrocene [4]-helicenequinone 6, showing planar and helical chiralities, have been synthesized with very high optical purities using, as the key step, a kinetic resolution process between planar-chiral racemic ferrocene diene 2 and enantiopure sulfinyl benzoquinone (S)-3.

Regioselective alkylation of heteroaromatic compounds with 3-methyl-2-quinonyl boronic acids

Reactions of heteroaromatic compounds with 3-methyl substituted 2-quinonyl boronic acids proceeded by 1,4-addition followed by spontaneous protodeboronation, leading directly to the Friedel-Crafts alkylation products instead of the commonly observed alkenylation derivatives resulting from quinones. The boronic acid acts as a temporary regiocontroller, making the system a highly reactive quinone equivalent and opening a direct access to 5,5-disubstituted cyclohexene-1,4-diones.

Stereoselective synthesis of the C15-C26 fragment of the antitumor agent (-)-dictyostatin

The synthesis of the C15-C26 fragment of (-)-dictyostatin is reported in 10 steps and 28% overall yield. The key steps are the two stereoselective sulfoxide-directed processes: a Reformatsky-type reaction and a β-keto sulfoxide reduction.

Exploring Morita-Baylis-Hillman reactions of p-quinols

The Morita-Baylis-Hillman reaction of p-methylquinols with activated aromatic aldehydes has been studied. Depending on the reaction conditions (solvent and additives), three different products were formed. A mono or double Morita-Baylis-Hillman adduct and a fused 1,3-dioxolane could be obtained in good chemical yields. The use of non-nucleophilic bases to promote the reaction suggested an autocatalytic mechanism.

Stereocontrolled approach to phenyl cyclitols from (SR)-[(p-tolylsulfinyl)methyl]-p-quinol

Reactions of enantiopure (SR)-[(p-tolylsulfinyl)methyl]-p-quinol with ArAlMe(2) reagents allowed a highly diastereoselective 1,4-addition of the aryl group with an efficient desymmetrization of the prochiral cyclohexadienone moiety. The asymmetric synthesis of phenyl-substituted polyoxygenated cyclohexane derivatives was achieved by combining this reaction with a stereoselective reduction and elimination of the beta-hydroxysulfoxide, after oxidation to sulfone, to recover a carbonyl group, and a stereoselective epoxidation.

General synthesis of 8-aryl-2-tetralones

Two alternative routes are described for the synthesis of 8-aryl-2-tetralones (1). Route A starts from alpha-tetralone 3 and involves 3 or 4 steps, with the selective Na-EtOH reduction of 1-aryl-7-methoxynaphthalenes 2 being the key step. The exclusive reduction of the A ring of naphthalenes 2 occurs when the aryl group at C-1 has no substituent at the ortho positions, affording tetrahydronaphthalenes 11. Reduction of the B ring of 2 becomes the major process when the aryl fragment has two substituents at the ortho positions, affording 8-aryl-2-tetralones 1 as the major component. Route B involves 5 steps starting from 2-tetralone 5, with the key step being the Suzuki coupling with triflate 4. This approach allows the synthesis of 8-aryl-2-tetralones 1 with no substituent at the ortho positions of the aryl fragment and with naphthalene and anthracene rings at C-8.

Photoinduced Conformational Switch of Enantiopure Azobenzenes Controlled by a Sulfoxide

Two series of enantiopure azobenzenes with a p-tolylsulfoxide at the ortho or meta position with respect to the azo group, have been regioselectively synthesized. Both can act as enantiopure molecular switches showing different structural features owing to the presence of the stereogenic sulfur. The photoisomerization process, studied by UV-vis, circular dichroism (CD), NMR, and chiral HPLC evidenced a double role of the sulfoxide. A transfer of chirality from the sulfoxide to the azo system was observed by CD in both cis and trans-isomers of the meta sulfinyl derivatives 3, whereas this perturbation was evident for the ortho sulfinyl series 7 only in the cis isomer. The NMR study evidenced that the s-cis rigid conformation of the bisaromatic sulfoxide was fixing a different orientation of the overall system in each series both in the trans and cis isomers, by forcing a final U-shaped structure in cis-3 and an S-shaped structure in cis-7. Very different values of specific optical rotations were measured in both trans and cis isomers, also reflecting the existence of distinct chiral entities in the photostationary states. The easy and reversible changes occurring between different conformational states could find applications in the photocontrol of several molecular switches.

Enantioselective Synthesis of Natural Polyoxygenated Cyclohexanes and Cyclohexenes from [(p-Tolylsulfinyl)methyl]-p-quinols

Exploitation of the beta-hydroxysulfoxide fragment present in a number of enantiomerically pure (SR)- and (SS)-[(p-tolylsulfinyl)methyl]-p-quinols allowed chemo- and stereocontrolled conjugate additions of different organoaluminium reagents to the cyclohexadienone moiety. The same fragment was also shown to act as an efficient chiral masking carbonyl group, after oxidation to sulfone and retroaddition in basic medium, with elimination of methyl p-tolyl sulfone. Through the use of both transformations as key steps, enantiocontrolled syntheses of different natural products-such as the two enantiomers of dihydroepiepoformin, (-)-gabosine O, (+)-epiepoformin, (-)-theobroxide and (+)-4-epigabosine A (an epimer of the natural product gabosine A)-has been achieved. The presence of the beta-hydroxy sulfone moiety makes the cyclic structures rigid, allowing a number of stereoselective transformations such as carbonyl reductions, enone epoxidations or cis-dihydroxylations, en route to the natural structures. The observed selectivities were dependent on the particular substitution in each substrate, providing evidence of a strong influence of remote groups on the preferred approach of the reactants to the reactive conformations. An advanced precursor of natural (+)-harveynone was also synthesized, but the isolation of the natural product was not possible because of the instability of the corresponding enone, containing a triple bond, under the basic conditions necessary to eliminate the beta-hydroxy sulfone. This demonstrated that the limitations of the use of the beta-hydroxy sulfoxide as a chiral protecting carbonyl group were dependent on the relative stabilities of the final targets in the presence of the required base.

Asymmetric Synthesis of Rubiginones A2 and C2 and Their 11-Methoxy Regioisomers

Convergent enantioselective syntheses of angucyclinone-type natural products rubiginones A(2) (2) and C(2) (1) and their 11-methoxy regioisomers 3 a and 3 b have been achieved by using two domino processes from a common enantiomerically pure 1-vinylcyclohexene 4. Key steps in the synthesis of this diene were the stereoselective conjugate addition of AlMe(3) on (SS)-[(p-tolylsulfinyl)methyl]-p-quinol (9) and the elimination of the beta-hydroxy sulfoxide fragment, after oxidation to sulfone, to recover a carbonyl group. The first domino sequence comprised Diels-Alder reaction with a sulfinyl naphthoquinone followed by sulfoxide elimination. An efficient opposite regioselection in the cycloaddition step was achieved in the convergent construction of the tetracyclic skeleton using a sulfoxide at C-2 or C-3 of the dienophiles 5 or 6, derived from 5-methoxy-1,4-naphthoquinone. The second domino process, triggered by oxygen and sunlight, allowed the transformation of the initial tetracyclic adducts into the final products after B ring aromatization, silyl deprotection and C-1 oxidation.

Is gammaglobulin anti-CMV warranted in lung transplantation?

The usefulness of anti-CMV hyperimmune gammaglobulin (IgG-CMV, Cytotec) in lung transplant patients (LTx) is controversial. The objective of this study was to analyze the effectiveness of IgG-CMV in our LTx receptors.

PATIENTS AND METHODS

A retrospective study of LTx recipients treated with IgG-CMV as prophylaxis or as treatment for invasive disease. We used IgG-CMV associated with IV ganciclovir (GCV) as treatment for invasive disease. High-risk patients (CMV-negative recipients from CMV-positive donors; CMV-/+) were also with IgG-CMV prophylaxis during the first year. Other prophylactic uses of IgG-CMV were as an alternative to GCV in patients with related GCV toxicity, and as preemptive therapy in cases of persistent positive viral load (antigenemia > or = 1 cell and/or a PCR > or = 400) although oral GCV administration.

RESULTS

Between January 2000 and August 2003, 14 of the 74 lung transplant recipients (19%) received IgG-CMV as treatment for invasive disease (4 cases: 2 gastritis, 1 esophagitis, 1 hepatitis) and/or as prophylaxis (14 cases). All patients treated for invasive disease evolved favorably. No therapeutic failure were observed in CMV-/+ patients during treatment. Three of the six patients treated with IgG-CMV developed positive antigenemia despite treatment. The four patients treated for persistent antigenemia while receiving oral GCV achieved neutralization during the first month of treatment.

CONCLUSION

IgG-CMV associated with Gancyclovir is effective as treatment for invasive disease and as pre-emptive therapy in patients with persistent positive viral load. In CMV-/+ recipients, IgG-CMV prevents pneumonitis and delays the development of invasive disease after the first year.

Total Stereoselective Synthesis of (+)-Goniothalesdiol

[reaction: see text] The stereoselective synthesis of (+)-goniothalesdiol (1) was accomplished in nine steps starting from commercially available (-)-(2S,3S)-dimethyl D-tartrate (3). The key features were a completely diastereoselective reduction of a beta-ketosulfoxide to generate the stereogenic center at C-5 in 7 and formation of the 2,5-cis-substituted tetrahydrofuran ring in 10 from a stereoselective Et(3)SiH/TMSOTf-promoted reductive cyclization/deoxygenation.

Conjugate Additions of Me2CuLi to Enantiopure γ-Hydroxy-δ-sulfinyl and Sulfonyl Pentenoates

[reaction: see text] A systematic study of dimethyl cuprate conjugate additions to diastereoisomeric ethyl gamma-hydroxy (or tert-butyldimethylsilyloxy)-delta-p-tolylsulfinyl-2-pentenoates and the analoguous sulfones showed mainly 3,4-anti diastereoselectivity when the reaction occurred in the presence of TMSCl. The pi-facial diastereoselection is mainly governed by the gamma-hydroxy or silyloxy group, whereas the role of the sulfur functionality is to increase the reactivity of the pentenoate system, probably by assisting the transfer of the alkyl group from the cuprate. This was evidenced by the reactions on similar systems that lack the sulfur functions. The appropriate choice of NH4OH or HCl hydrolysis in the workup allowed direct access to the open chain products or the lactones.

[Lung transplant therapy for suppurative diseases]

OBJECTIVE

Lung transplantation is a valid therapeutic approach for patients with bronchiectasis. The objective of the present study was to evaluate our experience with bronchiectasis patients and compare the results in patients with cystic fibrosis to results in those with bronchiectasis caused by other processes.

PATIENTS AND METHOD

We carried out a retrospective study of bronchiectasis patients treated by lung transplantation in order to analyze demographic, functional and microbiological characteristics before and after transplantation, and survival.

RESULTS

From 1991 to 2002 lung transplants were performed on 171 patients, 44 of whom had suppurative lung disease (27 had cystic fibrosis and 17 had bronchiectasis caused by other processes). There were no significant differences in the demographic variables between the 2 groups. At transplantation, lung function variables showed severe bronchial obstruction (mean [SD] forced expiratory volume in 1 second of 808 [342] mL and forced vital capacity of 1,390 [611] mL) and respiratory insufficiency (PaO2 at 52 [10] mm Hg and PaCO2 at 48 [9] mm Hg). Only PaO2 was significantly lower in patients with bronchiectasis from causes other than cystic fibrosis. Airway colonization was present in 91% of the patients; Pseudomonas spp germs were detected in 64% of the cases and were multiresistant in 9%. In the early postoperative period germs were isolated in 59% of the cases, half of which involved the same germ as had been isolated before transplantation. One year after lung transplantation, 34% of the patients continued to have bronchial colonization. Survival at 1 year was 79% and at 5 years, 49%, with no significant difference between the patients with cystic fibrosis and those with other suppurative diseases, nor between the patients with and without Pseudomonas colonization. Only 2 patients had died of bacterial pneumonia at 1 month after transplantation.

CONCLUSIONS

Although airway colonization in patients with suppurative diseases complicates postoperative management, the results in terms of survival are good.