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The enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand has received considerable attention. Hydroxylamine-based chiral ligands with amide and hydroxyl functions in the presence of other co-ordinating groups are highly effective in these asymmetric reductions. The current work presents a simple one step synthesis of a series of β-hydroxyamide-based ligands from the reaction between 3-hydroxy-2-naphthoic acid and chiral amino alcohols and their applications as catalysts in asymmetric borane-mediated reductions of aromatic prochiral ketones in THF. The reductions provided the corresponding secondary alcohols with up to 96% ee and in good to excellent yields (89–99%). DFT calculations at B3LYP/6-31+g(d) level offered theoretical models to account for the enantioselectivity imposed by the chiral ligands in the reductions of the ketones.

The enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand has received considerable attention. Hydroxylamine-based chiral ligands with amide and hydroxyl functions in the presence of other co-ordinating groups are highly effective in these asymmetric reductions. The current work presents a simple one step synthesis of a series of β-hydroxyamide-based ligands from the reaction between 3-hydroxy-2-naphthoic acid and chiral amino alcohols and their applications as catalysts in asymmetric borane-mediated reductions of aromatic prochiral ketones in THF. The reductions provided the corresponding secondary alcohols with up to 96% ee and in good to excellent yields (89–99%). DFT calculations at B3LYP/6-31+g(d) level offered theoretical models to account for the enantioselectivity imposed by the chiral ligands in the reductions of the ketones.

Hydroxyamide-based ligands have occupied a considerable place in asymmetric synthesis. Here we report the synthesis of seven β-hydroxyamide-based ligands from the reaction of 2-hydroxynicotinic acid with chiral amino alcohols and test their effect on the enantioselective reduction of aromatic prochiral ketones with borane in tetrahydofuran (THF). They produce the corresponding secondary alcohols with up to 76% enantiomeric excess (ee) and good to excellent yields (86-99%).

Asymmetric transfer hydrogenation processes of ketones with chiral molecular catalysts are attracting increasing interest from synthetic chemists due to their operational simplicity. C-2-symmetric catalysts have also received much attention and been used in many reactions. A series of new chiral C-2-symmetric bis(phosphinite) ligands has been prepared from corresponding amino acid derivated amino alcohols or (R)-2-amino-1-butanol through a three- or four-step procedure. Their structures have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy and elemental analysis. H-1-P-31 NMR, DEPT, H-1-C-13 HETCOR or H-1-H-1 COSY correlation experiments were used to confirm the spectral assignments. In situ prepared ruthenium catalytic systems were successfully applied to ruthenium-catalyzed asymmetric transfer hydrogenation of acetophenone derivatives by iso-PrOH. Under optimized conditions, these chiral ruthenium catalyst systems serve as catalyst precursors for the asymmetric transfer hydrogenation of acetophenone derivatives in iso-PrOH and act as good catalysts, giving the corresponding optical secondary alcohols in 99% yield and up to 79% ee. (C) 2012 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

Chiral ruthenium catalyst systems generated in situ from [Ru(η6-p-cymene)(μ-Cl)Cl]2 complex and chiral C 2-symmetric bis(phosphinite) ligands based on amino alcohol derivatives were employed in the asymmetric transfer hydrogenation of aromatic ketones to give the corresponding optically active alcohols in high yield. The best results were obtained in the [Ru(η6-p-cymene)­(μ-Cl)Cl]2 and (2S)-2-[benzyl(2-{benzyl[(2S)-1-[(diphenylphosphanyl)oxy]-3-phenyl propan-2-yl]amino}ethyl)amino]-3-phenylpropyl diphenylphosphinite or (2R)-2-[benzyl(2-{benzyl[(2R)-1-[(diphenyl­phosphanyl)oxy]-3-phenylpropan-2-yl]amino}ethyl)amino]-3-phenylpropyl diphenylphosphinite catalytic systems, which gave enantioselectivities of up to 93% ee and 99% conversion.

Enantioselective reduction of prochiral ketones to optically active secondary alcohols is an important subject in synthetic organic chemistry because the resulting chiral alcohols are extremely useful, biologically active compounds. The new chiral ligands (2R)-2-[benzyl{(2-((diphenylphosphanyl)oxy)ethyl)}amino]butyldiphenylphosphinite, 1 and (2R)-2-[benzyl{(2-((dicyclohexylphosphanyl)oxy)ethyl)}amino]butyldicyclohexylphosphinite, 2 and the corresponding ruthenium(II) complexes 3 and 4 have been prepared. The structures of these complexes have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy and elemental analysis. 31P–{1H} NMR, DEPT, 1H–13C HETCOR or 1H–1H COSY correlation experiments were used to confirm the spectral assignments. These ruthenium(II)–phosphinite complexes have been used as catalysts for the asymmetric transfer hydrogenation of acetophenone derivatives. Under optimized conditions, aromatic ketones were reduced in good conversions and in moderate to good enantioselectivities (up to 85% ee).

Hydrogen transfer reduction processes are attracting increasing interest from synthetic chemists in view of their operational simplicity. Reaction of [Ph2PNHCH2-C4H3S] with [Ru(η6-benzene)(µ-Cl)Cl]2, [Rh(µ-Cl)(cod)]2 and [Ir(η5-C5Me5)(µ-Cl)Cl]2 gave a range of new monodendate complexes [Ru(Ph2PNHCH2-C4H3S)(η6-benzene)Cl2], 1, [Rh(Ph2PNHCH2-C4H3S)(cod)Cl], 2, and [Ir(Ph2PNHCH2-C4H3S)(η5-C5Me5)Cl2], 3, respectively. All new complexes were fully characterized by analytical and spectroscopic methods. 1H31P NMR, 1H13C HETCOR or 1H1H COSY correlation experiments were used to confirm the spectral assignments. 1–3 are suitable catalyst precursors for the transfer hydrogenation of acetophenone derivatives. Notably [Ru(Ph2PNHCH2-C4H3S)(η6-benzene)Cl2], 1, acts as an excellent catalyst, giving the corresponding alcohols in 98–99% yields in 30 min at 82 °C (TOF ≤200 h−1) for the transfer hydrogenation reaction in comparison to analogous rhodium or iridium complexes. This transfer hydrogenation is characterized by low reversibility under these conditions. Copyright © 2011 John Wiley & Sons, Ltd.

A series of β-amino alcohols derivatives were synthesized from (R)-2-amino-1-butanol and (S)-1,2-propanediol, and they have been used as organocatalaysts in the racemic ring opening of epoxide in good yields with high enantiomeric excess (up to 97%).

Hydrogen-transfer reduction processes are attracting increasing interest from synthetic chemists in view of their operational simplicity. The new chiral C 2 -symmetric ligands N,N ′-bis-[(1 S )-1- sec -butyl-2- O- (diphenylphosphinite)ethyl]ethanediamide, 1 and N,N′ -bis-[(1 S )-1-phenyl-2- O -(diphenylphosphinite)ethyl]ethanediamide, 2 and the corresponding ruthenium complexes 3 and 4 have been prepared and their structures have been elucidated by a combination of multi-nuclear NMR spectroscopy, IR spectroscopy, and elemental analysis. 1 H– 31 P NMR, DEPT, 1 H– 13 C HETCOR, or 1 H– 1 H COSY correlation experiments were used to confirm the spectral assignments. The catalytic activity of complexes 3 and 4 in transfer hydrogenation of acetophenone derivatives by iso- PrOH has also been studied. Under optimized conditions, these chiral ruthenium complexes serve as catalyst precursors for the asymmetric transfer hydrogenation of acetophenone derivatives in iso -PrOH and act as excellent catalysts, giving the corresponding chiral alcohols in 99% yield and up to 75% ee. This transfer hydrogenation is characterized by low reversibility under these conditions.

Environmental law has emerged under the influence of ecology as a distinct branch of law. Indeed there is a co-evolution process between these two disciplines which rests on a common basis derived from the challenges what is described here as the ‘environmental problematic’ to the established relationships between human being and nature. This article evaluates the subject taking into consideration generally accepted facts and principles in ecology, whilst avoiding scientific details and discussions. Environmental law is also considered not in the sense of sector-based environmental legislation but in a general conceptual framework common for all countries and based on sociological as well as ethical aspects. In consequence the article underlines new themes which are not familiar in the traditional positive law concept. The influence of ecology on the aim, scope, approach, characteristics and concepts of environmental law, which are different from traditional concepts of law, are explained before reaching a conclusion. Although law and ecology are mainly reviewed the explanations also point out the significant role of other disciplines such as economics, politics and ethics.

Purpose: Describing the ophthalmic findings of an exudative vasculopathy called as Coats-like retinitis pigmentosa on three patients. The etiology of the Coats-like retinitis pigmentosa is obscure. The principal theories have been discussed in this article. Methods: Three observational case series have been discussed. Complete ophthalmic examinations and color fundus photos, visual field, and fluorescein angiography have been performed. Results: We have identified 3 patients who have some typical clinical features of Coats-like retinitis pigmentosa; peripheral serous retinal detachment, telangiectasia, prominent lipid deposition, pigmentary changes in peripheral retina, and loss of vision. None of the three patients had positive family history. All of the patients have had symptoms of nyctalopia, decreased central vision, and two of them have had constriction of visual field. All of the patients have had cataracts and two of them underwent cataract surgery. Fundus examination and fluorescein angiography of patients revealed typical retinitis pigmentosa with Coats-type changes in bilateral inferiotemporal quadrants. Conclusion: A better understanding of clinical features and genetic etiology of Coats-type retinitis pigmentosa will aid diagnosis and development of new therapies. If sufficient conditions arise, genetic factors that influence the expression of CRB1 mutations in Coats-like retinitis pigmentosa should be detected.

The work involves an experimental ((1)H NMR) and theoretical (MD, MM-PBSA and DFT) investigation of the molecular recognition and discrimination properties of a chiral aza-15-crown-5 against methyl esters of alanine, phenylalanine and valine hydrochloride salts. The results indicate that the receptor binds enantiomers with moderate binding constants (88-1,389 M(-1)), with phenylalanine being more discriminated. The difference in experimental binding free energies (ΔG(R) - ΔG(S)) for alanine, phenylalanine and valine enantiomers were calculated as -0.36, -1.58 and 0.80 kcal mol(-1), respectively. The differences in theoretical binding energies were calculated by MM-PBSA (ΔE(R)PB - ΔE(S)PB=) as -0.30, -1.45 and 0.88, by B3LYP/6-31+G(d) as -1.17, -0.84 and 0.74 and by M06-2X/6-31+G(d) as -1.40, -3.26 and 1.66 kcal mol(-1). The data obtained give valuable information regarding the molecular recognition mode of the organoammonium complexes of chiral aza-crown ether with C 1 symmetry, which may be relevant to biological systems.

New chiral diaza-18-crown-6 ether derivatives, 5 and 6 were synthesized from (R)-(-)-2-amino-1-butanol. These chiral artificial receptors exhibit pronounced chiral recognition toward the enantiomers of l- and d- amino acid derivatives. The highest enantioselectivity was observed in the case of Trp-OMe·HCl (K D /K L =12.5).

Some new chiral Schiff bases have been prepared in good yields from various carbonyl groups and two 2-amino alcohols. LiAlH 4 was treated with different equivalents of the Schiff bases. Enantioselective reduction of acetophenone is achieved in high chemical yield (up to 93%) with moderate enantiomeric excess (up to 22%) by use of the new reducing agents.

A variety of aliphatic 1,3‐diols (4a–c, 5a–c, 6a–c) was synthesized from β‐hydroxy carbonyl compounds (1–3) for potential use in the solvent extraction of boron. Primary‐secondary and primary‐tertiary alcohol structures of 1,3‐diols substituted with isopropyl, isobutyl, and isopentyl groups have been demonstrated to be very efficient for the solvent extraction of boric acid from aqueous solutions. The extraction ability of 2,2,5‐trimethyl‐1,3‐hexanediol (5b) was investigated as a function of 5b concentration, solution pH, solvent properties, and stripping conditions. Extraction efficiency increased with increasing concentration of 5b, and the best extraction of boron (96.8%) was found to be at an equilibrium pH of 2 with 0.5 M of 5b. Chloroform, toluene, chlorobenzene, 2‐octanol, and n‐amyl alcohol were found to be suitable solvents for the solvent extraction of boron. The boron complex can be recovered from the organic phase by treatment with an aqueous solution of sodium hydroxide. The highest ...

A practical synthesis of chiral monoaza-15-crown-5 ethers 1 and 2 has been achieved from l -valinol. The molecular recognition by these chiral crown ethers for ( RS )-α-phenylethylamine, ( RS )-α-(1-naphthyl)ethylamine and their perchlorate salts has been characterized by UV–vis.

Four novel C 2 -symmetric macrocyclic compounds with a pyridine function and possessing amide and ester lingeages were prepared. The enantiomeric discrimination abilities of these macrocycles against α-phenylethylammonium and α-(1-naphthyl)ethylammonium perchlorate salts were measured by standard 1 H NMR titration techniques in DMSO- d 6 . A binding constant ratio of 31 (Kbind(S)/Kbind(R)) for two enantiomers of α-(1-naphthyl)ethylammonium salt with the macrocyclic host ( S , S )- 4 bearing phenyl arms was observed, which corresponds to an enantiomeric discrimination of approximately 94%. Molecular dynamic calculations were performed for some of the supramolecular complexes to in order to gain insight into the mode of molecular recognition between the macrocyclic compounds and ammonium salts; these results were consistent with experimental observations, which may be relevant to those in biochemical processes occurring in organisms.

Objective: To evaluate the central corneal thickness (CCT) in patients with diabetes mellitus (DM) and healty control subjects. Materials and Methods: A hundred eyes of fifty patients with DM followed up in our clinic were investigated in the study. The diabetics were divided into two groups as having diabetic retinopathy (group 1, 19 patients) and not (group 2,31 patients), and a hundred eyes of 50 non-diabetic, healty subjects were classified as control group (group 3). All the patients SKK was measured via ultrasonic pachymeter (Optopol, Echoson Demsin M, Poland) under topical anesthesia. Results: The mean CCT was found as 548.94±37.13 µm in patients with DM; 533.45±43.38 µm in healty control group. The difference between diabetic patients and healty subjects was statistically significiant (p < 0.05). The mean CCT in patients with diabetic retinopathy (group 1) was 558.39±29.8 µm, and in non-diabetic retinopathy group (group 2), the mean CCT was found 543.14±40.1 µm. The difference between group 1 and 2 was statistically significiant (p, Amaç: Diyabetes mellituslu (DM) hastalarda ve sağlıklı bireylerde santral kornea kalınlığının (SKK) değerlendirilmesi. Gereç ve Yöntemler: Diyabetes mellitus tanısı ile kliniğimizde diyabetik retinopati açısından takip edilen 50 hastanın 100 gözü çalışma kapsamına alındı. Hastalar diyabetik retinopatisi olan (grup 1, 19 hasta) ve diyabetik retinopatisi olmayan (grup 2, 31 hasta) olarak iki gruba ayrıldı. Poliklinik muayenesine gelen DM si olmayan, sağlıklı 50 hastanın 100 gözü kontrol grubu (grup 3) olarak seçildi. Tüm gruplara ayrıntılı oftalmolojik muayene yapıldı. Kornea patolojisi ve daha önceden geçirilmiş cerrahi öyküsü olan hastalar çalışma kapsamına alınmadı. Tüm hastaların SKK'sı topikal anestezi altında ultrasonik pakimetri cihazı (Optopol, Echoson Demsin M, Poland ) ile ölçüldü. Bulgular: DM'li hastaların ortalama santral kornea kalınlığı 548.94±37.13 µm; kontrol grubunun ortalama santral kornea kalınlığı 533.45±43.38 µm idi. Santral kornea kalınlığı DM'li hastalarda kontrol grubu ile karşılaştırıldığında istatistiksel olarak anlamlı derecede yüksek bulundu (p< 0.05). Diyabetik retinopatisi olan grubun (grup 1) santral kornea kalınlığı 558.39 ± 29.8 µm, diyabetik retinopatisi olmayan grubun (grup 2) santral kornea kalınlığı 543.14±40.1 µm idi. Bu iki gup arasında yapılan istatistiksel değerlendirmede diyabetik retinopatisi olan hastaların santral kornea kalınlığı retinopatisi olmayan hastalara göre anlamlı derecede yüksek bulundu (p

A pigmented optic nerve head lesion was detected on fundoscopy in a 57 years old female who presented with bad distance visual acuity. Based on clinical findings and ancillary studies, our diagnosis was (presumed) optic disc melanocytoma, and periodic examinations were scheduled. One year later the tumour size did not show any change. Patients with melanocytoma should be examined at regular intervals, serial fundus photographs are useful for monitoring growth and suspecting malignant transformation., Uzağı net görememe yakınması ile başvuran 57 yaşındaki kadın hastada optik sinir başında pigmente bir lezyon saptandı. Klinik bulgular ve tanıya yardımcı testler ile hastaya olası optik disk melanositomu ön tanısı kondu, periyodik kontrol muayeneleri planlandı. Bir yıllık izlem sonunda tümör büyüklüğünde değişiklik olmadı. Melanositoma tanısı düşünülen hastalar düzenli aralıklar ile takip edilmelidir. Periyodik izlem ve fundus fotoğrafları lezyon büyümesinin takibinde ve malign dönüşüm olasılığının belirlenmesinde önemlidir.

Periorbital necrotizing fasciitis is a soft tissue enfection, usually polymicrobial, characterised by necrosis of fascia and subcutaneous tissue. It frequently involves the groin, abdomen and extremities, but rarely involves the fascial region. In this article a case is presented of a 57-year-old woman who following a kick of cow developed a periorbital necrotising fasciitis. Bacteriological investigations revealed the presence of Streptococcus pyogenes. The virulence of this microorganism requires an aggressive approach to the patient with periorbital necrotizing fasciitis, which is refractory to intravenous antibiotics. Early treatment may limit extensive eyelid necrosis, the resultant secondary deformity, and the need for multiple reconstructive procedures., Nekrotizan fassiit, fasya ve cilt altı dokunun nekrozu ile karakterize, genellikle birden fazla mikroorganizmanın sebep olduğu bir yumuşak doku enfeksiyonudur. İnguinal bölge, karın ve ekstremitelerde sık görülmesine karşılık nadiren yüz bölgesinde de rastlanır. Bu çalışmada 57 yaşındaki bir kadın hastada inek tepmesinden sonra periorbital nekrotizan fassiit oluşumu sunulmuştur. Yapılan bakteriyolojik çalışmalarda streptococcus pyogenes izole edildi. İntravenöz antibiyotiklere dirençli olan periorbital nekrotizan fassiitli hastalarda bu mikroorganizmanın virülansı nedeniyle agressif yaklaşım gereklidir. Erken tedavi göz kapağındaki nekrozun artmasını, sekonder deformite oluşumunu ve birçok rekonstrüktif girişime olan ihtiyacı azaltır.

Aim: We evaluated the etiology, peroperative and postoperative complications of the cases who underwent pars plana vitrectomy in our clinic. Material and method: Twenty patients who were operated and followed between November 2001- November 2002 included in this study. Twenty eyes of 20 patients were included in this study. The mean age of the patients was 61 (3-76) years old, of them, 9 (45%) were male, and 11 (55%) were female. The mean follow up period was 6 months (range 1-11 months). Results: Diagnoses were vitreous hemorrhage in 12 (60%), endophtalmitis in 3 (15%), asteroid hyalozis in 1 (5%), dislocated intraocular lens in 1 (5%), nucleus drop in 3 (15%) patients. Peroperative complications were iatrogenic retinal tears in 2 (10%), nucleus drop in 1 (5%), minimal vitreous hemorrhage in 1 (5%), corneal epithelial defects in 3 (15%) patients. Postoperative complications were corneal edema in 5 (25%), fibrinous reaction in 4 (20%), hypotony in 3 (15%), increased intraocular pressure in 3 (15%), retinal detachment in 2 (10%), vitreous hemorrhage in 2 (10%) and cataract in 1 (5%) patients. Conclusion: Etiology, peroperative and postoperative complications of PPV are affects of operations. We consider that we will obtain more successful results when our surgical experiences are getting improve., Amaç: Kliniğimizde pars plana vitrektomi yapılan olguların etyolojileri, peroperatif ve postoperatif komplikasyonları değerlendirildi. Gereç ve yöntem: Kliniğimizde Kasım 2001-Kasım 2002 tarihleri arasında pars plana vitrektomi (PPV) uygulanan 20 olgunun 20 gözü çalışma kapsamına alınmıştır. Olguların yaş ortalaması 61±10.25 (3-76) olup, 9 (%45) olgu erkek, 11 (%55) olgu bayan hastalardan oluşmaktadır. Ortalama takip süresi 6± 2.8 (1-11) aydır. Bulgular: Ameliyat endikasyonu etyolojilerine göre 12 olguda (%60) vitreus hemorajisi, 3 olguda (%15) endoftalmitis, 1 olguda (%5) asteroid hyalozis, 1 olguda (%5) göz içi lens (GIL) dislokasyonu, 3 olguda (%15) vitreus içine nukleus düşmesi olarak saptandı. Ameliyat esnasında olguların 2 sinde (%10) iyatrojenik retina yırtığı, 1 olguda (%5) vitreus içine nukleus düşmesi, 2 olguda (%10) minimal vitreus hemorajisi ve 3 olguda (%15) ise kornea epitel defekti görülmüştür. Ameliyat sonrası 5 olguda (%25) kornea ödemi, 4 olguda (%20) fibrin reaksiyonu, 3 olguda (%15) göz içi basınç artışı, 3 olguda (%15) hipotoni, 2 olguda (%10) retina dekolmanı, 2 olguda (%10) vitreus hemorajisi ve 1 olguda (%5) ise katarakt görülmüştür. Sonuç: PPV ameliyatlarında başarıyı etyoloji, peroperatif ve postoperatif komplikasyonlar belirlemektedir. Cerrahi tecrübemiz geliştikçe başarı oranlarımızın artacağı kanaatindeyiz.

Aim: Penetrating keratoplasty was evaluated between July 1993 and July 2000 in our clinic. Material and Methods: 102 penetrating keratoplasty operations have been performed on 86 patients. The follow up periods of our cases were between five months and thirty-two months, the average follow up period was six-teen months. Results: The graft was clear in 90 (88.2%) eyes of 102 cases which were followed up between July 1993 and July 2000. Visual rehabilitation was obtained in 81 (79.4%) cases. Conclusion: Penetrating keratoplasty is a successful surgical technique with excellent long term results and relatively low complication rate., Amaç: Kliniğimizde Haziran 1993 – Haziran 2000 tarihleri arasında yapılan penetran keratoplasti ameliyatları değerlendirildi. Gereç ve Yöntem: Farklı tanılar ile 86 hastanın 102 gözüne penetran keratoplasti uygulanmıştır. Olgularımız en kısa 5 ay, en uzun 32 ay olmak üzere ortalama 16 ay takip edilmiştir. Bulgular: Haziran 1993 – Haziran 2000 tarihleri arasında takip edilen 102 olgunun 90' ında (%88.2) grefon şeffaf olarak bulunmuştur. 81 olguda (%79.4) görme keskinliğinde artma sağlanmıştır. Sonuç : Penetran keratoplasti, başarı oranı yüksek, iyi prognozlu ve komplikasyon oranları kabul edilebilir nitelikte bir cerrahi yöntemdir.

Aim: We report a case in which, although we planned to perform a penetrating keratoplasty for corneal opacity, the host's Descemet's membrane became inadvertently detached and the operation resulted with double anterior chamber., Amaç: Bu çalışmada, kornea opasitesi nedeni ile penetran keratoplasti uyguladığımız, ancak cerrahi sırasında hastanın kendi Desme'sinin dekole olması ile çift ön kamara oluşan bir olgu sunulmuştur.

Turk J Med Sci 2005; 35(1): 51-55. Full text: pdf Other articles published in the same issue: Turk J Med Sci,vol.35,iss.1.

Many chiral ligands bearing phosphorus donor atoms were developed and applied in the area of metal catalyzed asymmetric catalysis. A new chiral bis(phoshinite) ligand was successfully synthesized from optically active (1S,8S)-3,6-[N-(S)-alpha-phenylethyl] diaza-1,8-diphenoxymethyl-1,8-octanediol in high yield. A ruthenium(II) complex generated in situ from [Ru(eta(6)-p-cymene)(mu-Cl)Cl](2), bis(phosphinite) ligand and KOH acts as an active catalyst for asymmetric transfer hydrogenation (ATH) of acetophenone derivatives in isopropyl alcohol (IPA) as both solvent and hydrogen source. The catalytic reaction proceeds cleanly to give enantiomerically enriched secondary alcohols up to 90% or 89% ee's at 50 or 82 degrees C, respectively. (C) 2013 Elsevier B. V. All rights reserved.

This study represents a facile synthesis of building blocks (1–3) of crown ethers and amine precoursers (4a-d). The study also involves synthesis of mono and dibenzo N, N-disubstituted diaza 18-crown-6 derivatives with high yield without chromatographic purification and high vacuum distillation. The complex ability of host the ethers was evaluated in terms of structural modification.

The chiral monoaza-15-crown-5 ethers 4 and 5 were prepared from L-phenylalaninol and L-leucinol, respectively. The molecular recognition of these chiral crown ethers for L-amino acid ethyl esters was characterised by UV-visible spectroscopy. Binding constants ( Ka), free-energy changes (–Δ Go), enthalpy changes (Δ H) and entropy change (Δ S) values were determined for hosts 4 and 5 with L-amino acid ethyl ester hydrochlorides in CHCl3.

Ruthenium complexes (I) are readily prepared and their structures are supported by 1H and 13C NMR data.

Three aminophosphine complexes are prepared and their catalytic activity in the transfer hydrogenation of acetophenone derivatives is investigated.

Four novel C(2)-symmetric enantiomerically pure, chiral pyridine-18-crown-6 type macrocycles containing lipophilic chains at the stereogenic centers were prepared. The enantioselectivity of the new ligands toward the enantiomers of D-,L-amino acid methyl ester derivatives were also determined by (1)H NMR titration method. These novel macrocycles have been showed to be strong complexing agents for D- and L-amino acid methyl ester hydrochloride salts (with K(ass) up to 13590 M(-1) and Delta G(0) up to 23.3 kJ mol(-1) and selectivity ratio: 80:20) by (1)H NMR titration methods. These macrocyclic hosts exhibited enantioselective binding towards the D-enantiomer of valine methyl ester hydrochloride with K(D)/K(L), up to 5.08 in CDCl(3) with 0.25% CD(3)OD. (C) 2011 Elsevier Ltd. All rights reserved.

A series of new C 2 -symmetric chiral aza crown ether macrocycles 1 – 4 have been synthesized from ( S )-3-aryloxy-1,2-propanediol and ( S )-1,2-propanediol for the enantiomeric recognition of amino acid ester derivatives. These new macrocycles have been shown to be strong complexing agents for primary organic ammonium salts (with K up to 176.93 M −1 and Δ G ° up to 12.81 kJ mol −1 ) by 1 H NMR titration. These macrocyclic host exhibited enantioselective bonding toward the d -enantiomer of phenylalanine methyl ester hydrochloride with K D / K L up to 6.87 in CDCl 3 with 0.25% CD 3 OD.