Atroposelective PIII /PV =O Redox Catalysis for the Isoquinoline-Forming Staudinger-aza-Wittig Reaction

Herein, we describe the feasibility of atroposelective PIII /PV =O redox organocatalysis by the Staudinger-aza-Wittig reaction. The formation of isoquinoline heterocycles thereby enables the synthesis of a broad range of valuable atropisomers under mild conditions with enantioselectivities of up to 98 : 2 e.r. Readily prepared azido cinnamate substrates convert in high yield with stereocontrol by a chiral phosphine catalyst, which is regenerated using a silane reductant under Brønsted acid co-catalysis. The reaction provides access to diversified aryl isoquinolines, as well as benzoisoquinoline and naphthyridine atropisomers. The products are expeditiously transformed into N-oxides, naphthol and triaryl phosphine variants of prevalent catalysts and ligands. With dinitrogen release and aromatization as ideal driving forces, it is anticipated that atroposelective redox organocatalysis provides access to a multitude of aromatic heterocycles with precise control over their configuration.

Allylboronic Esters as Acceptors in Radical Addition, Boron 1,2-Migration, and Trapping Cascades

Radical 1,3-carboheteroarylation and 1,3-hydroalkylation of allylboronic esters comprising a 1,2-boron shift is reported. Allylboronic esters are generally used in synthesis as allylation reagents, where the boronic ester moiety gets lost. In the introduced cascades, alkylboronic esters are obtained with the boron entity remaining in the product. The carboheteroarylation of the allylboronic esters are conducted without a metal catalyst, and the 1,3-hydroalkylation is achieved using iron catalysis. Both reactions work efficiently under mild conditions.

Transition-Metal-Free Intramolecular Radical Aminoboration of Unactivated Alkenes

An efficient transition-metal-free cyclizing radical aminoboration of unactivated alkenes is reported. The B₂(OH)₄ reagent was used as the boron source, and the interaction between B₂(OH)₄ and an aryloxyamide N-radical precursor enabled the chain reaction to be initiated upon irradiation in the absence of any catalyst. This transformation proceeds via cyclization of an N-radical with subsequent intermolecular C-radical borylation. The cascade shows a broad scope and provides a wide range of high-value cyclic 1,2-aminoboronic esters.

Remote Radical Desaturation of Unactivated C-H Bonds in Amides

Desaturation of inert aliphatic C-H bonds in alkanes to form the corresponding alkenes is challenging. In this communication, a new and practical strategy for remote site-selective desaturation of amides via radical chemistry is reported. The readily installed N-allylsulfonylamide moiety serves as an N radical precursor. Intramolecular 1,5-hydrogen atom transfer from an inert C-H bond to the N-radical generates a translocated C-radical which is subsequently oxidized and deprotonated to give the corresponding alkene. The commercially available methanesulfonyl chloride is used as reagent and a Cu/Ag-couple as oxidant. The remote desaturation is realized on different types of unactivated sp³ -C-H bonds. The potential synthetic utility of this method is further demonstrated by the dehydrogenation of natural product derivatives and drugs.

Intramolecular Hydrogen Atom Transfer Induced 1,2-Migration of Boronate Complexes

Radical α-C-H functionalization of alk-5-enyl boronic esters with concomitant functionalization of the alkene moiety is reported. These cascades comprise perfluoroalkyl radical addition to the alkene moiety of a boronate complex, intramolecular hydrogen atom transfer (HAT), single electron oxidation, and 1,2-alkyl/aryl migration. The boronate complexes are readily generated in situ by reaction of the alkenyl boronic esters with alkyl or aryl lithium reagents. Products are formed in a divergent approach by varying carbon radical precursors as well as alkyl/aryl lithium donors, and reactions proceed under mild conditions upon UV irradiation.

Preparation of α-Perfluoroalkyl Ketones from α,β-Unsaturated Ketones via Formal Hydroperfluoroalkylation

Formal hydroperfluoroalkylation of enones is achieved in a two-step process comprising conjugate hydroboration and subsequent radical perfluoroalkylation. The 1,4-hydroboration of the enone is conducted in the absence of any transition metal catalyst with catecholborane in 1,2-dichloroethane, and the generated boron enolate is in situ α-perfluoroalkylated with a perfluoroalkyl iodide upon blue LED irradiation in the presence of an amine additive. Both reactions proceed under very mild conditions at room temperature.

Outcomes of surgery for post-cholecystectomy bile duct injuries: An audit from a tertiary referral center

AIM OF THE STUDY

Bile duct injury (BDI) after cholecystectomy is a serious complication. It often requires surgical repair. The aim of this study was to report on the short and long-term outcomes of surgery for post-cholecystectomy BDI.

PATIENTS AND METHODS

All the patients, who underwent surgery for post-cholecystectomy BDI between August 2007 and September 2017, were retrospectively reviewed. McDonald grading system was used to assess the long-term outcome. The risk factors for unsatisfactory long-term outcome were analyzed by univariate and multivatiate logistic regression analysis.

RESULTS

In total, 228 patients had a Roux-en-Y hepaticojejunostomy. Open cholecystectomy was the major cause of BDI (61%). The median time from injury to definitive repair was 6 months. The types of BDI were as follows: E1 in 13 (5.7%), E2 in 68 (29.82%), E3 in 108 (47.36%), E4 in 28 (12.28%), and E5 in 11 (4.82%) patients respectively. Postoperative morbidity and mortality were 25% and 1.31% respectively. After a median follow-up of 58 months, 90% patients had excellent to good outcome. Recurrent stricture developed in 6 (3%) patients. On multivariate analysis, long injury-repair interval and previous attempt at repair were independent predictors for unsatisfactory long-term outcome.

CONCLUSION

Surgical reconstruction affords excellent to good results for majority of the patients with post-cholecystectomy BDI. As longer delay in definitive repair and previous attempt at repair were associated with unsatisfactory long-term outcome, early referral to a specialized hepatobiliary surgery unit is recommended.

Cobalt complex catalyzed atom-economical synthesis of quinoxaline, quinoline and 2-alkylaminoquinoline derivatives

A new phosphine-free Co(ii) complex-catalyzed synthesis of various quinoxalines via dehydrogenative coupling of vicinal diols with both o-phenylenediamines and 2-nitroanilines is reported. This complex was also effective for the synthesis of quinolines. The practical aspect of this catalytic system was revealed by the one-pot synthesis of 2-alkylaminoquinolines.

Growth, yield, water use efficiency and competitive functions of intercropping system of maize (Zea mays L.) and mungbean (Vigna radiata L.) as influenced by irrigation

Field experiment was conducted at Instructional Farm, Jaguli (Mohanpur), Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India during two consecutive summer seasons of 2010-11, and 2011-12. The experiment was laid out in split-plot design having 4 levels of irrigation– rainfed without mulch, rainfed with mulch, irrigation at IW (depth of irrigation water) / CPE (Cumulative pan evaporation) ratios of 0.5 and 0.75 in main-plot and 4 inter cropping systems, sole maize, sole mungbean, maize + mungbean (1:1 row ratio) and maize + mungbean (3:2 row ratio) considered as sub-plot treatments replicated thrice. Results revealed that application of irrigation and intercropping systems markedly influenced the growth, yield and yield components (number of cobs/plant, number of grains/cob in case of maize and number of pods/plant and number of seeds/pod in case of mungbean) where the maximum value of these components were recorded with the application of irrigation at IW/CPE ratio 0.75 in sole crop. Maize-mungbean in 3:2 row ratio yielded higher than that of 1:1 intercropping system which might be due to less light interception and more competition for water and nutrition between both the crops. CU of water increased with the increasing levels of irrigation and the maximum value (17.75 kg ha-1 mm- 1) of WUE (water use efficiency) was observed with irrigation at IW: CPE ratio 0.75 under intercropping system of maize : mungbean in 3:2 row ratio followed by IW: CPE ratio 0.50. Among the sole crop, maximum WUE was with IW/CPE ratio 0.75 might be due to more consumption of water corresponding to production potential of maize, while, it was more under rainfed with mulch in mungbean. The relative crowding coefficient (RCC) also revealed both the intercropping systems were advantageous and the land equivalent ratio (LER) increased with the level of irrigation.Thus, maize grown in association with mungbean (3:2 row ratio) were found to be more profitable (B:C ratio of 2.58) with higher monetary advantage as compared to sole crop of maize (B:C ratio of 1.98) with the application of irrigation at IW: CPE ratio of 0.75 in new alluvial zone of West Bengal.SAARC J. Agri., 13(2): 94-107 (2015)

Corrective role of Eugenia jambolana on testicular impairment in streptozotocin-induced diabetic male albino rat: an approach through genomic and proteomic study

The present study was conducted to explore the effect of ethyl acetate fraction of hydro-methanolic (40 : 60) extract of seed of Eugenia jambolana on testicular impairment in diabetic rats. In this respect, biomarkers of oxidative stress, genomics and proteomics in testicular tissue were assessed. Side by side, glycated haemoglobin, serum testosterone, activities of glutamate oxaloacetate transaminase and glutamate pyruvate transaminase in serum, epididymal sperm count including reproductive organosomatic indices were evaluated. Results indicate that a significant recovery (P < 0.05) in the levels of these parameters in fraction-treated diabetic group in comparison with diabetic control. A significant recovery was noted (P < 0.05) in the expression of Bax and Bcl-2 gene towards the control after the treatment of said fraction. Histological study also focused a significant recovery (P < 0.05) in the number of different generation of germ cells at stage VII of spermatogenesis in fraction-treated diabetic group. The said fraction treatment to diabetic rat can recover the activities of serum glutamate oxaloacetate transaminase and glutamate pyruvate transaminase significantly towards the control (P < 0.05). Finally, it may be concluded that ethyl acetate fraction of seed of E. jambolana has a promiseable remedial effect on diabetes-induced testicular dysfunctions in male rat without inducing any metabolic toxicity.

Effect of different intensities of swimming exercise on testicular oxidative stress and reproductive dysfunction in mature male albino Wistar rats

Swimming exercise for 1, 2 and 3 hr for 5 days/week for consecutive 4 weeks, results in a significant reduction in testicular, epididymal, prostetic, seminal vesicle somatic indices; epididymal sperm count, sperm motility; preleptotine spermatocytes, mid pachytene spermatocytes and stage 7 spermatids; plasma levels of testosterone, luteinizing hormone; testicular delta5, 3beta-hydroxysteroid dehydrogenase, 17beta-hydroxysteroid dehydrogenase; testicular superoxide dismutase, catalase, glutathione peroxidase, glutathione-s-transferase and glutathione along with significant elevation in malondialdehyde in male albino rats. However, no significant change was noted in final body weight, spermatogonia-A and plasma level of follicle stimulating hormone. The results that oxidative stress develops with the increasing of exercise intensity, which may interfere in male reproductive activities.

Effect of intensive exercise-induced testicular gametogenic and steroidogenic disorders in mature male Wistar strain rats: a correlative approach to oxidative stress

AIMS

In order to investigate the effects of intensive exercise on reproductive dysfunctions in relation to oxidative stress, a total of 12 male rats (age: 3 months, weight: 127 +/- 2.86 g) were randomly divided into: (1) control group (CG, n = 6) and (2) experimental group (Exp. G, n = 6).

METHODS

An exercise protocol of 3 h swimming day(-1), 5 days week(-1) was followed for 4 weeks in Exp. G, with no exercise in CG. All the animals were killed; blood, testes and the accessory sex organs were collected for estimation of different parameters.

RESULTS

A significant diminution (P < 0.001) was noted in testicular Delta5, 3beta-hydroxy-steroid dehydrogenase (Delta5, 3beta-HSD), 17beta-hydroxy steroid dehydrogenase (17beta-HSD); plasma levels of testosterone, luteinizing hormone (LH); preleptotine spermatocytes (pLSc), midpachytene spermatocytes (mPSc) and stage 7 spermatids (7Sd); with no significant alteration in follicle stimulating hormone (FSH) and spermatogoia A (Asg) after intensive exercise. A significant elevation (P < 0.001) in malondialdehyde (MDA) and conjugated dienes (CD) along with significant reduction (P < 0.001) in glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferase (GST) and peroxidase were found in testes of Exp. G. Moreover, the somatic index of testes and accessory sex organs were also decreased significantly (P < 0.001) after exercise. High correlations have been found in 17 beta-HSD with CAT (r = 0.90, P < 0.05) and peroxidase (r = 0.83, P < 0.05), epididymal somatic index with CD (r = -0.91; P < 0.05) and GSH (r = 0.84, P < 0.05).

CONCLUSION

The present study focused an chronic intensive exercise-induced oxidative stress that may cause dysfunctions in male reproductive system including steroidogenesis and spermatogenesis.

Dose-dependent response to an intratesticular injection of calcium chloride for induction of chemosterilization in adult albino rats

This study concerned the minimum and optimum effective doses of calcium chloride needed for induction of chemosterilization in male albino rats, 30 days after a single intratesticular injection of calcium chloride (CaCl2.2H2O) solution at 2.5, 5, 10 or 20 mg per 100 g body weight per testis. There was a significant diminution in the relative wet weight of the sex organs (p<0.01), epididymal sperm count (p<0.001), plasma concentration of testosterone (p<0.01), testicular activities of delta5,3beta-hydroxy steroid dehydrogenase (delta5,3beta-HSD), 17beta-hydroxy steroid dehydrogenase (17beta-HSD) (p<0.01), glutathione S-transferase (GST) (p<0.01), superoxide dismutase (SOD) (p<0.01), and peroxidase (p<0.01), significant elevations in testicular content of malondialdehyde (MDA) and conjugated dienes (p<0.01), along with derangement of seminiferous tubular architecture and degeneration of the Leydig cells in the testis and elevations in the concentrations in the plasma of LH and FSH (p<0.01), commencing at a dose of 5 mg, with the greatest effects at a dose of 20 mg. No significant alterations in these factors occurred at the dose of 2.5 mg in comparison to the control that received only the vehicle. There was no significant alteration in the plasma concentrations of prolactin (p>0.05), corticosterone (p>0.05) or fasting blood glucose or in the rectal temperature (p>0.05) at any of the doses relative to the control group, suggesting that this chemosterilizing procedure did not exert any chronic stress on the experimental animals. From these observations, it may be suggested that 5 mg should be considered as the minimum dose, and 10 mg or 20 mg as the optimum dose, whereas 2.5 mg was ineffective for induction of chemosterilization. There would seem to be little point in using more than 20 mg of calcium chloride for this purpose. Intratesticular injection of calcium chloride at an effective dose may be considered as an alternative to surgical castration.