Application of N-heterocyclic carbene-Cu(I) complexes as catalysts in organic synthesis: a review.

N-Heterocyclic carbenes (NHCs) are a special type of carbenes in which the carbene carbon atom is part of the nitrogen heterocyclic ring. Due to the simplicity of their synthesis and the modularity of their stereoelectronic properties, NHCs have unquestionably emerged as one of the most fascinating and well-known species in chemical science. The remarkable stability of NHCs can be attributed to both kinetic as well as thermodynamic effects caused by its structural features. NHCs constitute a well-established class of new ligands in organometallic chemistry. Although initially NHCs were regarded as pure σ-donor ligands, later experimental and theoretical studies established the presence of a significant back donation from the d-orbital of the metal to the π* orbital of the NHC. Over the last two decades, NHC-metal complexes have been extensively used as efficient catalysts in different types of organic reactions. Of these, NHC-Cu(I) complexes found prominence for various reasons, such as ease of preparation, possibility of structural diversity, low cost, and versatile applications. This article overviews applications of NHC-Cu(I) complexes as catalysts in organic synthesis over the last 12 years, which include hydrosilylation reactions, conjugate addition, [3 + 2] cycloaddition, A3 reaction, boration and hydroboration, N-H and C(sp2)-H carboxylation, C(sp2)-H alkenylation and allylation, C(sp2)-H arylation, C(sp2)-H amidation, and C(sp2)-H thiolation. Preceding the section of applications, a brief description of the structure of NHCs, nature of NHC-metal bond, and methods of preparation of NHC-Cu complexes is provided.

Dienophilic reactivity of 2-phosphaindolizines: a conceptual DFT investigation.

The >C=P- or -N=P- functionality in 1,3-azaphospholo[1,5-a]pyridine, named as 2-phosphaindolizine and its 1- and 3-aza derivatives act as dienophiles and undergo Diels-Alder reactions with 1,3-dienes. However, the dienophilic reactivity is affected by the nature of the substituent groups on the two sides of the σ2,λ3-P atom and also by the presence of more nitrogen atom(s) in the five-membered ring. The conceptual density functional theory (DFT) calculations have been used in recent years to predict the reactivity of organic molecules in reactions. We calculated global hardness (η), global softness (S), electronic chemical potential (µ), electrophilicity (ω), and nucleophilicity (N) indices of four classes of 2-phosphaindolizines, on the basis of which their observed relative dienophilic reactivities could be rationalized. Besides, the Fukui functions of the carbon/nitrogen and phosphorus atoms of the >C=P- and -N=P- functionalities were also computed which revealed their hard electrophilic character and accorded well with the dienophilic reactivities observed experimentally. Furthermore, energies and symmetries of the lowest unoccupied molecular orbitals (LUMO) of 2-phosphaindolizines were found to be in conformity with their dienophilic reactivities.

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides.

Nitrogen-containing scaffolds are ubiquitous in nature and constitute an important class of building blocks in organic synthesis. The asymmetric aza-Michael reaction (aza-MR) alone or in tandem with other organic reaction(s) is an important synthetic tool to form new C-N bond(s) leading to developing new libraries of diverse types of bioactive nitrogen compounds. The synthesis and application of a variety of organocatalysts for accomplishing highly useful organic syntheses without causing environmental pollution in compliance with 'Green Chemistry" has been a landmark development in the recent past. Application of many of these organocatalysts has been extended to asymmetric aza-MR during the last two decades. The present article overviews the literature published during the last 10 years concerning the asymmetric aza-MR of amines and amides catalysed by organocatalysts. Both types of the organocatalysts, i.e., those acting through non-covalent interactions and those working through covalent bond formation have been applied for the asymmetric aza-MR. Thus, the review includes the examples wherein cinchona alkaloids, squaramides, chiral amines, phase-transfer catalysts and chiral bifunctional thioureas have been used, which activate the substrates through hydrogen bond formation. Most of these reactions are accompanied by high yields and enantiomeric excesses. On the other hand, N-heterocyclic carbenes and chiral pyrrolidine derivatives acting through covalent bond formation such as the iminium ions with the substrates have also been included. Wherever possible, a comparison has been made between the efficacies of various organocatalysts in asymmetric aza-MR.

Cross-sectional study to assess the need to commence opportunistic screening of women for cervical cancer presenting with sexually transmitted disease in Western India.

This study examines the prevalence of suspected cervical cancer (established through the use of visual inspection with Lugol's Iodine - VILI) among outpatients attending Surat Municipal Institute of Medical Education & Research Hospital, India. A cross-sectional study was conducted on 356 patients; 178 with an established sexually transmitted disease (STD) and 178 patients without. Patients with positive results were investigated with cervical biopsy; out of 356 patients, 21.91% patients with STD and 12.35% patients without STD tested positive for VILI respectively (p = .017). The factors found to be significantly associated with a positive VILI test were STD, marital status, oral contraceptive pill use, a complaint of PV bleeding, white discharge on speculum examination (PS) and cervical erosion on PS. On applying multiple logistic regression, STD, age of patient in years, parity, OC pill use, a complaint of PV bleeding and cervical erosion on PS were found to be significant predictors of VILI positivity among the patients. STD patients are 2.5 times more likely to test positive for VILI than patients without STD. In Indian populations comparable to ours, opportunistic screening should be considered in gynaecology outpatient clinics for women presenting with complaints related to STDs.

Asymmetric Diels-Alder reaction with >C=P- functionality of the 2-phosphaindolizine-η(1)-P-aluminium(O-menthoxy) dichloride complex: experimental and theoretical results.

The Diels-Alder reaction of the 2-phosphaindolizine-η(1)-P-aluminium(O-menthoxy) dichloride complex with dimethylbutadiene was investigated experimentally and computationally. The >C=P- functionality of the complex reacts with 2,3-dimethylbutadiene with complete diastereoselectivity to afford [2 + 4] cycloadducts. Calculation of the model substrate, 3-methoxycarbonyl-1-methyl-2-phosphaindolizine-P-aluminium(O-menthoxy) dichloride (7a), at the DFT (B3LYP/6-31+G*) level reveals that the O-menthoxy moiety blocks the Re face of the >C=P- functionality, due to which the activation barrier of the Diels-Alder reaction of 7a with 1,3-butadiene, involving its attack from the Si face, is lower. It is found that in this case, the exo approach of the diene is slightly preferred over the endo approach.

Vaccine Wastage Assessment After Introduction of Open Vial Policy in Surat Municipal Corporation Area of India.

BACKGROUND: As per the vaccine management policy of the Government of India all vaccine vials opened for an immunization session were discarded at the end of that session, irrespective of the type of vaccine or the number of doses remaining in the vial prior to 2013. Subsequently, open vial policy (OVP) was introduced in 2013 and should reduce both vaccine wastage as well as governmental healthcare costs for immunization. This study evaluates the vaccine wastage after introduction of the OVP and its comparison with the previous study of vaccine wastage in Surat city before implementation of OVP. It needs to mention that the vaccine policy for this period under comparison was uniform except for the OVP. METHODS: Information regarding vaccine doses consumed and children vaccinated during immunization sessions of 24 urban health centers (UHCs) of Surat city were retrieved for the period of January 1st, 2014 to March 31st, 2014. The data were analyzed to estimate vaccine wastage rate (WR) and vaccine wastage factor (WF). In order to assess the impact of OVP, vaccine WR of this study was compared with that of previous study conducted in Surat city during January 1st, 2012 to March 31st, 2012. RESULTS: The vaccine WR for oral polio vaccine (OPV) has decreased from 25% to 13.62%, while the WRs for DPT, hepatitis B virus (HBV) and the pentavalent vaccine combinedly have decreased from 17.94% to 8.05%. Thus, by implementation of OVP, an estimated 747 727 doses of OPV and 343 725 doses of diphtheria, pertussis and tetanus toxoid vaccine (DPT), HBV and the pentavalent vaccines combinedly have been saved in Surat city of India in a year. CONCLUSION: The implementation of the OVP in Surat city has led to a significant lowering in the vaccine wastage, leading to savings due to lower vaccine requirements.

Cross-sectional study on socio-demographic and clinical correlates of depression among human immunodeficiency virus-positive patients in Surat City, Western India.

INTRODUCTION: Surat has the highest incidence of human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) in Gujarat, the main reason being its large migrant population. Mental health in HIV/AIDS has most often been a topic of neglect all over the world. This study attempts to assess the magnitude of depression and the socio-demographic and clinical variables associated with it in HIV-positive patients. METHODS: A cross-sectional study was conducted in 270 HIV-positive patients using Beck Depression Inventory (BDI; translated and validated in Gujarati and Hindi) along with a questionnaire for eliciting information on socio-demographic and clinical variables. RESULTS: The prevalence of depression among HIV-positive patients was 30% with 12.22% having mild depression; 14.07% with moderate depression and 3.7% with severe depression. Bivariate analysis showed that physical pain, physical illness, Cluster of Differentiation 4 (CD4)<300 cells/mm3, HIV positive spouse, discrimination at hospital, discrimination in society, government setup as the first place of HIV test and broken relationship with spouse after HIV disclosure were significantly associated with depression among the patients. On multiple logistic regression, discrimination at hospital, physical pain and CD4<300 cells/mm3 were found to be the significant predictors of depression among the patients. DISCUSSION: HIV-positive patients can be screened by counselors using easy-to-administer scales like BDI, which can be translated and validated into any regional language. A trained psychiatrist should be appointed at the Anti-Retroviral Therapy (ART) center to take care of the mental health issues of the patients.