Current Organocatalysis (v.2, #1)
Current Organocatalysis-2014: An Overview by Bimal K. Banik (1-1).
Conjugated Diyne Chemistry: Synthesis, Natural Existence and Applications by Wei Shi (2-13).
1, 3-butadiynes, also known as the conjugated diynes, are important structures with rigid full-carbon sketch, and they have been found to exist widely in nature from the marine organisms to the interstellar space. Besides the special physiological activities, diynes have also been found to be crucial in material science. This review will focus on the synthesis of diynes, and more importantly, their existence and bioactivities, as well as their applications and further developing trends.
Dearomatization Strategies of Heteroaromatic Compounds by Gunasekar Ramachandran, Kulathu Iyer Sathiyanarayanan (14-26).
Dearomatization strategies of heteroaromatic compounds such as benzofurans, indoles, thiophenes, pyridines, and other heteroaromatic compounds afford the most efficient protocol for the synthesis of highly bioactive molecules, natural products and commercially available drugs. The use of these strategies has been significantly increased, which has fascinated several research groups as the dearomatization strategies of heteroaromatic compounds at C-2 & C-3 substitution leads to formation of numerous drug-like molecules. The recent developments in dearomatization strategies involving at C-2 & C-3 positions of various heteroaromatic compounds is discussed in this review.
The Effect of Lewis Acid Catalysis and Steric Effects on Reactions of Tin Hydrides by Wojciech J. Kinart, Cezary M. Kinart, Marcin Sendecki (27-36).
The catalytic influence of inorganic salts, polarity of solvent and addition of chosen additivities on free radical reactions of tin hydrides has been reviewed. There have been collected examples of different reactions as hydrostannation of alkynes with mixed tin hydrides as well as enantioselective reductions of derivatives of 2-bromo-2-arylpropionates, α-iodocoumarin and acetophenone with tin hydrides. For all of them the steric effect may be improved by the addition of inorganic salts. They have been discussed examples of tandem radical macrocyclisations and reactions of -amide radicals depending on polarity of solvent. They have been also presented examples of hydrostannation of methylenecycloprpanes effected by the addition of additivities.
Diversity Oriented p-TSA Catalyzed Efficient and Environmentally Benign Synthetic Protocol for the Synthesis of Structurally Diverse Heteroannulated Benzothiazolopyrimidines by Sarita Khandelwal, Anshu Rajawat, Yogesh Kumar Tailor, Mahendra Kumar (37-43).
Diversity oriented synthetic protocol has been presented for the synthesis of structurally diverse drug -like small molecules. The present method involves three-component domino reaction of 2- aminobenzothiazoles, thiophene-2-carbaldehyde and carbonyl compounds in the presence of a catalytic amount of p-toluenesulphonic acid (p-TSA) as a recyclable and reusable eco-friendly acid catalyst in aqueous- alcoholic medium (C2H5OH- H2O:v:v/ 1:5). The synthesis of structurally diverse heterocycles in very high yields (92-97%) from easily available starting materials, operational simplicity, mild reaction conditions, use of nontoxic and reusable acid catalyst, environmentally benign solvent system and shorter reaction time (10- 48 min) at comparatively low temperature are special features of the present synthetic protocol.
L-Arginine Catalysed Knoevenagel Condensation: An Unambiguous Synthesis of Cyano-Nitrophenylacetamide, Benzimidazole Acetonitrile & 3-Indole Substituted Alkenes by K. Srinivas, Naresh Kumar Katari, P. Satya Karuna, M.S. Surendra Babu (44-50).
L-Arginine catalyzed Knoevenagel condensation of active methylene compounds, 2-cyano-N-(2- nitrophenyl)acetamide, 2-cyanomethyl benzimidazole, ethylcyanoacetate with benzaldehydes, indole-3- carboxaldehydes under mild and efficient conditions resulting in the formation of respective products. The isolation procedure is quiet easy and products recovered without further purification.
Nanoporous Montmorillonite Catalyzed Condensation Reactions under Microwave Irradiation: A Green Approach by S. Ramesh, B.S. Jai Prakash, Y.S. Bhat (51-57).
Acid treatment of montmorillonite enhanced the acidity and also nanoporosity of the virgin clay. Montmorillonite clay was treated with p-TSA and HCl under microwave irradiation (MWI) and modified materials were characterized by BET, TPD-NH3 and FT-IR techniques. The activities of clays were studied for important condensation reactions such as the crossed aldol condensation and amide synthesis without solvent under MWI. Under conventional heating, maximum conversion was observed in 300 minutes while the same conversion was achieved in just 30 minutes under MWI. The activities of p-TSA treated clay were compared with HCl treated clays. The p-TSA treated clay showed surprisingly higher activity compared to other catalysts. The activity was attributed to the dealumination of structural Al and its migration to the interlayer region of the clay. The removal of Al made the material more nanoporous due to which accessibility to the acidic sites was better than the unmodified clay. Enhanced activity was due to higher amounts of interlayer aluminium in the p-TSA treated compared to HCl-treated ones. p-TSA treated clays retained their activity even after three subsequent runs in both the modes of heating. The catalyst used in the reaction rejuvenated by a simple procedure could be used for catalyzing the reaction again.
Chiral Bifunctional Ferrocenylphosphines as New Catalysts for aza- Morita-Baylis-Hillman Reactions of N-Sulfonated Imines with Methyl Vinyl Ketone by Haiwen Hu, Qian Tang, Aiping Tu, Weihui Zhong (58-63).
A series of new chiral bifunctional Ferrocenylphosphines was designed, synthesized and applied for the asymmetric aza-Morita-Baylis-Hillman reaction of N-sulfonated imines with methyl vinyl ketone (MVK). The reaction proceeded under mild conditions to afford the desired aza-MBH adducts in moderate to high yields with up to 56% ee value.
Construction of a Soluble Supramolecular Glutathione Peroxidase Mimic based on Host-Guest Interaction by Yanzhen Yin, Shufei Jiao, Ruirui Zhang, Xueqian Wang, Li Zhang, Lan Yang (64-70).
A soluble glutathione peroxidase mimic with the optimum structure (NCD-Te-NCD2.2) was constructed based on the supramolecular host-guest interaction. The self-assembled structure and catalytic mechanism of NCD-Te-NCD2.2 were detailed investigation. It was proved that NCD-Te-NCD2.2 could form the hollow vesicle-like aggregates in water. And saturation kinetics measurement indicated that NCD-Te- NCD2.2 exhibited the typical enzyme catalytic behavior. Furthermore, benefited from the hydrophobic microenvironment in vesicle-like aggregates, NCD-Te-NCD2.2 exhibited the specific recognition ability for hydrophobic substrates, which was one of the important characteristics of native glutathione peroxidase. The successful construction of NCD-Te-NCD2.2 not only provides an efficient preparation method for soluble GPx mimic but also highlights for construction of other giant supramolecular biomimetic enzymes.
Low Catalyst Loading, Highly Efficient D-glucosamine-derived Organocatalysts for Asymmetric Aldol Reactions by Hanxiao Liao, Chao Shen, Fangyi Shen, Pengfei Zhang, Weike Su (71-76).
Glucosamine as a kind of important nature chiral scaffold is widely regarded for its obvious advantages such as cheap, stable and readily available. In this communication, we reported the introduction of L-proline group at the amino functional group of D-glucosamine resulted in several efficient prolinamide organocatalysts, which could efficiently catalyze the asymmetric aldol reaction between acetone and various substituted benzaldehydes in the neat condition. Under the optimized conditions, 0.5 mol% of organocatalyst gave excellent chiral selectivity (83% ee value) with 88% yield, which was higher than that obtained using 10 mol% of organocatalyst.