Mini-Reviews in Organic Chemistry - Volume 10, Issue 1, 2013

Azaheterocycles comprise relevant target structures within organic chemistry due to the broad diversity of biological activities associated with these scaffolds. In this review, the most important recent procedures for the preparation of functionalized six-membered azaheterocyclic compounds by ring transformation of β-lactams are summarized and discussed.

The research on medicinal plants is gaining popularity due to their high efficacy, safety, quality and low side effects in comparison of synthetic medicines. Phoebe plants have been used in traditional medicine for curing various diseases worldwide. The Genus Phoebe comprises of about 200 species, distributed in Indo-Malaysia, West Europe, Tropical America and India. The phytochemical studies on the Genus Phoebe have revealed the presence of mostly alkaloids along with terpenoids, flavonoids, lignans and steroids. The members of this genus showed various activities such as antitumor, antiplasmodial, antimicrobial, antifungal, antidiabetic, muscles relaxant etc. The aim of present review is to explore the up to date knowledge concerning ethnobotany, pharmacology and phytochemistry of the Genus Phoebe.

The advances in the chemistry of Mannich bases of electron-rich, monocyclic five-membered heterocycles with one heteroatom thiophene and furan are reviewed. The aminomethylation of these heterocycles along with the reactivity and the applications of their Mannich bases are summarized.

There has been considerable interest in the development of novel heterocyclic compounds with varied biological activities. Triazoles are a special class of heterocyclic compounds with a broad spectrum of biological activities such as antimicrobial, cytotoxic, antihistaminic, anticonvulsant, analgesic, anti-inflammatory, insecticidal, antimycotic, antimycobacterial, anticancer, antiprotozoal, antimalarial and anti-ulcer activity. Therefore, many researchers have synthesized these compounds as target structures and evaluated their biological activities. These observations help the researchers for the development of new triazole compounds with enhanced biological activities. This review focuses on the various synthetic strategies followed for the synthesis of triazoles, and their biological activities.

Thiazolidines (TZDs) or glitazones are one of the important classes of insulin sensitizers used in the management of type 2 diabetes mellitus. These agents, however, suffer from some serious side effects such as fluid retention, weight gain, congestive heart failure, bone fracture and possibly bladder cancer, which resulted in their withdrawal from clinical use. The TZDs that were withdrawn from the clinical use were developed at the time when enough scientific data were not available on the structure and the transcriptional mechanisms of peroxisome proliferator activated receptors (PPARs). Recent advances in understanding the structure and function of PPARs, however, has led to more rationalized approaches to develop these agents. The present review discusses the various approaches that have been made to develop newer glitazones devoid of the problems associated with current TZDs. These approaches are based on the structural considerations of both the ligands and the receptors and also on the profile alterations of the ligands.

Chalcones are the main precursors for the biosynthesis of flavonoids and isoflavonoids. Chalcones comprise of a three carbon α, β-unsaturated carbonyl system. These are the condensation products of aromatic aldehyde with acetophenones in the presence of catalyst. They go through a variety of chemical reactions and are found beneficial in synthesis of pyrazoline, isoxazole and an assortment of heterocyclic compounds. Chalcones play pivotal role in synthesizing a range of remedial compounds. They have exhibited impressive curative efficacy for the treatment of numerous diseases. Chalcone based derivatives have gained focus since they possess simple structures and sundry pharmacological actions. A number of techniques and schemes have been reported for the synthesis of these compounds. Amongst all the stated methods, Aldol condensation and Claisen-Schmidt condensation still hold high position. Other renowned techniques include Suzuki reaction, Witting reaction, Friedel-Crafts acylation with cinnamoyl chloride, Photo-Fries rearrangement of phenyl cinnamates etc. These innovative techniques employ various catalysts and reagents including SOCl2 natural phosphate, lithium nitrate, amino grafted zeolites, zinc oxide, water, Na2CO3, PEG400, silicasulfuric acid, ZrCl4 and ionic liquid etc. The development of improved strategies for the synthesis of α, β- unsaturated carbonyl compounds is still in demand. Briefly, we have explained the methods and catalysts used in the synthesis of chalcones in a review form to provide information for the development of new-fangled processes aiming better yield, less reaction time and minimum side effects.

Stannous chloride, an inexpensive mild Lewis acid has been used in various organic synthetic operations. It was used in reducing various functional groups in the earlier days. The recent trends however expanded the scope of its applications in organic synthesis using it as an efficient catalyst. This review highlights the catalytic potential of this reagent in a wide range of reactions such as allylation, propargylation, multicomponent reactions and syntheses of bioactive heterocycles.

Due to the extensive application of porphyrins today, this paper aims to present a short review on the synthesis of the first and principal methodologies and compares their yields and reaction conditions. It should be noted that these methodologies were the precursors to the development of numerous syntheses of porphyrins.