Current Catalysis - Volume 4, Issue 3, 2015

Allyl alcohol has become an attractive feedstock for commercial organic synthesis after the development and technical-scale implementation of cost-effective methods for its manufacturing. Its major applications include hydroformylation to obtain C4 aldehyde alcohols in the presence of catalytic rhodium complexes, followed by their hydrogenation to 1,4-butanediol as the principal product. The development of phosphine ligands that are used in the hydroformylation reaction and commercial processes to obtain 1,4-butanediol from allyl alcohol are discussed.

In vivo, cytochrome P450 (P450) enzymes facilitate the majority of phase I metabolism of pharmaceuticals, making the identification and role of any contributing isozyme from this family a focal point in clinical trials for new chemical entities. In vitro models, traditionally used to examine metabolism, present several issues, as biological systems are inherently difficult. Interest in systems capable of replicating enzymes synthetically is growing; the structural and mechanistic similarities between synthetic metalloporphyrins and the heme-cofactor of oxygenase enzymes, particularly those in the P450 super-family, have led many researchers to investigate replicating the in vivo function of these enzymes using metalloporphyrin catalysts (MPCs). MPC systems are generally used concomitantly with alternative methods, or complimentarily when considered necessary for a targeted purpose. Progression in the area of biomimetic oxidations by synthetic MPCs has been hindered by two factors: inadequate knowledge of physiological enzyme function, and the inordinate amount of reaction variables that require optimization. This review serves to highlight recent work with small building-block molecules in the biomimetic field, and focuses on the role of each reaction variable when functioning as individual entities and/or units, in order to establish the best reagents and conditions to combine for an effective biomimetic system.

An efficient and environmentally benign diversity oriented synthetic protocol has been presented for the synthesis of structurally diverse spiroquinazolines. The hybrid druglike molecules incorporating medicinally privileged heterocyclic systems (spiroquinazolinespirooxindoles) have been synthesized by three-component reaction of isatoic anhydride, aromatic amines and substituted isatins using gluconic acid aqueous solution (GAAS, 50%, wt%) as an efficient, inexpensive and eco-friendly bio-based catalytic solvent system.

Gold nanoparticles, being highly recyclable and benign in nature, are nowadays emerging as an attractive choice in various catalytic reactions. Fluoride free coupling of organosilane reagents with aryl halides is an environment-friendly protocol for the formation of C-C bond. Here, we present the coupling of phenyltrimethoxysilane with various aryl halides in ethanol/water mixture, catalyzed by gold nanoparticles under microwave heating. The effect of various parameters, such as catalyst concentration, base, time, temperature etc. on the reaction was investigated. Excellent activity of catalyst is indicated in terms of TON (1,666) and TOF (10,036 h-1). This new result will undoubtedly expand the application of gold nanoparticles in organic catalytic reactions.