Synthesis biologically active molecules

A number of groups have investigated the Pd-catalyzed amination of aromatic electrophiles for a particular application or synthetic problem. These synthetic applications can be divided loosely into four categories synthesis of biologically active molecules, synthesis of materials for electronics or ion binding, amination in solid-phase organic synthesis, and synthesis of new ligands for transition metals. 

I 7 Synthetic Applications of Aminotran erases for the Preparation of Biologically Active Molecules Synthesis mode... 

An important consideration for all radiopharmaceuticals and especially radiolabeled biologically active molecules is specific activity. There are two types of specific activity radionucHdic and biological. RadionucHdic specific activity refers to the ratio of the number of atoms of a particular radioisotope to the total number of atoms of the element. For Tc, the radionuchdic specific activity is the number of Tc atoms to the total number of Tc and Tc atoms. Because all isotopes of an element ate chemically identical, a low specific activity may lead to a low yield in the synthesis of a radiopharmaceutical if a significant proportion of the reagents is consumed by the undesited isotopes. 

The main reaction of this type has been the reductive cyclization of nitropyridine derivatives carrying an o-amino ester or o-aminocarbonyl substituent. These cyclize in situ via the o-diamino derivative to give pyridopyrazines of known constitution, either for establishment of structure of products obtained in the ambiguous Isay synthesis (see Section 2.15.15.6.1), or in the synthesis of aza analogues of biologically active molecules. 

The imidazole nucleus is often found in biologically active molecules,3 and a large variety of methods have been employed for their synthesis.4 We recently needed to develop a more viable process for the preparation of kilogram quantities of 2,4-disubstituted imidazoles. The condensation of amidines, which are readily accessible from nitriles,5 with a-halo ketones has become a widely used method for the synthesis of 2,4-disubstituted imidazoles. A literature survey indicated that chloroform was the most commonly used solvent for this reaction.6 In addition to the use of a toxic solvent, yields of the reaction varied from poor to moderate, and column chromatography was often required for product isolation. Use of other solvents such as alcohols,7 DMF,8 and acetonitrile9 have also been utilized in this reaction, but yields are also frequently been reported as poor. 

Abstract A -Heterocyclic carbene complexes produced on industrial scale are presented in this chapter along with a discussion about their production. Details of processes employing NHC complexes on pilot to industrial scales are discussed. These are frequently oriented towards the synthesis of biologically active molecules, however, examples are given for rubber formation and for 1-octene synthesis, a comonomer for polyethylene synthesis. 

Enantiomerically pure amines are extremely important building blocks for biologically active molecules, and whilst numerous methods are available for their preparation, the catalytic enantioselective hydrogenation of a C=N bond potentially offers a cheap and industrially viable process. The multi-ton synthesis of (S)-metolachlor fully demonstrates this [108]. Although phospholane-based ligands have not proven to be the ligands of choice for this substrate class, several examples of their effective use have been reported. 

He is an author of more than 150 papers published in international scientific journals. His scientific interests cover the synthesis of biologically active molecules and the development of new methodologies directed to synthesis automation applied to drug discovery and drug optimization. 

The principal classes of reported heterogeneously catalyzed reactions and the synthesis of biologically active molecules by heterogeneous diastereoselective catalysis are covered in a recent review by De Vos and coworkers [86],... 

Without doubt, multicomponent reactions have become an attractive tool for the synthesis of biologically active molecules. In this regard, Jeong et al. reported an interesting domino synthesis of bicyclopentenones [50]. They employed a bimetallic system consisting of [Pd2(dba)3(CHCl3)] and... 

Peroxidases have been used very frequently during the last ten years as biocatalysts in asymmetric synthesis. The transformation of a broad spectrum of substrates by these enzymes leads to valuable compounds for the asymmetric synthesis of natural products and biologically active molecules. Peroxidases catalyze regioselective hydroxylation of phenols and halogenation of olefins. Furthermore, they catalyze the epoxidation of olefins and the sulfoxidation of alkyl aryl sulfides in high enantioselectivities, as well as the asymmetric reduction of racemic hydroperoxides. The less selective oxidative coupHng of various phenols and aromatic amines by peroxidases provides a convenient access to dimeric, oligomeric and polymeric products for industrial applications. 

The dihydro-2//-1-benzopyran skeleton is found in many biologically active compounds. Such moieties have also been used in the synthesis of other biologically active molecules [16-18]. Hence their synthesis has received attention. Some catalysts used for formation of dihydro-2//-1-benzopyran include (Ph3P)2PdCl2, [19] I2 [20], and Sc(OTf)3 [21]. Few of these methods are highly catalytic in nature or have been reported to use environmentally friendly reagents. For example,... 

The development of new methods for the synthesis of homoallylic amine derivatives is an important area of synthetic efforts. Homoallylic amines are extremely important compounds as biologically active molecules [1], The Lewis acid-mediated reactions of imines with allyl silanes are among the most efficient for... 

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