Mini-Reviews in Organic Chemistry - Volume 5, Issue 2, 2008

The metal-catalyzed cross-coupling reaction of oxazoles is discussed in this review. Initially, preparation of metallated oxazoles (oxazole-M) and halo- and trifloyloxazoles (oxazole-X) is outlined. After that, comprehensive examples of Negishi, Stille, Suzuki-Miyaura, and Sonogashira reactions at each three position in oxazoles (C-2, C-4, and C-5) are detailed with showing both types of reactions [route A (reaction of oxazol-M and Ar-X) and route B (reaction of oxazole- X and Ar-M)].

This review covers the key advances in the study of Claisen rearrangement under microwave irradiation conditions. It surveys [3,3] sigmatropic rearrangements of vinyl allyl ethers, aryl allyl ethers, ortho-ester and aza Claisen rearrangements. Applications of the method for the synthesis of heterocyclic and natural compounds are surveyed.

Hybrid bidentate phosphoramidite ligands are a recent family of promising phosphorus ligands. The different classes (phosphoramidite-phosphine, phosphoramidite-phosphite, phosphoramidite-phosphinite, phosphoramidite-thioethers, phosphoramidite-amine, phosphoramidite-NHC, phosphoramidite-oxazoline) are presented along with the strategies used to access to these compounds. The main part of the review summarizes the results of the evaluation of these ligands in reactions catalyzed by transition metals/bidentate phosphoramidite ligands, such as hydrogenation, hydroformylation, conjugate addition and Tsuji-Trost reaction.

The purine ring system is undoubtedly among the most ubiquitous of all the heterocyclic compounds. In recent years modified purine structures both of natural and synthetic origin have been a rich source of biologically active materials. The halogen at 6 position of the purine moiety of the (RS)-9 or 7-(2,3-dihydro-5H-1,4-benzodioxepin-3-yl)-9H-or 7Hpurines shows an interesting reactivity which is presented and discussed. The anticarcinogenic potential of the target molecules is reported against the MCF-7 cancer cell line.

Bestatin, (2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl-L-leucine, is an effective inhibitor of the aminopeptidase N and other leucine and arginine aminopeptidases , having the selectivity toward the Aminopeptidase N (APN) and the Aminopeptidase B (APB) which are all metalloproteases belonging to the M1 aminopeptidase family. In spite of the poor selectivity and toxicity, so far, Bestatin is still the only marketed inhibitor of APN for cancer treatment. Considering that the inhibitor of APN is a promising agent to control and treat cancer, many efforts have been made to curtail the whole synthesis of the Bestatin and this mini-review will introduce the whole synthesis of Bestatin.

Pincer complexes have represented a group of very important species in organometallic chemistry in the last decade. Among these, phosphinite POCOP pincer complexes have recently been used profusely in metal mediated organic transformations due to the easiness on their synthesis, high thermal stability and enhanced catalytic activity. This minireview presents the evolution and recent advances in the chemistry and applications of this important group of compounds in different cross coupling reactions and other transformations relevant in organic synthesis.