Current Organic Chemistry - Volume 19, Issue 2, 2015

The Review reports the recent developments of palladium-catalyzed nucleophilic substitution of allylic alcohols and allylic amines used as electrophiles. The poor ability of the hydroxyl and amino groups to serve as good leaving groups has been overcome by the employment of additives which promote the palladium-catalyzed C-N and C-O bond cleavage. However, allylic alcohol and amine activation can be achieved by using appropriate catalytic systems or solvents, without any external activators. Significant expansion of the nucleophile scope allows to obtain various allylic compounds through the regio- and stereoselective formation of carbon-carbon and carbonheteroatom bonds.

Transition-metal-catalyzed direct C-H bond functionalizations have attracted considerable attention around the world for almost half a century. In the past decades, great efforts have been made for the development of late transition metals, mainly due to some advantages in terms of the diversity and high efficiency of the catalysts. However, their application was limited on account of their relatively high price, low natural abundance and partly strong toxicity. Cobalt as compared to precious transition metals has shown great potential in the C-H bond functionalizations because of its low cost, unique reactivity profiles and easy availibility in the earth’s crust. This review provides recent advances in direct C-H bond functionalizations mediated by cobalt from C-C and Cheteroatom bond forming reactions.

Aryltriazenes have emerged as highly powerful and versatile building blocks in a variety of synthetic transformations, which attracted extensive attentions due to their advantages of good reactivity, well stability, ready availability, operational simplicity and diverse transformation. In this review, we summarize the current progresses involving aryltriazenes as starting materials or active intermediates for various synthetically useful applications via C-N/N-N bond cleavage.

Functionalized benzocycloheptenes are one of the most important classes of bicyclic framework that have been critically investigated in different areas of biological activities. Due to interesting skeleton and activities, synthetic chemists were inspired to synthesize them for better understanding of the basic knowledge associated with these compounds. Thus, this review aims to provide insight approaches for construction and functionalization of benzocycloheptene amines and renders useful details for further progress in the area of synthetic methodology. We believe that functionalized benzocycloheptene amine compounds and their various co-components, highlight the existence of numerous potential leads for the development of novel bioactive agents.

The Hirao reaction, an important tool for the establishment of a P-C bond, was developed further by finding that the reaction of >P(O)H species, such as dialkyl phosphites, alkyl phenyl-H-phosphinates and diarylphosphine oxides with bromoarenes may be carried out in the presence of P-ligand-free NiCl2 as the catalyst. The scope and limitations of this “greener” approach was studied in detail.