Preparation from Polar Organometallics

The preparation of functionalized aryl boronic reagents can be achieved by directed metallation followed by a transmetallation of aryllithiums with organoboron compounds. Thus, Caron and Hawkins have described a directed ortho-metalla-tion of aryl neopentyl esters such as 1 for the synthesis of substituted ortho-horo-nyl neopentyl benzoates using lithium diisopropylamide (LDA) as the base and B(OiPr)3 as an in situ trap [3]. The crude boronic acids obtained by acidic hydrolysis were subsequently treated with ethanolamine and converted to stable diethanolamine complexes such as 2. This methodology allows the preparation of a new class of boronic acids with ortho-carbonyl substituents and other functionalities 

Copyright 2005 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-31131-9 

2 Preparation and Reaction of Functionalized Aryl and Heteroaryl Boranes 49 

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The monomeric catalyst fraction showed similar R[ values as the metathesis products, which complicated the chromatographic separation and recycling procedure. Immobilization of the ruthenium catalyst on a dendrimer was anticipated to facilitate the chromatographic separation. Indeed, the presence of multiple (polar) organometallic sites on the dendrimer periphery resulted in stronger adsorption interactions between the dendritic catalyst and the silica and thus a better separation from the product. Two types of dendritic catalysts were prepared in which... 

Table 1 gives a qualitative comparison of the reactivities of a number of representative polar organometallics towards n-butyl bromide. From this table, working temperature ranges for preparative alkylations of structurally analogous polar organometallics can be derived. 

Perfluoroalkylcopper reagents have received more attention than perhaps any other perfluorinated organometallic compounds. They can be prepared from per-fluoroalkyl iodides and copper metal in polar solvents (such as DMSO, DMS,... 

Organohthium and organomagnesium compounds are stable species when prepared m suitable solvents such as diethyl ether They are strongly basic however and react instantly with proton donors even as weakly acidic as water and alcohols A proton is transferred from the hydroxyl group to the negatively polarized carbon of the organometallic compound to form a hydrocarbon... 

The present book contains nine chapters focusing on the design of imine and phosphorylide catalyst structures, the preparation of cycloaliphatic materials, polar/ nonpolar monomer copolymerizations, organometallic polymerizations in aqueous media, and current frontiers in ROMP and ADMET processes. Exactly forty years after the Nobel Prize for Ziegler and Natta, we give a concise description of the state of the art in these fascinating and rapidly developing fields. The authors present, likewise, viewpoints from the forefront of both academia and industrial research, so that basic science and polymer applications are equally covered. 

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