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Waste‐Free and Facile Solid‐State Protection of Diamines, Anthranilic Acid, Diols, and Polyols with Phenylboronic Acid
Author(s) -
Kaupp Gerd,
NaimiJamal M. Reza,
Stepanenko Vladimir
Publication year - 2003
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200304793
Subject(s) - phenylboronic acid , anthranilic acid , chemistry , pyrogallol , stoichiometry , organic chemistry , pinacol , hydrolysis , yield (engineering) , catalysis , combinatorial chemistry , polymer chemistry , materials science , metallurgy
Abstract Phenylboronic acid ( 2 ) reacts quantitatively by ball‐milling in the solid state with o ‐phenylendiamine, 1,8‐diaminonaphthalene, anthranilic acid, pyrocatechol, pyrogallol, pinacol, bicyclic cis ‐diols, mannitol, and inositol to form the five‐ or six‐membered cyclic phenylboronic amides or esters. Catalysts or other auxiliaries are strictly excluded as they are not required and would have to be removed after the reactions. These varied model reactions provide pure protected products without the necessity of further purifying workup and the potential for protection chemistry is demonstrated. Some of the reactions can also be quantitatively performed if stoichiometric mixtures of the reactants are co‐ground or co‐milled and heated to appropriate temperatures either below the eutectics or above the melting points. The temperatures are much higher in the latter case. Similar reactions in solution suffer from less than 100 % yield of the mostly sensitive compounds that are difficult to purify and thus create much waste. The hydrolysis (deprotection) conditions of the products are rather mild in most cases. Therefore, this particularly easy access to heteroboroles, heteroborolanes, heteroborinones, heteroborines, and heteroborinines is highly valuable for their more frequent use in protective syntheses.