Patent GB-883622-A (GB)
Title: Vinylphenyl boronic compounds and intermediates therefor
IPC: C07F5/02
Filed: 1958-09-04
Abstract: The invention comprises vinylphenyl boronic compounds of the general formula <FORM:0883622/IV (b)/1> wherein R and R1 may be the same or different and (a) are hydrogen, substituted or unsubstituted hydrocarbon groups and salt-forming radicals, preferably alkali metal or cations of organic bases and quaternary ammonium hydroxides, or (b) are substituted or unsubstituted hydrocarbon groups bonded to each other or to other R and R1 groups on adjoining boronic units of the above formula preferably through a group containing carbon and/or nitrogen, or wherein R and R1 together form the remaining portion of a boroxole ring, i.e. the compounds are vinylphenyl boroxoles of the formula <FORM:0883622/IV (b)/2> The vinylphenyl boroxoles may be made by dehydrogenating an ethylphenyl boroxole by heating at reflux temperature in an inert solvent in the presence of a dehydrogenation catalyst such as palladium on charcoal.  The vinylphenyl boroxoles may also be made by heating the ethylphenyl boroxole with an N-haloimide, preferably a N-halogensuccinimide, and then dehydrohalogenating the resulting a -haloethyl-phenyl boroxole, preferably between 75 DEG C. to 175 DEG C.  A vinylphenyl boronic acid is made by hydrating the corresponding vinylphenyl boroxole and may be reacted with a base to form a salt.  The esters are made by refluxing the vinyl phenyl boroxole or vinylphenyl boronic acid with an alcohol, or by ester interchange in the presence of an acid catalyst using an ester of an alcohol boiling below 175 DEG C. and an alcohol corresponding to the ester desired.  Esters may be formed from saturated, unsaturated or halogenated monohydric alcohols, polyhydric alcohols or dialkanolamines.  Examples describe the preparation of (1) (a) ethylbromobenzene from ethylbenzene and bromine, (b) p-ethylphenylboronic acid by reacting an ethylbromobenzene Grignard compound with n-butyl borate, decomposing the mass with sulphuric acid, making alkaline and removing butanol and acidifying with hydrochloric acid, (c) p-ethylphenyl boroxole by refluxing the boronic acid in toluene, (d) p-a -bromoethylphenyl boroxole or p-a -chloroethyl-phenyl boroxole with an N-halosuccinimide; (2) p-vinylphenyl boroxole by heating p-a -bromoethylphenyl boroxole with quinoline or other inorganic or organic bases, and p-vinyl-phenyl boronic acid by pouring the boroxole into water, acidifying and extracting with ether; (3) o and m-vinylphenyl boroxoles and boronic acids; (4) (a) vinylphenyl boroxoles by dehydrating the vinylphenyl boronic acids; (10)-(14) sodium, potassium and tetraethanolammonium salts of vinylphenyl boronic acids; esters such as (15) imino diethyl (p-vinylphenyl) boronate, (16) imino-isopropyl (o-vinylphenyl) boronate, (17) N-methylimino-diethyl (o-vinylphenyl) boronate and other esters of N-(hydrocarbon) dialkanolamines, (18) dibenzyl (p-vinylphenyl) boronate, (19) dialkyl (p-vinylphenyl) boronate, (21) di-n-butyl (p-vinylphenyl) boronate, (22) di-(3-chloropropyl)(p-vinylphenyl) boronate (23) mono-phenyl and di-phenyl (p-vinylphenyl) boronates, (24) dicyclohex-2-enyl (p-vinylphenyl) boronate, (25) glyceryl, and (26) ethylene glycol (p-vinylphenyl) boronates are prepared by conventional methods; o p  and/or m isomers of vinylphenyl boronic acid may also be used. Other alcohols specified in the examples for making esters include methalkyl alcohol, furfuryl alcohol, ethylene glycol monoallyl ethers and monoacylates, alkoxy- or halo-propanols, b -nitroethanol and hydroxyketones.