Magnesium, organo- compounds examples

Alkylating agents that have been used include organo compounds of alkali metals, magnesium, aluminum, mercury, and zinc. The following equations illustrate some examples ... 

In many syntheses activation is not effected by sonochemical preparation of the metal alone but rather by sonication of a mixture of the metal and an organic reagent(s). The first example was published many years ago by Renaud, who reported the beneficial role of sonication in the preparation of organo-lithium, magnesium, and mercury compounds [86]. For many years, these important findings were not followed up but nowadays this approach is very common in sonochemistry. In another early example an ultrasonic probe (25 kHz) was used to accelerate the preparation of radical anions [87]. Unusually for this synthesis of benzoquinoline sodium species (5) the metal was used in the form of a cube attached to the horn and preparation times in diethyl ether were reduced from 48 h (reflux using sodium wire) to 45 min using ultrasound. 

Like their aryl and alkenyl counterparts, alkynylboronic adds can be made by displacement of magnesium or lithium acetylides with borate esters. For example, Mat-teson and Peacock have described the preparation of dibutyl acetyleneboronate from ethynylmagnesium bromide and trimethyl borate [294]. The C-B hnkage is stable in neutral or acidic hydrolytic solvents but readily hydrolyzes in basic media such as aqueous sodium bicarbonate. Brown and co-workers eventually applied their organo-lithium route to boronic esters to the particular case of alkynylboronic esters, and in this way provided a fairly general access to this class of compounds [295]. 

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