Lithium, organo- compounds 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. 

Also other reaction types have been dealt with in CHEC(1984) and CHEC-II(19%) like reduction to alcohols (e.g., sodium borohydride), Wolff Kishner reduction, nucleophilic addition via reaction with Grignard reagents or organo-lithium compounds, and formation of imine type functional groups (e.g., hydrazones). New examples are the reaction of... 

Lagow has carried out reactions between lithium atoms and organo-halogen compounds in the gas phase (19, 20). For example, when CC14 vapor was bled into a dense stream of lithium vapor and the mixture condensed at -196°C, the condensate behaved chemically as if it contained Li4C, e.g.,... 

Another potentially useful amination procedure utilizes the reaction of organo-lithium compounds with mixtures of methoxyamine and methyllithium (Eqn. (85)) 343> for example ... 

Many syntheses of useful compounds utilize the nucleophilic addition of a Grignard or organo-lithium reagent to form carbon-carbon bonds. For example, a key step in the synthesis of ethy-nylestradiol (Section 11.4), an oral contraceptive component, is the addition of lithium acetylide to a ketone, as shown in Figure 20.5. 

Reaction with organo-lithium compounds works well with all three examples one molecule of formaldehyde is lost but a CH2OH group is retained in the products 56, 57, and 58 from addition of vinyl, phenyl, and butyl lithium. This chemistry was used to make bertyodionol.7... 

Organotin compounds of this type can be further treated with Grignard reagents or organo-lithium or -sodium compounds, thus yielding a variety of mixed organotin derivatives for example, trialkyl- and tri(cyclohexyl)-tin... 

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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