Lithium organo- compounds

Thus, even 2,6-dibromo-l,4-quinone adds lithium organo compounds to give 4-alkyl-4-hydroxy-2,6-dibromo-2,6-cyclohexadien-l-ones125>. When bulky t-butyl groups are in the ortho positions of one of the carbonyl groups, such as in... 

Hydrolysis of 3/8-benzyloxy-14a,15a-epoxy-5a-cholest-7-ene with aqueous KOH-EtOH gave the rearranged triol (16) which with HCl-EtOH gave the enone (17). Treatment of 5a,10a-epoxy-A " -steroids with lithium organo-cuprates gave 11/3-substituted 5a-hydroxy-A -compounds and is exemplified by... 

Recent structural investigations on lithium organo(fluorosilyl)amides have revealed that the lithium cation can form aggregates with internal lithium coordination to fluorine, and mixed aggregates of the amide and LiF. Structural types such as (205), (206), (207) and (208) have been found for these compounds. 

The mechanism for coupling with these organometallic compounds could be illustrated as follows. First an organo-lithium (RLi) compound is prepared from the alkyl halide. In this case the alkyl halide is isopentylbromide. 

This procedure illustrates a general method for the preparation of alkenes from the pal 1 adium(Q)-cata1yzed reaction of vinyl halides with organo-lithium compounds, which can be prepared by various methods, including direct regioselective lithiation of hydrocarbons. The method is simple and has been used to prepare a variety of alkenes stereoselectively. Similar stoichiometric organocopper reactions sometimes proceed in a nonstereoselective... 

Unlike elimination and nucleophilic substitution reactions, fonnation of organo-lithium compounds does not require that the halogen be bonded to 5/) -hybiidized car bon. Compounds such as vinyl halides and aryl halides, in which the halogen is bonded to sp -hybiidized carbon, react in the sane way as alkyl halides, but at somewhat slower rates. 

The rearrangement of an ether 1 when treated with a strong base, e.g. an organo-lithium compound RLi, to give an alcohol 3 via the intermediate a-metallated ether 2, is called the Wittig rearrangement. The product obtained is a secondary or tertiary alcohol. R R can be alkyl, aryl and vinyl. Especially suitable substrates are ethers where the intermediate carbanion can be stabilized by one of the substituents R R e.g. benzyl or allyl ethers. 

Some new initiators soluble in hydrocarbons were described during the last few years. Organo-lithium compounds form 1 1 complexes with alkyls of Mg 134,135), Zn 136) or Cd l36), and their usefulness as initiators of anionic polymerization of styrene and the dienes was established 137). 

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