Ketones from organometallic compounds

The organometallic chemistry of vanadium has been surveyed in COMC (1982) and COMC (1995).152 153 The chemical and biological importance of vanadium was reviewed in a dedicated edition of Coordination Chemistry Reviews.1 4 Relevant synthetic aspects of vanadium chemistry have also been reviewed,155-158 including early report by Hirao et al. on formation of ketones from organovanadium compounds and acid chlorides.159... 

There are three one-step syntheses from ketones and organometallic compounds. 

The usual synthesis of the carbinols 92 is carried out by reaction of an ester with a thienyllithium or Grignard reagent an alternative approach118 (from a dithienyl ketone and organometallic compound) has been used recently, however. Dehydration to the thiambutene is most often achieved by treatment with hydrogen chloride in a solvent (normally ethanol or acetic acid), but it has been found that trifluoroacetic acid gives the same result under very mild conditions.119... 

There are three one-step syntheses from ketones and organometallic compounds. We have used M to indicate the metal—it might be Li or MgX (in other words, the organometalhc could be an organolithium or a Grignard reagent). 

You have already had considerable experience with carbanionic compounds and their applications in synthetic organic chemistry The first was acetyhde ion m Chapter 9 followed m Chapter 14 by organometallic compounds—Grignard reagents for example—that act as sources of negatively polarized carbon In Chapter 18 you learned that enolate ions—reactive intermediates generated from aldehydes and ketones—are nucleophilic and that this property can be used to advantage as a method for carbon-carbon bond formation... 

Zirconium tetrachloride is instantly hydrolyzed in water to zirconium oxide dichloride octahydrate [13520-92-8]. Zirconium tetrachloride exchanges chlorine for 0x0 bonds in the reaction with hydroxylic ligands, forming alkoxides from alcohols (see Alkoxides, METAl). Zirconium tetrachloride combines with many Lewis bases such as dimethyl sulfoxide, phosphoms oxychloride and amines including ammonia, ethers, and ketones. The zirconium organometalLic compounds ate all derived from zirconium tetrachloride. 

D. A. Shirley, The Synthesis of Ketones from Acidhalides and Organometallic Compounds of Magnesium, Zinc and Cadmium, Organic Rcaktions, Vol. VIII, 28 (1954). 

Organometallic compounds or carbanions undergo a number of reactions in which the carbanion or carbanion-like moiety of the organometallic compound acts as a nucleophilic displacing agent. Examples are the formation of hydrocarbons from alkyl halides, alkyl halides from halogens, and ketones from acid chlorides or esters. The latter two reactions are closely related to the base-catalyzed condensations and are perhaps additions as well as displacement reactions. Related addition reactions are the carbonation of organometallic compounds and the addition to ketones or aldehydes. 

The formation of chiral alcohols from carbonyl compounds has been fairly widely studied by reactions of aldehydes or ketones with organometallic reagents in the presence of chiral ligands. Mukaiyama et al. 1081 obtained excellent results (up to 94% e.e.) in at least stoichiometric addition of the chiral auxiliary to the carbonyl substrate and the organometallic reagent. 

When a nucleophile containing a heteroatom reacts at a carboxyl carbon SN, reactions occur that convert carboxylic acid derivatives into other carboxylic acid derivatives, or they convert carbonic acid derivatives into other carbonic acid derivatives. When an organometallic compound is used as the nucleophile, SN reactions at the carboxyl carbon make it possible to synthesize aldehydes (from derivatives of formic acid), ketones (from derivatives of higher carboxylic acids), or—starting from carbonic acid derivatives—carboxylic acid derivatives. Similarly, when using a hydride transfer agent as the nucleophile, SN reactions at a carboxyl carbon allow the conversion of carboxylic acid derivatives into aldehydes. 

Selective 1,4-additions of organometallic compounds to o ,/Tun saturated ketones can also be achieved starting from organocopper and organozinc reagents. We will treat this in Section 10.6. 

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