Kharasch additions carbonylation

Susuki and Tsuji reported the first Kharasch addition/carbonylation reactions of olefins 126 with CCI4 and carbon monoxide catalyzed by [CpMo(CO)3]2 127 and proposed a carbometalation mechanism (Fig. 37) [229]. A kinetic study disproved... 

Susuki and Tsuji reported the first Kharasch addition/carbonylation sequences to synthesize halogenated acid chlorides from olefins, carbon tetrachloride, and carbon monoxide catalyzed by [CpFe(CO)2]2 [101]. Its activity is comparable to or better than that of the corresponding molybdenum complex (see Part 1, Sect. 7). Davis and coworkers determined later that the reaction does not involve homolysis of the dimer to a metal-centered radical, which reduces the organic halide, but that radical generation occurs from the dimeric catalyst after initial dissociation of a CO ligand and subsequent SET [102]. The reaction proceeds otherwise as a typical metal-catalyzed atom transfer process (cf. Part 1, Fig. 37, Part 2, Fig. 7). 

Such complexes have been used in a variety of reactions hydrogenation [153], hydroformylation [154], carbonylation [154-156], cyclooligomerization [157 159], allylic substitution [160], Kharasch addition [161], reduction of bromides and iodides by sodium borohydride (Table 11-2 see Experiment 11-1, Section 11.7) [162],... 

Use of (PCy3)2Cl2Ru=CHPh (1) in Other Synthetie Transformations. As well as finding widespread use in metathesis, (1) has found applications as a catalyst for other important reactions. These include hydrosilylation of alk3Ties dehydrogenative condensation of alcohols and hydrosilylation of carbonyls intermolecular cyclotrimerization of terminal alkynes conversion of triynes to benzene derivatives Kharasch additions (Z)-selective cross-dimerization of ary-lacetylenes with silylacetylenes and hydrogenation of natural rubber. ... 

For reviews of the addition of organometallic compounds to carbonyl groups, see Eicher, T. in Patai, Ref. 2, p. 621 Kharasch, M.S. Reinmuth, O. Grignard Reactions of Nonmetallic Substances, Prentice-Hall Englewood Cliffs, NJ, 1954, p. 138. For a review of reagents that extend carbon chains by three carbons, with some functionality at the new terminus, see Stowell, J.C. Chem. Rev., 1984, 84, 409. 

Since Kharasch reported radical-mediated carboxylation of saturated hydrocarbons with phosgene as a radical trap in the 1940s [39], no successful radical acylation and carboxylation reactions have appeared. In intermolecular radical acetylations, biacetyl was used as a radical trap (Scheme 18) [44]. The addition of an alkyl radical to the carbonyl carbon of biacetyl gives the methyl ketone along with an acetyl radical. 

The effect of deuterium in The species, which is reduced in the catalytic cycle described above, need not be an alkyl halide, but may just as well be an easily reduced carbonyl compound like benzophenonc. Kharasch showed in 1941 [91] that though nicthylmagnesium bromide normally adds to benzophenone producing methylbenzhydrol in high yield, the addition of a few per cent of ferric chloride led to the production of henzopinacol instead of the addition product ... 

Kharasch and Tawney (1941) reported that copper salts catalyze 1,4-addi-tion of Grignard reagents to a,jS-unsaturated ketones. Gilman et al. (1952) first discovered that phenylcopper reacts with benzalacetophenone in a 1,4-addition. Subsequently House and associates (1966) have revealed the scope of the conjugate addition of cuprate complexes. Now alkyl, vinyl, and aryl groups can be introduced specifically at the p position of a,jS-unsaturated carbonyl compounds. Transfer of an allyl group from lithium diallylcuprate to 2-cyclohexenone is also known (House and Fischer, 1969). However, ethynyl, cyano, and hetero groups attached to the copper atom are difficult to transfer to electron-poor olefins. 

Preliminary work by Gutsche and Kharasch showed that under conditions in which a metaUocarbene was likely to be formed (e.g., EDA, Cu ), reaction commenced with electrophilic addition of the carbonyl oxygen atom, giving complex product mixtures dominated by enol ethers [179, 180]. In other words, the main adducts were products of formal O-H insertion via the enol tautomer of the... 

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