McMurry alkene synthesis

Accounts of die reductive coupling of two molecules of ketone via the McMurry alkene synthesis have been described66-68 earlier under Miscellaneous Aldols. 

Other reports of kinetic studies deal with mechanisms of thermal oxidation of a variety of simple ketones monitored via gas evolution (CO, CO2, H2, etc.), alkaline oxidation of aldehydes with copper and silver tellurates, [M (H2Te06)2] , and oxidation of acetals of simple aldehydes in aqueous acetic acid with (i) N-chlorobenzamide (H2OCI+ is the oxidant inferred) and (ri) W-chlorosaccharin. Accounts of the reductive coupling of two molecules of ketone via the McMurry alkene synthesis have been described earlier under Miscellaneous Aldols. 

The McMurry alkene synthesis has been reviewed, considering the mechanistic alternatives of carbene or pinacolate intermediates. ... 

Other Systems for the McMurry Alkene Synthesis Organotitanium Complexes, Titanium Oxides, Titanium Metal... 

Even the ease of retrieval or possible photocatalytic uses or such in alkene synthesis from the carbonyl compounds principal in biochemistry (McMurry reaction) apparently cannot compensate for this as Ti is unable to bind the primary substrate. Eor Al, Zr or Ti abundance cannot replace catalytic versatility with respect to various functions, that is... 

McMurry olefin synthesis. Lenoir has published a variation of the McMurry reaction for reductive coupling of ketones (6, 589). The actual reagent presumably is also TiCl2, but is produced by reduction of TiCU in THF or dioxane with zinc. This reagent in the presence of pyridine converts ketones into tetrasubstituted alkenes. The reaction is most satisfactory with symmetrical ketones mixtures of (E)- and (Z)-isomers obtain from unsymmetrical ketones, with the latter predominating. Strongly hindered ketones are reduced by the reagent to the secondary alcohol. 

The intermolecular McMurry reaction is first of all a suitable method for the synthesis of symmetrical alkenes. With a mixture of carbonyl compounds as starting material, the yield is often poor. An exception to this being the coupling of diaryl ketones with other carbonyl compounds, where the mixed coupling product can be obtained in good yield. For example benzophenone and acetone (stoichiometric ratio 1 4) are coupled in 94% yield. ... 

The McMurry procedure is a valuable method for the synthesis of highly substituted, strained alkenes such compounds are difficult to prepare by other methods. Diisopropyl ketone 6 can be coupled to give tetraisopropylethene 7 in 87% yield attempts to prepare tetra-t-butylethene however were not successful. ... 

Macrolactone synthesis 6,51, 71, 72, 94, 124,131,163,187,195 McMurry coupling 43 Medium ring synthesis 43,45,75, 77 Metathesis, Alkene (see Grubbs) Metathesis, Alkyne (see alkyne metathesis) Michael addition Intramolecular 166,166, 167,201 Intermolecular 57,84, 153, 166,204... 

Stuhr-Hansen has reported on a microwave-induced high yielding synthesis of alkenes by McMurry coupling of aldehydes and ketones. With microwave heating, the corresponding alkenes have been produced much faster with higher yields (>80%) as compared to conventional heating. 

The intermolecular McMurry carbonyl coupling reaction has been applied to the synthesis of a variety of symmetrically and, in certain cases, unsymmetrically substituted alkenes. 

McMurry-Fleming olefin synthesis. Two laboratories ° have reported the synthesis of the crowded alkene tetraisopropylethylene by reductive coupling of 2,4-dimethyl-3-pentanone yields are 6% and 12%. The NMR indicates that the isopropyl groups of this alkene are not equivalent. 

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