Hydromagnesiation

Hydromagnesiation (11, 163-164 12, 168-169). Cp2TiCl2-catalyzed syn-addition of isobutylmagnesium chloride to propargylic alcohols affords a stereoselective route to vinylmagnesium chlorides for further synthetic use. ... 

HYDROMAGNESIATION REACTION OF PROPARGYLIC ALCOHOLS (E)-3-PENTYL-2-NONENE-1,4-DIOL FROM 2-OCTYN-1-OL... 

Since then, hydromagnesiation of other unsaturated hydrocarbons such as conjugated dienes and acetylenes has been investigated intensively.5 6 Hydromagnesiation of 2-alkyl substituted 1,3-butadienes has been shown to proceed... 

Hydromagnesiation of 1-propynylic alcohols. The hydromagnesiation of alkynes (10,130) has been extended to propynylic alcohols (equation I), which provides a new route to terpenoids.1... 

Hydromagnesiation butenolides.1 Reaction of optically pure y-trimethylsilyl propargylic alcohols with isobutylmagnesium bromide catalyzed by Cp2TiCl2 (14,... 

The best potential precursors of the pentacyclopropylcyclopentadienyl cation 6+ have recently been prepared. The Grignard reagent 13, which was obtained by hydromagnesiation of easily accessible dicydopropylacetylene (12), gave, upon reaction with butyl formate and... 

The hydromagnesiation of acetylenes, catalysed by titano- and zirconocenes is well known. A regioselective reaction occurs only if one of the substituents on the triple bond is silicon or an aryl group. Studies on its mechanism were reported by Sato.2 7 Cai has applied this reaction for the synthesis of a number of polysubstituted alkenes (Scheme p).28-28 -2 ... 

Dicyclopentadienyltitanium dichloride is possibly superior to titanium tetrachloride as a catalyst. Nickel(ll) compounds are also active, but with these catalysts concurrent addition of the organomagnesium compounds to carbon-carbon multiple bonds (see Section 4.1) causes complications. Examples of hydromagnesiation by Grignard reagents are listed in Table 3.8. As will be seen from entries in Table 3.8, the stereochemistry of addition to alkynes is syn. The regiochemistry is also usually predictable in the relevant examples in Table 3.8, one regioisomer is obtained mainly or exclusively. In other cases, however, mixtures are formed [54]. 

In an interesting extension, hydromagnesiation of 1,6-heptadiene and 1,7-octadiene is reported, though without full experimental details, to result in cyclization [65] ... 

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