Addition of organomagnesium compounds

Addition of organomagnesium compounds to polarized multiple bonds O OMgX OH... 

Addition of organomagnesium compounds (Grignard reagents), generated from organohalides and magnesium metal, to electrophiles. 

Similar acryloyl imidazolidinones have been used for the asymmetric 1,4-addition of organomagnesium compounds in the presence of a Lewis acid. The diastereoselectivity is variable and was found to be highly depending on the nature of all substrates. ... 

The enantioselective addition of organomagnesium compounds to ketones can be most conveniently performed by using a chiral auxiliary in the substrate molecule. Primary aUsyhnagnesium reagents react with aryl and heteroaryl ketones in the presence of magnesium TADDOLate at — 100°C, yielding products with up to 98% ee (equation 143). Chiral a-ketoacetals 214, prepared in two steps from a-substituted cinnamic aldehydes, add organomagnesium species with up to 98% diastereoselectivity (equation 144). 

A wealth of papers has been published on the kinetics and mechanism of the addition of organomagnesium compounds to ketones, nitriles, etc. It is not... 

Readily available THF solutions of LnCl3,2LiCl (Ln = La, Ce, Nd) have been found to be superior promoters for the addition of various organometallic reagents to ketones.85 They also catalyse efficiently the addition of organomagnesium compounds to imines. 

Copper(i) catalysis of the addition of organomagnesium compounds to alkynes has been observed, but stoichiometric organocopper reagents, derived from organomagnesium compounds, are more effective in the absence of other activating features [4],... 

Addition of Organomagnesium Compounds to Carbon-Nitrogen Multiple Bonds... 

Both 1,2- and 1,4-addition of organomagnesium compounds to a,3-ethylenic imines has been reported [E, 24]. The latter has been used in tandem addition-alkylation sequences, e.g. [25]. 

While the addition of organomagnesium compounds to nitrones was reported over 80 years ago [36], only occasional examples were described until recently [37-40] ... 

Synthesis of ketones via addition of organomagnesium compounds to nitriles... 

The addition of organomagnesium compounds to the carbonyl group of aldehydes and ketones has a long history, and remains one of the most important reactions for carbon-carbon bond formation. While the overall reaction is simple, it is susceptible to a number of side-reactions, and its... 

The stereochemistry of addition of organomagnesium compounds to ketones is governed by similar factors to those influencing their addition to aldehydes (see Section 6.1.1). For addition of achiral organomagnesium compounds to a-chiral ketones, steric approach control is commonly observed, but chelation control may also operate [63, 64], It is noteworthy that a pioneering asymmetric synthesis — one of the first which could be regarded as virtually stereospecific, was of this type [65] ... 

The stereochemistry of conjugate addition of organomagnesium compounds to a,[3-unsaturated ketones is governed by similar considerations to those governing addition to saturated ketones recent examples include diastereoselective additions to both acyclic (6) [77] and cyclic [78] (7) enones. 

A special case of conjugate addition involves diaryl ketones. As noted in Section 4.2, conjugate addition of organomagnesium compounds may lead to products formally derived from addition to a ring. Such reactions are favoured by conditions promoting electron transfer, particularly when polar addition to the carbonyl group is sterically hindered [3]. 

Addition of organomagnesium compounds to the triple bond of a nitrile, followed by hydrolysis of the resulting imine,... 

---