Grignard compounds addition

Diazirine, fluoromethoxy-nitrogen extrusion, 7, 224 Diazirine, methylvinyl-rearrangement, 7, 221 Diazirines addition reactions to Grignard compounds, 7, 2 0 as carbene precursors, 7, 236 IR spectra, 7, 203 microwave spectrum, 7, 199 molecular spectra, 7, 202-204 nitrogen extrusion, 7, 223 NMR, 7, 202 photoconversion to diazoalkanes, 7, 234 photoisomerization, 7, 221 photolysis, 7, 225-227 quantum chemical investigations, 7, 197 reactions... 

The stereochemistry of the 1,4-addition to A -octal-l-one and 1,1-di-methyl-A -octal-2-one has been investigated by House and Marshall, respectively. In summary, steric and stereoelectronic factors play a part in the mechanism of conjugate addition of Grignard compounds. With methylmagnesium iodide, the introduction of an axial methyl group into steroidal 5a-A -3-ketones (3) and 5 -A -3-ketones (6) is favored by stereo-electronic factors in the transition state. 

A further synthesis of 1-alkyl-diaziridines is the addition of Grignard compounds to the NN double bond of diazirines [Eq. (35) ]. The... 

Since the formation of the Grignard compound takes place at the metal surface, a metal oxide layer deactivates the metal, and prevents the reaction from starting. Such an unreactive metal surface can be activated for instance by the addition of small amounts of iodine or bromine. 

Alkylation of enamines Addition of amines to triple-bond compounds Addition of amines to aldehydes or ketones Reaction between Grignard reagents and formamides Reaction of phosphonates with aldehydes or ketones... 

The development of the Grignard-type addition to carbonyl compounds mediated by transition metals would be of interest as the compatibility with a variety of functionality would be expected under the reaction conditions employed. One example has been reported on the addition of allyl halides to aldehydes in the presence of cobalt or nickel metal however, yields were low (up to 22%). Benzylic nickel halides prepared in situ by the oxidative addition of benzyl halides to metallic nickel were found to add to benzil and give the corresponding 3-hydroxyketones in high yields(46). The reaction appears to be quite general and will tolerate a wide range of functionality. 

Vinylchromium compounds (12,137).6 These compounds can be obtained by reaction of vinyl triflates with CrCl2 catalyzed by NiCl2 in DMF. They undergo selective Grignard-type addition to aldehydes. Some commercial sources of CrCl2 do not require a catalyst, presumably because they contain a metal contaminant. 

Grignard compounds in the thiophene series were studied (20) and used for the synthesis of some thienylbutenols. The product obtained by the reaction of alpha-thienylmagnesium bromide with butadiene monoxide has been identified as 4-(2-thienyl)-buten-2-ol-l formed by 1-4 addition. Furthermore, the Grignard compounds were utilized for... 

Scheme 2.11. Michael additions of functionalized organocopper reagents derived from Grignard compounds.

Addition of organometallic reagents to nitro compounds is possible but is sparingly used. Reaction of aromatic nitro compounds with large excess of phenyl magnesium bromide produces hydroxylamines in moderate yield . Similar addition of Grignard compounds to nitromethane proceeds in low yield ° while addition of excess methyllithium to tertiary nitro compound 113 results in formation of hydroxylamine 114 (equation 83) . ... 

SCHEME 2. A termolecular mechanism for Grignard reagent addition to carbonyl compounds via... 

Chiral sulfinimines 236 are very useful intermediates for the preparation of enantiomer-ically pure primary amines 237 (equation 158) . This reaction has been applied to the synthesis of a-amino acids . For sulfinimines obtained from simple ketones, lithium reagents are preferable for the addition , while for cyclic ketones organomagnesium compounds gave the best results. Addition of alkyl and aryl Grignard compounds to sulfinimines, derived from 3- and 4-substituted cyclohexanones, proceeds with excellent diastereoselectivity, depending on the stereochemistry of the ring substituents rather than the sulfinyl group . 

In 2002, Furstner and coworkers reported that aryl halides react with Grignard reagents under the conditions previously used for the coupling of alkenyl halides. They proposed that the active iron species is Fe(MgX)2, a complex described by Bogdanovic and coworkers ° a few years earlier (Scheme 30). This iron(-II) species is formed by addition of four equivalents of the Grignard compounds to FeCl2. 

The reaction of aliphatic 1,5-Grignard compounds of 1,5-dibromopentane with dichlorophenylphosphine constituted the first synthesis of a phosphorinane derivative, 1-phenylphosphorinane (equation (3)). It is an air sensitive colourless oil with the characteristic strong smell of a phosphine. Addition of HgCl2 gives a solid product, m.p. 127 °C, With... 

Grignard-type Addition of Acetylenic Compounds to Imines... 

For example, the copper catalyzed addition of Grignard compounds to alkynyl substituted /(-lactones 55 delivers /S-allenic acids 56 in high yields [38], During these reactions, the central chirality of one of the stereogenic centers of the /Mactone is transferred to the axial chirality of the allene. 

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