Grignard allylmagnesium chlorid

Mg. Li and co-worker first reported magnesium-mediated Barbier-Grignard allylation of benzaldehyde in water (Eq. 8.73).172 Recently, a study was completed in which some water-tolerant allylating agents were prepared in situ from allylmagnesium chloride and various metallic salts reacted with aldehydes in THF-FLO to afford the desired homoallylic alcohols.173... 

Glyoxal-sodium bisulfite, 30, 86 Glyoxylic acid, w-butyl ester, 35, 18 ethyl ester, diethyl acetal, 35, 59 Grignard reaction, addition to ethyl sec-butylidenecyanoacetate, 35, 7 allylmagnesium bromide with of,(3-di-bromoethyl ethyl ether, 36, 61 allylmagnesium chloride with a,/3-di-bromoethyl ethyl ether, 36, 63 ethylmagnesium bromide with tin tetrachloride, 36, 86... 

Similar to the formation of allylmagnesium chloride (25), the oxidative addition of allyl halides to transition metal complexes generates allylmetal complexes 26. However, in the latter case, a 7i-bond is formed by the donation of 7i-electrons of the double bond, and resonance of the n-allvl and 7i-allyl bonds in 26 generates the 7i-allyl complex 27 or (/ -allyl complex. The carbon-carbon bond in the 7i-allyl complexes has the same distance as that in benzene. Allyl Grignard reagent 25 is prepared by the reaction of allyl halide with Mg metal. However, the 7i-allyl complexes of transition metals are prepared by the oxidative addition of not only allylic halides, but also esters of allylic alcohols (carboxylates, carbonates, phosphates), allyl aryl ethers and allyl nitro compounds. Typically, the 7i-allylpalladium complex 28 is formed by the oxidative addition of allyl acetate to Pd(0) complex. 

The best example of a preparation of an olefinic alcohol by this method is that of l-penten-5-ol from allylmagnesium chloride and ethylene oxide (60%). Acetylenic alcohols are made in fair yields from sodium acety-lides or acetylenic Grignard compounds and ethylene oxide. ... 

Bis(silyl)ketene acetals undergo silatropic ene reaction with nitrosobenzene to give N-hydroxyamino acid derivatives. When allylmagnesium chloride is reacted with nitroarenes, unstable adducts result. Reduction of these adducts with LAH in the presence of palladium on charcoal leads to A -allyl-W -aryl-hydroxylamines (73 Scheme 15). With alkyl Grignard reagents this reaction is negligible. ... 

In order to obtain analogs of 1,2-dihydroisoquinolines in which the aromatic carbocycle is replaced by various heteroaromatic systems, the furopyridines (19), the thieno[3,2-c]pyridines (20), and the thieno[2,3-c]-pyridines (21) were synthesized (70BSB301 71JHC57). By Grignard coupling of 4-chloro-19 with allylmagnesium chloride in the presence of catalytic... 

A wide variety of Grignard reagents and organolithium complexes participate in reactions with Ph3SiCl to afford organosi-lanes. Thus the reaction of allylmagnesium chloride with PhsSiCl... 

There are several methods that are useful in particular cases and special substrates for enolate formation. Although most of these protocols found no application in asymmetric synthesis, some are briefly mentioned. Nonenolizable or slowly enolizable carboxylic esters, thioesters, or amides are converted into ketone enolates by treatment of a combination of allylmagnesium chloride and LDA or n-butyllithium. The twofold addition of the Grignard reagent is suppressed by rapid in situ deprotonation. As illustrated in Scheme 2.56, the enolate 185a forms with remarkable diastereoselectivity as proven by conversion into the silyl enol ether 185b [175]. 

Addition of allylmagnesium chloride to the aldehyde 32a occurred with fair syn selectivity, producing the homoallylic alcohol 44. This inversion of facial selectivity in comparison with the other reactions of 32 (Scheme 10), and also with a wide range of other A -monoprotected a-amino aldehydes, with Grignard reagents 44,45 including allylic ones 46), have been rationalized with the. s>v7-selective chair-like transition state P (Scheme 13), involving a sterically controlled approach of the allylic nucleophile to the Re face of the carbonyl (Felkin-Anh) (41,42). 

TT-Allylpalladium chloride (36) reacts with the nucleophiles, generating Pd(0). whereas tr-allylnickel chloride (37) and allylmagnesium bromide (38) reacts with electrophiles (carbonyl), generating Ni(II) and Mg(II). Therefore, it is understandable that the Grignard reaction cannot be carried out with a catalytic amount of Mg, whereas the catalytic reaction is possible with the regeneration of an active Pd(0) catalyst, Pd is a noble metal and Pd(0) is more stable than Pd(II). The carbon-metal bonds of some transition metals such as Ni and Co react with nucleophiles and their reactions can be carried out catalytic ally, but not always. In this respect, Pd is very unique. 

D. a-Allyl- -bromoelhyl ethyl ether. The same apparatus is used as in the preparation of allylmagnesium bromide. The flask is charged with an amount of the Grignard solution (part C) equivalent to 2.78 moles of allylmagnesium bromide (or chloride) and cooled in an ice bath. A solution of 580 g. (2.5 moles) of o , 3-dibromoethyl ethyl ether (part B) in an equal volume of anhydrous ether is added slowly with stirring over a period of 3-4 hours. The mixture is allowed to stand overnight and is then hydrolyzed with 75 ml. of 20% acetic acid followed by 500 ml. of water. The ether layer is separated, washed with four 100-ml. portions of 10% aqueous sodium bicarbonate solution followed by four 100-ml. portions of saturated aqueous sodium chloride solution, dried over 100 g. of anhydrous calcimn sulfate, and distilled under reduced pressure. The yield of colorless a-allyl-/3-bromoethyl ethyl ether is 370-396 g. (77-82% based on the a, 3-dibromoethyl ethyl ether), b.p. 72-75°/21 mm., 1.4600-1.4606. 

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