Methallylmagnesium chloride

The present method is successful with a wide variety of ketones (see Table). Cyclic ketones (entries 1-4, 8) produce benzoannelated products in excellent overall yields. There is no need to purify the intermediate both the nucleophilic addition of methallylmagnesium chloride and the aromatic cyclization take place cleanly. Acyclic ketones (entries 5-7) also provide high yields of benzoannelated product. Aromatic ketones are particularly interesting substrates for this reaction since they provide substituted biphenyls, which are potentially useful materials for liquid crystal synthesis and whose preparation through classical methodology is often not straightforward. The conditions for the cationic cyclization step can be modified to accommodate acid-sensitive functionality. For example, cyclization of 3 to 4, the latter a precursor for 3-methyl-8,14-dehydromorphinan, was accomplished in 77% yield by treatment of 3 at... 

Methallylmagnesium chloride (l).5 The reaction of 1 with the a-oxoketene dithioacetal 2 provides a 1,2-adduct 3 that on treatment with HBF4 is converted into the aryl sulfide 4. 

Methallylmagnesium chloride, 139 Nickel carbonyl, 198 Organoaluminum reagents, 202 Organotitanium reagents, 213 Samarium(II) iodide, 270 Tin, 298... 

Magnesium iodide, 171 Magnesium-Methanol, 170 Magnesium methoxide, 352 Methallylmagnesium chloride, 139 Methylmagnesium bromide, 139, 195, 203, 214, 322... 

A new synthesis of propenyl ketones involves reaction of an ester with 2 equiv. of allylmagnesium chloride (or methallylmagnesium chloride) to form the tertiary... 

Coupling of alkyllithium and Grignard reagents with alkyl halides gives poor yields and if possible tends to produce mixtures of regio-and stereoisomers. However, effective procedures have been developed involving stoichiometric or catalytic use of Cu(I) salts.10 Thus, the copper-catalyzed substitution of iodide 7 by methallylmagnesium chloride 26 proceeds smoothly in 98 % yield. 

Bemannelation of ketones.1 This reaction can be effected by reaction of an allylic Grignard reagent such as methallylmagnesium chloride with the silyl ether of a 2-hydroxymethylene ketone as shown by conversion of 1 to 2 in 86% overall yield. 

Ruthenium-Catalyzed Hydrogenations. Ru-DuPhos complexes are commonly prepared by reacting [RuCl2(cod)] with methallylmagnesium chloride to generate [Ru(cod)(methallyl)2] which when treated with DuPhos and HX forms the catalytically active complex (DuPhos)RuX2. The procedure can be performed in a single pot or in stepwise fashion. Ru-DuPhos complexes effectively reduce a variety of substrates to provide chiral materials. 

Finally, the method was used to prepare allyl- and methallylmagnesium chlorides, the C-spectra of which were consistent with the expected dynamic allyl structure [10]. 

Stork [11], as well as Corey [12], have shown that methallylmagnesium chloride couples with allylic chlorides affording a mixture of 8, 2 and Sn2 products. However, Stork [11] has found that the use of hexamethylphosphoramide (HMPA) as a cosolvent allows the formation of the sole 8, 2 product 10, without any rearrangement of the double bond, after reaction with either cis- or trans-chlorides 9 [Eq. (4)]. 

As shown in Eq. (15) in Section II,B, a formal 1,2-rearrangement of an allyl group has been reported in the product of addition of allyl- or methallylmagnesium chloride to styrene (45). The rearrangement would appear to involve reversal of the addition step, followed by readdition. 

A much shorter synthesis of ( —)-statine (831) relies on the regiospecific addition of methallylmagnesium chloride to the C-2 carbonyl of 793c as a way of introducing the... 

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