With methylmagnesium bromide

The reaction of l,4-bis(trimethylsilyl)-l,3-butadiyne (174) with disilanes, followed by treatment with methylmagnesium bromide, produces i,l,4,4-tetra(-trimethylsilyl)-l,2,3-butatriene (175) as a major product[96]. The reaction of octaethyltetrasilylane (176) with DMAD proceeds by ring insertion to give the six-membered ring compounds 177 and 178[97], The l-sila-4-stannacyclohexa-2,5-diene 181 was obtained by a two-step reaction of two alkynes with the disilanylstannane 179 via the l-sila-2-stannacyclobutane 180[98],... 

Make a molecular model of 7 7 dimethylbicyclo[2 2 l]heptan 2 one Two diastereomenc alcohols may be formed when it reacts with methylmagnesium bromide Which one is formed in greater amounts ... 

Smid and coworkers have developed a straightforward and effective method for the synthesis of 4 -vinylbenzo-15-crown-5. In this method, 3,4-dihydroxybenzaldehyde is converted into the crown in the usual fashion and then the side chain is transformed by successive treatment with methylmagnesium bromide and then toluenesulfonic acid to effect dehydration. The overall yield is about 20%. 

Reaction of 17j -acetoxy-3,3-ethylenedioxy-5a-androstan-l-one (1) with methylmagnesium bromide followed by treatment with acid and reacetylation affords the 1-methyl-A -3-ketone (3). The configuration of carbon-1 of the intermediate (2) has not been established/ ... 

The 11-keto group is relatively difficult to attack, due to steric hindrance. However, reaction of 3j -hydroxy-5a-androstane-l 1,17-dione (37) with methylmagnesium bromide at 25° unexpectedly gives a 30% yield of 1 la,17a-dimethyl-5a-androstane-3j5,lljS,17i -triol (38) in addition to the 17-monomethyl product (39). 

The 17i -hydroxy-16-ketone (47) on treatment with methylmagnesium bromide provides the 16a-methyl compound (48). ... 

The C-20 epimeric diacetates (69) and (70) are obtained in a total yield of 30% by acetylation of the mixture formed from 21-acetoxy-3j -hydroxy-pregn-5-en-20-one (68) with methylmagnesium bromide. ... 

Bromination of the enolate anion from the reaction of 3j -acetoxypregna-5,16-dien-20-one (1) with methylmagnesium bromide in the presence of cuprous chloride affords (after treatment with sodium iodide to dehalo-genate any 5,6-dibromide) a mixture of 17a-bromo- and 17)5-bromo-16a-methyl compounds (11) and (12) in a ratio 9 1. The 17a-iodides can be obtained in an analogous reaction. 

In the estrone series diaxial cleavage of the 6a,7a-epoxide (10) with methylmagnesium bromide affords (11) in 60% yield. ... 

The 16a,l7a-epoxide (12) can be made to react with methylmagnesium bromide or methyllithium as well as phenyllithium to yield (13a) and (13b), respectively, after ketal cleavage. 

The actual mechanism by which a particular reaction proceeds strongly depends on the nature of the organomagnesium reagent. For instance benzophenone reacts with methylmagnesium bromide by a polar mechanism, while the reaction with t-butylmagnesium chloride proceeds for steric reasons by a SET-mechanism. 

Nitriles (RC=N) react with Grignard reagents (R MgBr). The reaction produc from 2-methylpropanenitrile with methylmagnesium bromide has the fol lowing spectroscopic properties. Propose a structure. 

Thiocarbonyl tetrachloride, 46, 21 m Thiocresol (Warning), 47, 107 Thionyl chloride, 46, 16 98 Thiophosgene 46, 21 Thiophosphoryl chloride, reaction with methylmagnesium bromide to i lelci tetramethylbiphosphine disulhdc 46,102... 

When y-lactone 14 is treated with methylmagnesium bromide in THF at -78 °C, a carbonyl addition reaction takes place and gives, after aqueous workup, a hemiketal that is subsequently converted to... 

In the same way, furanothiepin 6 is obtained by esterification of the corresponding diacid, then converted with methylmagnesium bromide to the highly reactive diol 7, which gives a eycloadduct with iV-phenylmaleimide in 65% overall yield67 (see Section 2.2.5.). 

Ring-opening products derived from primary amines are attractive precursors for the preparation of (3-lactams [57]. With methylmagnesium bromide as the base, diamino esters 33 cyclized readily in THF and stereospecifically generated anti-3-amino- 3-lactams 34 (Table 12.15). 

Trichlorosilanc reacts with allyl halides under mildly basic conditions, subsequent treatment with methylmagnesium bromide giving rise to allyl(trimethyl)silanes15-16. 

In the presence of bis(lriphenylphosphane)nickel dichloride both tram-1 and m-1 react with methylmagnesium bromide affording cis-2, trans-2 and 3 in a 19 1 5 ratio72c. It should be noted that the methyl group is introduced at the sterically more hindered carbon and this... 

Scheme 9.4 shows some representative reactions of allylic and alkenyl silanes. Entry 1 involves 3-trimethylsilylcyclopentene, which can be made by hydrosilylation of cyclopentadiene by chlorodimethylsilane, followed by reaction with methylmagnesium bromide. 

The following reaction would take place when 4-hydroxy-2-butanone is treated with methylmagnesium bromide ... 

The use of the zinc-copper couple to effect the reduction of the methanesulfonate 168 with rearrangement furnished 169 (Scheme 20.34) [10]. Treatment of 168 with methylmagnesium bromide in the presence of copper(I) cyanide to induce an SN2 -type reaction produced the methylated adduct 170. The half-life of the Myers-Saito cyclization of 169 is 66 h at 37 °C, whereas that of 170 is 100 min. The faster rate of cyclization for 170 has been attributed to a steric effect favoring the requisite s-cis or twisted s-cis conformation. 

Thiocarbonyl tetrachloride, i6, 21 Thionyl chloride, 45, 16, 98 Thiophosgene, 45, 21 Thiophosphoryl chloride, reaction with methylmagnesium bromide to yield tetramethylbiphosphine disulfide, 45,102 Toluenesulfonybromide, 46, 88 Trichloroacetyl fluoride, 46, 6 1,1,3-Trichloiio- -nonane, 46,104 Tricyclo[2.2.1.0 ]heptan-3-ol, 45,... 

II, 20-dione, which is reacted with methylmagnesium bromide in the presence of lithium bromide to give 3a-hydroxy-16a-methylpregnan-ll,20-dione (27.1.39), after which a Ha-hydroxyl group is added. This is done by a reaction with acetic anhydride in the presence of p-toluenesulfonic acid, forming the 3-acetoxy-17-enolacetate 27.1.40, which is epoxidized by perbenzoic acid 27.1.41, and the product is hydrolyzed by an alkali to give an oxyketone... 

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