Propylmagnesium bromide, reaction

Thus, Diels-Alder condensation of 9 with methyl vinyl ketone affords the bicyclic adduct 24. The new ring is formed by approach of the dienophile from the face containing the nitrogen bridge, since this is in fact the least hindered side of the molecule (9a). Reaction of the side Chain ketone with propylmagnesium bromide then leads to intermediate 25 demethylation of the... 

It may be mentioned that the optical yield of the analogous reaction between methylneophyltrityltin menthoxide and z-propylmagnesium bromide is different at —15 °C and at 0 °C at —15 °C, optically active (-f)-z-propylmethylneophyltrityl-tin, (+)-(<53), is obtained (see Table 4) whereas at 0 °C optically inactive (63) is obtained 41). 

For the synthesis of Diels-Alder adducts a morphinan-6,8-diene system, as present in thebaine, is indispensable. Older publications started from thebaine and methyl vinyl ketone (but-3-en-2-one), yielding, after a Grignard reaction with propylmagnesium bromide, etorphine (13), a 6,14-endoethenomorphinan that is over 1000x as active as morphine and is used in veterinary medicine (Scheme 5.10). 

Sn2 Reactions with epoxides and aziridines are also synthetically useful. An example of epoxide cleavage with an organocopper reagent with sp carbon moieties is the enantioselective synthesis of (3S, 4S)-4-methyl-3-heptanol (53), an elm bark beetle (Scolytus multistriatus) pheromone [42]. The chiral epoxy oxazolidine 51 [43], prepared from (R)-phenylglycinol, reacted with a propylmagnesium bromide-derived cuprate at —70 °C to afford the oxazolidine 52 in 74% yield (Scheme 9.12). Compound 52 was converted into the target molecular 53 by conventional procedures. 

An interesting method for the introduction of substituents into the 2-position of the quinuclidine ring starting from 3-substituted A2-dehydroquinuclidines (126) has been described.47 By the reaction of methyl J2-dehydroquinuclidine-3-carboxylate (130) with iso-propylmagnesium bromide, 1,4-addition with formation of 2-iso-propyl-3-methoxycarbonylquinuclidine (131) took place instead of a sterically hindered Grignard reaction at the alkoxycarbonyl group. 

What compound would be expected as the major product from a Grig-nard reaction between (S)-2,3,3-trimethylbutanal and propylmagnesium bromide ... 

The ester (3) has been shown to be a useful starting point for the synthesis of Elaeocarpus alkaloids. Ester (3) is converted by several steps into the protected keto-aldehyde (4) this, by reaction with n-propylmagnesium bromide followed by a Jones oxidation of the product and then deprotection, gives the diketone (5). As... 

The ether 8 has also been used to prepare n-propyldiphenylcyclopropenyl cation 9 as either the perchlorate or fluoroborate by reaction with n-propylmagnesium bromide and subsequent hydride abstraction of the resulting impure 3-n-propyldiphenylcyclopropene with triphenylmethyl cation (equation 5). 

The fluoroborate of 11 could be prepared from the perchlorate or directly from the cyclopropene 10. This ion was used to synthesize tri-n-propylcyclopropene (12), either by direct reaction with n-propyllithium or by conversion of the cation to di-n-propylcyclopropenyl methyl ether (13) and reaction of this compound with n-propylmagnesium bromide. The cyclopropene was converted directly to the ion 14 with triphenylmethyl perchlorate (equation 6). 

The reaction of 1 molEq of n-propylmagnesium bromide with 1 molEq of diisopropyl ketone, a sterically crowded ketone, gave the normal addition reaction product in only low yields the major product of the reaction was the reduction reaction product, formed by the transfer of a /-hydrogen from the Grignard reagent to the ketone. Owing to an enolization reaction (Scheme 21), 3% unreacted ketone could be isolated ... 

There is no -hydrogen atom present in methyl- and neopentylmagnesium halide therefore, no reduction reaction products are observed in their reactions. The highest yield of reduction reaction product was obtained with 2-methyl-1-propylmagnesium bromide, which has one tertiary hydrogen atom on the )9-position. In a footnote, the authors made mention of an unpublished result in which the reaction of diisopropyl ketone with fert-butylmagnesium halide, which has nine primary hydrogens in the )ff-position, yielded 65% of the reduction reaction product. 

A comparison of the results of reactions of n-propylmagnesium bromide and isopropylmagnesium bromide with (substituted) benzophenones [15b] led the authors to some conclusions that are presented in Table 4. 

A preference of 1,4-addition by the alkylmagnesium halide species rather than the dialkylmagnesium species, was observed during the reactions of di-/-propylmagnesium and /-propylmagnesium bromide in diethyl ether with the o-quinol acetate 40 [53]. Between concentrations of 0.06 and 0.24 M in diethyl ether, only 2% of 1,4-addition product 41 was observed with the dialkylmagnesium species. However, at 0.24 M concentration of... 

Problem 8.4 When 1-hexyne was added to a solution of //-propylmagnesium bromide, a gas was evolved. The density of the gas showed that it had a molecular weight of 44. When it was bubbled through aqueous KMn04 or Br2 in CCI4, there was no visible change, (a) What was the gas (b) Write an equation to account for its formation, (c) How could you have predicted such a reaction ... 

In such reactions an olefin is formed from the Grignard reagent. When, however, propylmagnesium bromide is allowed to react with diisopropyl ketone, reduction to the secondary alcohol (63%) is accompanied by normal addition of the Grignard reagent to the carbonyl group with formation of the tertiary alcohol (30%) 185 and if magnesium bromide is added to the reaction mixture the yield of tertiary alcohol is considerably increased (to 65%).185... 

The preparation of iV-ethyH 1 -phenylbutyl)amine by Campbell and his co-workers233 illustrates this type of reaction 7V-Benzylideneethylamine (66.5 g, 0.5 mole) in anhydrous ether (50 ml) is added during 1.5-2 h to propylmagnesium bromide (1 mole) in anhydrous ether (250 ml). The mixture is heated under reflux for some hours, set aside overnight, and poured, for hydrolysis, on ice and hydrochloric acid. 

Cyclic halo ethers also undergo reaction with Grignard reagents. 3-Chloro-tetrahydro-2-propylpyran is formed in 73% yield from 2,3-dichlorotetrahydro-pyran and propylmagnesium bromide.345 In a reaction analogous to the Boord synthesis, compounds of this structure are readily cleaved by sodium to the unsaturated alkanols 345,346... 

The following details for the above-mentioned reaction of dichlorotetra-hydropyran with propylmagnesium bromide illustrate the technique ... 

The reaction of 3-(l,l,3,3-tetramethyl-l,3,2-disilaazolidin-2-yl)propylmagnesium bromide (1) with aromatic nitriles gives 2-aryl-l-pyrrolines, due to intramolecular cyclodehydration of the released amino ketones. 

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