Acetals nucleophilic substitution reaction

What product would you expect to obtain from a nucleophilic substitution reaction of (S)-2-bromohexane with acetate ion, CH3CO2- Assume that inversion of configuration occurs, and show the stereochemistry of both reactant and product. 

Sulfoximines bearing a chiral sulfur atom have recently emerged as valuable ligands for metal-catalysed asymmetric synthesis.In particular, C2-symmetric bis(sulfoximines), such as those depicted in Scheme 1.51, were applied to the test reaction, achieving enantioselectivities of up to 93% ee. The most selective ligand (R = c-Pent, R = Ph) of the series was also applied to the nucleophilic substitution reaction of l,3-diphenyl-2-propenyl acetate with substituted malonates, such as acetamido-derived diethylmalonate, which provided the corresponding product in 89% yield and 98% ee. 

Acetyl chloride must always be stored under anhydrous conditions, because it readily reacts with moisture and becomes hydrolysed to acetic acid. On the other hand, if one wanted to convert ethyl chloride into ethanol, this nucleophilic substitution reaction would require hydroxide, with its negative charge a better nucleophile than water, and an elevated temperature (see Section 6.3.2). It is clear, therefore, that the carbonyl group is responsible for the increased reactivity, and we must implicate... 

Bonds typically hydrolyzed include carboxylic and phosphoric esters, amides, acetals, amidines, as well as metal ion complexes. (When a nucleophilic substitution reaction uses the solvent as the nucleophile, the reaction is often referred to as solvolysis.)... 

Esters are formed in nucleophilic substitution reactions in which the nucleophile is a carboxylate anion. The anions of carboxylic acids are relatively weak nucleophiles towards sp3-hybridized carbon. Swain s nucleophilic constant, n, for acetate ion is 2.7183, slightly smaller than that for chloride. Thus acetate is selectively alkylated by alkyl halides in aqueous solution, e.g. 

In contrast with the relatively facile nucleophilic substitution reactions at the 2-position of the indole system, only 3-iodoindole has been reported to react with silver acetate in acetic acid to yield 3-acetoxyindole (59JOC117). This reaction is of added interest as 3-iodo-2-methylindole fails to react with moist silver oxide (72HC(25-2)127). It is also noteworthy that the activated halogen of ethyl 3-bromo-4-ethyl-2-formylpyrrole-5-carboxylate is not displaced during the silver oxide oxidation of the formyl group to the carboxylic acid (57AC(R)167>. 

On the other hand, when 39 was heated with hydrogen bromide in acetic acid, 1,2-di-<9-acetyl-( 1,3/2,6)-3,4-dibromo-6-(bromomethyl)-l,2-cyclohexanediol (50) was obtained, which was converted into 1,2-di-0-acetyl-( 1,3/2)-3(bromomethyl)-5-cyclo-hexene-l,2-diol (51) by debromination with zinc dust in glacial acetic acid [21]. Hydro-xylation of 51 with osmium tetroxide, and successive acetylation yielded 1,2,3,4-tetra-C>-acetyl-6-bromo-6-deoxy-pseudo-a-DL-glucopyranose (52). Nucleophilic substitution reactions of 52 with sodium acetate gave pseudo-a-DL-glucopyranose pentaacetate (55), which gave pseudo-a-DL-glucopyranose (54) by usual hydrolysis [22]. Alternatively, the pentaacetate 55 was obtained as a minor component in a poor yield by nucleophilic substitutions of 2,3,4-tri-0-acetyl-l,6-dibromo-l,6-dideoxy-pseudo-... 

Since sulfonation of pyridine iV-oxide is about as difficult as is that of pyridine itself and takes place at the 3-position,17 it has been assumed18 that, in fuming sulfuric acid, pyridine iV-oxide reacts only in the salt form (3), when the prediction is that substitution at C-3 would take place. It is, however, difficult to account for the fact that bromination, even at 110° in the presence of iron powder, does not occur.17 Bromination in chloroform solution in the presence of acetic anhydride and sodium acetate (when the O-acetate is the the probable substrate) take place readily, however, to give 3,5-dibromopyridine JV-oxide.19 The predicted order of nucleophilic reactivity, on the basis of both atom localization energies and ground-state v-electron density calculations, is 4 > 2 > 3. The same order is predicted for the nucleophilic substitution reactions of the salts of pyridine JV-oxide. In actual practice, iV-alkoxypyridinium derivatives undergo nucleophilic attack preferentially at C-2.20-23 The reaction of some pyridine iV-oxides with phosphorus pentachloride may involve the formation... 

Methylsulfonyl)-3-phenyl-3//-l,2,3-triazol[4,5-d]pyrimidine 176 was prepared by the reaction of 175 with sodium methyl sulfide, followed by oxidation with potassium permanganate in acetic acid. A nucleophilic substitution reaction on 176 with potassium cyanide gave 182, but the same reaction did not take place on 175. Treatment of 176 with sodium methoxide... 

The fact that the rate law depends only on the concentration of tert-butyl chloride means that only tert-butyl chloride is present in the transition state that determines the rate of the reaction. There must be more than one step in the mechanism because the acetate ion must not be involved until after the step with this transition state. Because only one molecule pert-butyl chloride) is present in the step involving the transition state that determines the rate of the reaction, this step is said to be unimolecular. The reaction is therefore described as a unimolecular nucleophilic substitution reaction, or an SN1 reaction. 

These findings can be rationalised by consideration of a common intermediate. An intermediate carbinolamine could undergo either a nucleophilic substitution reaction, probably through an ionisation step facilitated by the high temperature and by assistance from the nitrogen lone pair to form the spiro compound in dimethylacetamide, or the intermediate may suffer dehydration in apolar solvents to form the corresponding isatin-3-imine. This imine can undergo facile syn-anti isomerisation upon protonation in acetic acid and thus yields the indoloquinoxaline derivative... 

As discussed at the beginning of Sect. 4.1, a masked carbonyl, such as acetal, is more suitable for macrocyclization than the carbonyl itself b ause the nucleophilic substitution reaction on the former is irreversible. Overman and coworkers [111] developed a C—C bond-forming cyclization approach to 8-membered ethers by Lewis acid-promoted alkene substitution of mixed acetals. Thus, oxocenes with... 

A similar approach was described by Kim et al. <01MI1403> to build the Furstner synthon from the vinylogous amide 9, previously described, and the commercially available dimethyl aminomalonate hydrochloride as building block for pyrrole systems. The cyclocondensation reaction between the vinylogous amide 9 and dimethyl aminomalonate hydrochloride was performed in acetic acid at room temperature to yield the presumed Intermediate 12 via an acid-catalyzed nucleophilic substitution reaction. The mixture was then diluted with additional acetic acid and heated under reflux to facilitate the intramolecular ring closure and the loss of the methoxycarbonyl moiety to produce the desired pyrrole. Formation of lamellarin O dimethyl ether was achieved as in the Furstner approach <95JOC6637>. 

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