8-Acetoxy nitriles

R)-Cyanohydrins react with toluenesulfonyl chloride, methanesulfonyl chloride or 4-nitrobenzenesulfonyl chloride without loss of stereochemical purity, and the 2-sulfonyloxy-nitrile reacts with a variety of Sn2 reactions to give a variety of products, such as 2-fluoro nitrile [64], 2-azidonitrile [65] and /V- p h t h a I o yl - p rot e c te d 2-aminonitrile [66], 2-acetoxy nitrile [66], and 2-mercapto nitrile [67]. Hydrogenation of 2-sulfonyloxynitriles with LiAIH4 in good chemical yields and high ee afforded 2-monosubstituted (S)-aziridines [68]. 

It was found that the reaction of 5-acetoxy- and 5-benzoyloxy-2(5//)-furanones 174 with aryl nitrile oxides afforded only one cycloadduct, the condensed isox-azoline 233 (88TL5317). In principle, there are four possible cycloadducts 233 and 234 resulting from the anti approach of the 1,3-dipolarophile to the acetoxy group (with exo configuration of the acetoxy substituent), and two further isomers... 

Examples of polyfunctional carboxylic acids esterified by this method are shown in Table I. Yields are uniformly high, with the exception of those cases (maleic and fumaric acids) where some of the product appears to be lost during work-up as a result of water solubility. Even with carboxylic acids containing a second functional group (e.g., amide, nitrile) which can readily react with the oxonium salt, the more nucleophilic carboxylate anion is preferentially alkylated. The examples described in detail above illustrate the esterification of an acid containing a labile acetoxy group, which would not survive other procedures such as the traditional Fischer esterification. 

Otera et al. extended the tin-mediated allylation to 2-substituted allyl bromides.80 When 2-bromo and 2-acetoxy-3-bromo-l-propene were used, the allylation with tin produced the corresponding functionalized coupling products (Eqs. 8.36 and 8.37). In the case of 2,3-dibromopropene, the reaction occurred exclusively through allylation in the presence of the vinyl bromo group. The presence of other electrophiles such as a nitrile (-CN) or an ester (-COOR) did not interfere with the reaction. 

The stereoselective synthesis of the 12-acetoxy enone 428, related to the limonoid azadiradione, has been achieved in 12 steps (16% overall yield), starting from tricyclic diester 429. The key steps involve an intramolecular 1,3-dipolar cycloaddition of a nitrile oxide and a Stille coupling reaction of vinyl iodide with stannylfuran (469). 

Acyl nitronates (63) derived from primary AN are characterized by two types of such transformations the rearrangement into a-acetoxy aldoximes (219) and elimination of the corresponding carboxylic acids to form nitrile oxides (Scheme 3.63). 

A rule stating that nitriles with an acetoxy group on the right of carbon atom 2 are dextrorotatory was formulated by Deulofeu, and although it applies to most acetylated nitriles, some exceptions have been found. Propionylated nitriles are liquids or solids that can be molec-ularly distilled without decomposition. Benzoylated nitriles are all solids. 

In the presence of tetrakis(triphenylphosphine)palladium a-cyano allylic acetates rearrange to y-acetoxy-a,/3-unsaturated nitriles. The products can he converted into furanc derivatives (equation II).2... 

Acylation of RMnI (10, 290).1 Acylating agents such as acyl halides and anhydrides react with RMnI to form ketones in high yield. This reaction can be used to provide acetoxy ketones, keto esters, keto nitriles, and diketones in generally high yield. 

Nucleophilic substitution reactions with a-acetoxy-ji.y-unsaturated nitriles. 5 This reaction can he effected with Pd(0) as catalyst it proceeds regioselectively with rearrangement to give "/-substituted- ./l-unsaluratcd nitriles. 

An iron-catalyzed multicomponent reaction of aldehyde 4a, acetophenone, acetyl chloride and acetonitrile, which was used as the solvent, gave P-amino ketones such as 32 (Scheme 8.11) [41]. It was assumed that the sequence starts with an aldol reaction of aldehyde and ketone and then proceeds further with a displacement of a P-acetoxy group by the nucleophilic nitrile-nitrogen. 

Ketosulfoxides, which are intermediates in the alkylation of ester by Li-CH2 SOCH3, are cleaved to ketones (Eq. (234) ) 5 21K Analogously, the acetoxy group has been reductively removed from a-acetoxylated nitriles 522 ... 

Using tetrafluoroboric acid, several unsaturated acids and nitriles were thus made reactive and were converted into acetoxy lactones [3]. Tosyloxy-, phosphoryloxy-and iodomethyl lactones as well as cyclic ethers resulting from analogous neighbouring group participation will be discussed in connection with other hypervalent iodine reagents. 

Bernsteinsaure 3-Acetoxy-2-diazo- -l-ethylester-4-nitril El4b, 1105 (Amin + NaN02)... 

Pentansanre 4-Acetoxy-2-chlor-4-methyl- -nitril E19a, 802 (R-HgX + En)... 

Butansaure 4-(2-trani--Methoxy-cyclohexyl)- -nitril E19a, 822 (Cyclopropan/HgX2 + En) 1-Buten 3-Acetoxy-2-piperidino-E15/1, 628 (R-CO-O-CHR —C = CH + Amin)... 

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