Nitrite ester cleavage

The presence of carbon dioxide among the products of the reaction of teff-butyldifluoramine with excess nitric acid is a clear indication that C—C bond cleavage occurred. The nitrate and nitrite esters produced in this experiment were mixtures of various alkyl derivatives, and not solely tert-butyl derivatives as in the other cases where nitrate esters were detected. The relative stability of tritvldifluoramine toward oxidative cleavage is fully in accord with known differences between aromatic and aliphatic systems. 

Similarly, the decomposition of nitrite esters has been the subject of much study " and the complexity of the reaction is due to secondary processes following the initial O-N bond cleavage... 

The reaction of alkoxyl radicals (generated by photolysis of nitrite esters) with phosphites has been exploited in a new synthesis of phosphates of hindered alcohols. Another aspect of this radical reaction which has been investigated, has been an evaluation of the ease of )8-cleavage of axial and... 

Conversion of a nitrite ester to a y-oximino alcohol by photolysis involving the homolytic cleavage of a nitrogen-oxygen bond followed by hydrogen abstraction ... 

The initial observation that menthone reacts with amyl nitrite in the presence of base to give a good yield of an open-chain oximino ester was not expanded for synthetic purposes until Woodward almost forty years later utilized this reaction for the cleavage of a 7-keto-decahydroisoquinoline in the course of his total synthesis of quinine. 

Equations 1-10 illustrate some mild methods that can be used to cleave amides. Equations 1 and 2 indicate the conditions that were used by Woodward and Eschenmoser, respectively, in their synthesis of vitamin B12. Butyl nitrite, nitrosyl chloride, and nitrosonium tetrafluoroborate (NO BF4 ) have also been used to cleave amides. Since only tertiary amides are cleaved by potassium -butoxide (eq. 3), this method can be used to effect selective cleavage of tertiary amides in the presence of primary or secondary amides.(Esters, however, are cleaved by similar conditions.) Photolytic cleavage of nitro amides (eq. 4) is discussed in a review. 

Similarly, the a-methylene group of acetoacetic ester is oximinated by the action of sodium nitrite in glacial acetic acid (63%). Nitrosation of alkylated malonic, acetoacetic, and benzoyl acetic esters with subsequent cleavage affords an excellent synthesis for a-oximino esters, RC(=-NOH)COjC2Hj. A survey of several possible procedures for this conversion has been made." If a /3-keto acid is nitrosated, then the Carboxyl group is lost and an a-oximino ketone is formed, viz.,... 

Conjugate addition of nitroalkanes to a,6-unsaturated carbonyl compounds has been achieved using basic alumina, in the absence of a solvent.36 3-Nitropropanal has been prepared by conjugate addition of nitrite anion to acrolein reduction to 3-nitropropanol was effected with borane-dimethyl sulphide.36 -Nitro-acids and u-nitro-esters have been prepared by ring cleavage of 2-nitrocycloalkanones (Scheme 163).362... 

The cinchona ketones resemble o-diketones in that they enolize very readily. For this reason, freshly prepared solutions of the crystalline ketones exhibit the phenomenon of mutarotation, as the ketone of one configuration is converted, through the enol, to an equilibrium mixture of C.8 epimers. Enol derivatives, such as the benzoyl (LXVI, R = C HiCO) and toluenesulfonyl (LXVI, R = CtHtSO ) esters are readily prepared. The cleavage the ketones by sodium ethoxide and alkyl nitrites (95) has already been mentioned (Section I) here we may point out that the reaction involves the attack of the anion of the enol (LXVI, R = H) on the nitrite, followed by a cleavage reaction (LXVII — LXXI) similar to that which is familiar in the cases of -diketones and /3-keto esters. 

The oxidation of cyclohexanol by concentrated nitric acid is mechanistically complex. A reasonable mechanistic route to the dicarboxyUc acid is given here. The first stage of the oxidation is considered to proceed by a mechanism similar to that found in chromic acid oxidations of alcohols (see Experiment [33]).The reaction here involves the initial formation of a nitrate ester intermediate, which, under the reaction conditions, cleaves by proton abstraction to form the ketone. This reaction is accompanied by reduction of the nitrate to nitrite. The proton transfer may involve a cyclic intramolecular rearrangement during the oxidation-reduction cleavage step. A likely mechanism is outlined below ... 

A copper-catalyzed reaction of ketone 57 with tetrabutylammonium nitrite was reported to afford butyl ester 58 via cleavage of a C-C=0 bond (Eq. (6.12)) [29]. The reaction apparently proceeds through a pathway analogous to the... 

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