Acetonitrile Ritter reaction

Attempts to replace the phenylsulfenyl group in 1239 with benzyloxytrimethyl-silane 13 c leads, via fragmentation of 1240 and 1241 and incorporation of acetonitrile in a Ritter reaction, to 82% of a 7 1 mixture of 1242 and 1243 [44]... 

The I2 addition to 3 in chlorinated solvents yields a mixture of isomeric 2,6-diiodobicy-clo[3.3.0]octanes (endo.exo-69 and endo,endo-7tt) (equation 71)22. When the reaction was carried out in aqueous acetonitrile under similar conditions, the formation of a mixture of acetamido derivatives 71 and 72, arising from iodocyclization followed by the capture of the iodonium ion by the solvent to give a Ritter reaction intermediate, accompanied the formation of products 69 and 70 (equation 72)22. 

Controlled potential electrolysis (cpe) of alkanes in acetonitrile/0.1 M TBABF4 yields acetamidoalkanes (Table 3). Voltammetry and coulometry indicate a 2e-oxidation to a carbenium ion that subsequently reacts with the nitrogen atom of acetonitrile in a Ritter reaction (Eq. 6) [20]. 

By analogy with their behavior in mass spectrometry, branched hydrocarbons are cleaved when oxidized in CH3 CN/TEABF4 at —45 °C. The resulting acetamides of the fragments (Table 6) are formed by cleavage of the initial radical cation at the C,C bond between the secondary and tertiary C atom, to afford after a second electron transfer, carbocations, which react in a Ritter reaction with acetonitrile [29]. 

The Ritter reaction [6] proceeds by the electrooxidation of alkyl iodides (56) in an MeCN-(Pt) system to form Ai-alkyl acetamides (58) (Scheme 21). Attack of carbenium ion intermediate - from dissociation of the initially formed alkyl cation radical - to acetonitrile would give the iminium cation (57). However, a different mechanism is proposed, whereby the alkyl iodide reacts with the electrogenerated iodo cation [I]" " [73]. 

Amantadine Amantadine, 1-adamantanamine (10.1.12), is synthesized from adaman-tane. It is directly brominated to 1-bromadamantane (10.1.10), which in Ritter reaction conditions when heated with a mixture of acetonitrile and concentrated sulfuric acid transforms into 1-acetylaminoadamantane (10.1.11). Hydrolysis of this product using alkali leads to the formation of amantadine (10.1.12) [16,17]. 

Amantadine Amantadine, 1-adamantylamine (36.1.3), is synthesized from adamantane, which is first brominated with molecular bromine to make 1-bromoadamantane (36.1.1). Interacting this with acetonitrile in a Ritter reaction conditions gives 1-acetylaminoadaman-tane (36.1.2). Hydrolysis of the last with sodium hydroxide gives amantadine [1-6]. 

Several procedures have been reported using acetonitrile as solvent for Bi(III) salt-catalyzed transformations involving epoxides as substrates [54, 93-95]. However, no reference has been made about the occurrence of the Ritter reaction, even... 

Scheme 20 Ritter reaction of 5 3,6fS-epoxysteroids with acetonitrile, catalyzed by BiBr3...

DFT calculations on the Mg(L—H)(L) complex reveal how water and acetonitrile can be lost (Scheme 9). Thus intramolecular proton transfer tautomerizes the neutral acetamide ligand in 48 into the hydroxyrmine form in 49, which can then dissociate via another intramolecular proton transfer to yield the four-coordinate adduct 50, which now contains both water and acetonitrile ligands. It is this complex that is the direct precursor to water and acetonitrile loss. Note that the reaction shown in Scheme 9 is a retro-Ritter reaction and involves fragmentation of the neutral rather than the anionic acetamide ligand, which is a bidentate spectator ligand. 

In the mechanistic outline to Scheme 2, the intermediate oxocarbenium ion was trapped by an oxygen nucleophile to give an O-glycoside. Further experimentation has revealed that Af-nucleophiles can also be applied, leading to Af-glycosyl products [26]. Thus, if the reactions are carried out in the presence of acetonitrile, a Ritter reaction ensues affording nitrilium ion 49 (Scheme 12). This relatively unstable intermediate can be trapped... 

Hydroxysulfenylation. Hydroxysulfenylation of cyclohexene is possible with diphenyl disulfide in CH2C12—TFA under air in the absence of a metal salt, but the reaction requires several days at 25°. With Pb(OAc)4 reaction occurs in 30 minutes at 0°. Actually Mn30(0Ac)7 is as efficient as Pb(OAc)4, particularly in reactions with dibenzyl disulfide. The trifluoroacetoxy sulfides can be converted into acetamido sulfides by reaction with acetonitrile containing cone. H2S04 (Ritter reaction, equation I).1... 

Acetonitrile with 3-alkyl(or aryl)-3-hydroxyquinuclidines (125) under Ritter reaction conditions has been used to prepare 3-acetamido-3-alkyl(aryl)quinuclidines (129). 

Ritter reaction of the triene 287 in triflic acid, performed to accomplish the synthesis of a marine sesquiterpene, gave the product acetamide derivative via a predominant trans antiparallel addition of H+ and acetonitrile to the endocyclic double bond920 [Eq. (5.343)]. 

Nafion-H has also been shown to be active in the Ritter reaction. Treatment of alcohols, such as benzyl alcohols, 1-adamantanol [Eq. (5.346)], and 2-norborneols with acetonitrile or benzonitrile in the presence of Nafion-H under forcing conditions (140-145°C, 18—48h), affords the corresponding carboxamides in moderate to excellent yields (40-99%).652 Nafion-H can be reused after a simple activation (washing with deionized water and acetone followed by drying at 105°C). 

Tertiary hydroxyls can undergo several reactions under acidic conditions to form artifacts in degradation experiments. In acidic acetonitrile/ water solutions, primary, secondary and tertiary alcohols can undergo a Ritter reaction to form amides (Fig. 83). 

Figure 83 Ritter reaction of tertiary alcohols to form amides under acidic conditions in acetonitrile.

The formation of IN-benzhydrylacetamide from benzhydrol and acetonitrile constitutes a Ritter reaction (11) which, in this case, is accomplished under extraordinarily mTld, and above all neutral conditions. Usually, such reactions are carried out in... 

Alkyl iodides are cleaved in acetonitrile/lithium perchlorate to iodine and al-kyl.cations. These react prior to or after rearrangement in a Ritter reaction with acetonitrile to form N-alkylacetamides in 21% to 75%yield (Eq. (217) ) 4S8). 

An unusual compound (18) was reported by Lora-Tamayo et al.23 This they obtained from acetonitrile and 2,3-dimethylbutadiene, the only conjugated diene studied thus far. They presumed it arose via two Ritter reactions and a Diels-Alder reaction as shown below. 

It was suggested73 that the most probable mechanism of this reaction is an initial aldol condensation of the starting ketone leading to the a,/ -unsaturated ketone 100 or to the /Miydroxyketone 101 which serve as precursors to the tertiary carbenium ions 102, which reacts in turn with nitriles by an acid-catalyzed Ritter reaction to give 103 (equation 36). This suggestion is confirmed by the results of a cross-reaction experiment of benzaldehyde and diethyl malonate with acetonitrile to give 14 (equation 37). 

However, only recently the acid-catalyzed reaction of the keto and cyano functional groups have been reported. In these articles the unreactivity of ketones in the Ritter reaction was noted and the search for conditions to overcome this lack of reactivity was described. The reactions of camphor 110a81, isocamphanone 110b82 and their structural analogs isofenchone 110c and 5-exo-ethyl norcamphor 110d83 with acetonitrile in the... 

A combination of the Pummerer rearrangement and the Ritter reaction occurs in the reaction of acetonitrile with methyl phenyl sulfoxide (equation 25) in a mixture of irifluoroacetic acid and its anhydride, although a substantial amount of the nonnal a-acetoxylation also occurs. Participation by amido groups is also possible, the interest here being largely in the construction of lactams via the intramolecular cycli-zation mode. Whereas Wolfe and his coworkers were unable to find conditions for the cyclization of S-phenylcysteinamide sulfoxides under Pummerer conditions, Kaneko found that variously substituted... 

In its utilization of acetonitrile, the oxazoline synthesis shown in Scheme 56 resembles a Ritter reaction.The procedure is convenient, but yields are variable the pyrolysis gives starting alkene plus acetamide as by-products. Another oxazoline synthesis and subsequent conversion to a cif-amino alcohol is discussed later (Scheme 85). A recent y-hydroxy-a-amino acid synthesis incorporates the following type of transformation (Scheme 57).If a three-day equilibration with anhydrous HBr was introduced iMtween stages i and ii, almost pure trans product was obtained. The paper has many usefol references. Yet another modified Ritter reaction is shown in Scheme 58. ... 

If the reactions are carried out in a nitrile as solvent, rather than dichloromethane, using triflic acid as catalyst, a modified Ritter reaction takes place, and the intermediate nitrilium ion traps the liberated amine, forming an amidine (Scheme 67). In an earlier reaction cf. Scheme 67) the lithium perchlorate catalyzed reaction of sulfenyl chlorides with alkenes in the presence of nitriles had also given l-amido-2-sulfenyl adducts. Ritter products are also obtained in good yields by anodic oxidation (Pt or C, 1.2-1.4 V) of disulfides in acetonitrile, in the presence of excess alkene, using B114NBF4 as supporting electrolyte (Scheme 68). ... 

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