Hydroxy halides, alkylation oxidation

Hydrogenolysis of 4-benzylpiperazine-2,6-diones over palladium-charcoal produced 4-unsubstituted piperazine-2,6-diones in high yield. The amino group in l-phenylpiperazine-2,6-dione underwent alkylation with benzyl chloride and phenacyl bromide, but not with simple alkyl halides (1638). Oxidative dimerizations of piperazine-2,6-diones in nitrobenzene have been studied (1639). 2,6-Bis(hydroxy-imino)piperazine heated with palladium-charcoal in o-dichlorobenzene gave 2,6-diaminopyrazine (465). 

Acidic conditions for hydroxy deiaotection can be avoided if benzyl-type ethers are used as the blocking functions. Hiey can be prepared fiom the alcohols by alkylation with benzyl halide/sodium hydride in DMSO or benzyl halide/silveifl) oxide in DMF (the silver salt does not cause acyl migration as a side... 

Then, we wished to make use of the MW technique in the alkylating esterification of cyclic phosphinic acids such as l-hydroxy-3-phospholene oxides (7 and 8), 1-hydroxy-phospholane oxides (11 and 13), and 1,2,3,4,5,6-hexahydro-phosphinine oxide 15. The cyclic phosphinic acids 7,8,11,13, and 15 were reacted with a series of alkyl halides in the presence of K2CO3 under solvent-free and MW conditions (Scheme 7). It was foxmd that the application of TEBAC was beneficial, when alkyl halides with normal or decreased reactivity, such as ethyl iodide, n-propyl bromide, n-butyl bromide, and isopropyl bromide were the reactants. At the same time, when an alkyl halide with increased reactivity, such as benzyl bromide, was used, tiiere was no need for the catalyst [34,44,45]. 

An alternative route to sulphones utilizes the reaction of the appropriate activated halide with sodium dithionite or sodium hydroxymethanesulphinite [6], This procedure is limited to the preparation of symmetrical dialkyl sulphones and, although as a one-step reaction from the alkyl halide it is superior to the two-step oxidative route from the dialkyl sulphides, the overall yields tend to be moderately low (the best yield of 62% for dibenzyl sulphoxide using sodium dithionite is obtained after 20 hours at 120°C). The mechanism proposed for the reaction of sodium hydroxymethanesulphinite is shown in Scheme 4.20. The reaction is promoted by the addition of base and the best yield is obtained using Aliquat in the presence of potassium carbonate. It is noteworthy, however, that a comparable yield can be obtained in the absence of the catalyst. The reaction of phenacyl halides with sodium hydroxy-methane sulphinite leads to reductive dehalogenation [7]. 

Primary alkyl halides (chlorides, bromides, and iodides) can be oxidized to aldehydes easily and in good yields with dimethyl sulfoxide.311 Tosyl esters of primary alcohols can be similarly converted to aldehydes,312 and epoxides313 give a-hydroxy ketones or aldehydes.314 The reaction with tosyl esters is an indirect way of oxidizing primary alcohols to aldehydes (9-3). This type of oxidation can also be carried out without isolation of an intermediate ester The alcohol is treated with dimethyl sulfoxide, dicyclohexylcarbodiimide (DCC),315 and anhydrous phosphoric acid.316 In this way a primary alcohol can be converted to the aldehyde with no carboxylic acid being produced. 

Cyclohexene oxide and its 3-hydroxy derivatives have been opened regio- and stereospecifically with phosphodiesters. The mechanism of the reaction of oxiranes with sodium dialkyl phosphite and diphenylphosphines has been studied. Cyclopropanecarboxylic acid derivatives have been obtained from substituted oxiranes with triethylphosphonoacetate anion.The mechanism of formation of isomeric alkoxyalkylacetates from oxiranes with alkyl halides and mercuric acetate has been discussed. ... 

Oxidation is one of the major causes of protein degradation and has been widely studied. The side-chains of histidine (His), methionine (Met), cysteine (Cys), tryptophan (Trp) and tyrosine (Tyr) residues in proteins are potential oxidation sites. The reactive oxygen species include singlet oxygen O2, superoxide radical O2, alkyl peroxide ROOH, hydrogen peroxide H2O2, hydroxy radicals (HO or HOO ), and halide complexes (CLO )." The reactivity of these oxidants is ... 

Diketene similarly reacts readily with tributyltin oxide in THF at room temperature47 to give the stannyl 3-stannyloxybut-3-enoate which rearranges to the 2-enolate this enolate will then give an ene reaction with an aldehyde,48 or react with an alkyl halide,49 followed by decarboxylation, providing a route to ketones, enones, and ketoaldehydes. Similar reactions with bromomethyl P- or y-lactones result in the formation of P-hydroxy-y-lactones or y-hydroxy-5-lactones. 

Aromatic nitro groups Aromatic rings N-oxides Alkyl hydrazines Alkyl aldehydes N-methyl derivatives Monoalkenes p-Haloethyl mustards N-Chloroamines Alkyl N-nitrosoamines Alkyl esters of either phosphoric or sulfonic adds Aromatic mono- and dialkylamino groups Aromatic azo groups (because of possible reduction to aromatic amines) Aromatic and aliphatic aziridinyl derivatives Aromatic and aliphatic substituted primary alkyl halides Aromatic amines (including their N-hydroxy derivatives and the derived esters Propriolactones and propriosultones Derivatives of urethane (carbamates) Aliphatic and aromatic epoxides... 

Alkylation of pyrimidinethiones is on the sulfur atom (Scheme 75). Alkyl halides, sulfonates, or sulfates effect the reaction in the presence of a base under mild conditions [Pg.187]

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