Amines alkoxyamine

Table 5. Addition of Organolithium Reagents R2Li to Oxime Ethers 4 and Reduction of the Resulting Alkoxyamines 5 to Amines 6"...

Functional alkoxyamines used as initiators for NMP include 283-287. The functional alkoxyamines can be formed in situ by use of a functional azo compound or peroxide. NMP has been shown to be compatible with hydroxy, epoxy, amide and tertiary amine groups in the initiator. Carboxylic acid groups can cause problems but may be tolerated in some circumstances.106... 

Like Af-alkoxy-Af-chloroamides, the S 2 reactivity of A-acyloxy-A-alkoxyamides is directly analogons to the 8 2 reactions of a-haloketones where the a-carbonyl groups are well known to enhance 8 2 reactivity Although there are no comparative rate data for reactions of amines or alkoxyamines, these arguments shonld apply to snbstimtion at the amide nitrogen in A-acyloxy-A-alkoxyamides. 

Table 32 Cyclization of Amines and N-Alkoxyamines to 2,6-Disubstituted Piperidine Derivatives (Equation 114)...

The oxidation of amines, acylhydrazines, and alkoxy amines described in this section involves the formation of nitrenes or other intermediates, depending on the nature of the nitrogen substituent and the oxidant, although lead tetraacetate is commonly employed. For example, a nitrenium ion or an amino lead derivative was proposed as the intermediate in the oxidation of alkoxyamines with lead tetraacetate 2. However, evidence has been provided that the jV-acetoxy species is the intermediate in the aziridination of alkenes with V-aminophthal-imide and /V-aminoquinazolinone, where a mechanism analogous to the Bartlett mechanism for the peracid epoxidation of alkenes should be operating3,4. 

Treatment of benzaldehyde oxime ether (166) with butyllithium (pentane/-10 C) demonstrates the complexity of the reaction (Scheme 32) as the desired alkoxyamine (167 R = Bu) is accompanied by other oxime-derived side products" (entry 1, Table 12). Selectivity is reagent/solvent dependent as allyl Grignard (ether)," allylzinc bromide (THF)," and butyllithium (THF)" treatment produce predominantly amine (171 R = allyl) (the Beckmann rearrangement derived product), alkoxyamine (167 R = allyl) (the oxime addition product) and ketone (169 R = Bu) (the nitrile-derived pro ct), respectively (entries 2-4, Table 12). 

HALS hardly absorb UV light but act most likely as radical scavengers and hydroperoxide decomposers. Chemical structures are mainly based on piperidines. Sterically hindered piperazines are known as well (Fig. 11.15). Secondary amines are the most common structures, but alkyl-amines or, more recently, alkoxyamines are commercially... 

Polystyrene prepared by NMP has been reacted with thiuram disulfide compounds (i.e., tetraethyl thiuram disrrUrde and N,N -diethyl-bis[2-(ttimethylsilyl)oxyethyl] thiuram disulfide) to form the corresponding tertiary amine-functionalized polymers. Characterization of the fimrtionalized polymers by MALDl is difficult due to the labile nature of the C-S bond at the chain end, thus ESI was used to demonstrate the high functionality of the resulting polymers. More recently, Favier and co-workers ° have developed a method to convert macro-alkoxyamines to maao-RAFT agents allowing for the preparation of novel block copolymers. 

NOR HALS (alkoxyamine hindered amine stabilisers) are the latest products for stabilising agricultmal films. They have very low basicity, with low pKa values of aroimd 4.6 compared with the 7 to 10 typical of many more basic HALS. This makes them much less likely to lose efficiency by reacting with the acidic derivatives of agrochemicals. 

NOR HALS alkoxyamine hindered amine light stabilisers... 

Another class of low interactivity HALS is that based on NOR (alkoxyamine hindered amines) chemistry. These are also low basicity HALS which are claimed to provide stabilization efficiency and chemical resistance. Low MW products of this type, such as bis-(l-octyloxy-2,2,6,6,tetramethyl-4-piperidinyl) sebacate... 

Examples of additives are the following EA = iodonium salt, e.g. diphenyliodonium hexafluorophosphate (more rarely, a sulfonium salt) and related derivatives [113], alkyl halide, e.g. phenacyl bromide [1.14] and triazine, e.g. 2,4,6-tris(trichloromethyl)-l,3,5-triazine ED = borate disulfide, group IVb dimetal [1.15] HD = alcohol, THE, thiol, benzoxazine, aldehyde, acetal, silane (e.g. tris(trime1hylsilyl)silane = (TMS)3Si-H) [1.16]), germane, borane, stannane, alkoxyamine, silyloxyamine, polymer substrate, etc. EPD = amine [1.17], thiol, etc. The generated radicals (e.g. Ph, R, RsSi, RR C R R in [1.13]-[1.17] ) are the initiating species. Efficient novel or newly modified dye structures in the Dye/amine, Dye/iodonium salt or Dye/silane two-component PISs have been proposed within the last 4 years (see section 1.3.5). 

NOR-HALS (Alkoxyamine Hindered Light Stabilizers) represent a new generation of sterically hindered amines. Thanks to their low basicity and high chemical resistance, they disrupt radically initiated processes faster than standard HALS stabilizers [527]. 

NFSi has been used as a versatile oxidant in reactions that involve a Pd(II)/Pd(IV) catalytic cycle. The oxidative addition of NFSi to Pd(II), which generates a reactive Pd(IV) species is the first step in the functionalization of a Pd-C bond as exam-plified in the arylation of a Pd(II)-alkyl complex (eq 56). Depending on the reaction conditions, a competition between di-amination (see section NFSi as an amination reagent) and car-boamination exists. In the presence of an alcohol as solvent, a palladium-catalyzed alkoxyamination is observed with use of NFSi as oxidant. ... 

The nitroxide-mediated homopolymerization of AA under its nonprotected form was performed in 1,4-dioxane solution at 120 ° C and was initiated by an SG1 -based alkoxyamine. The results showed a good control over the polymerization and the chain-end structure toward moderate molar mass poly-mers. °° ° When high molar masses were targeted, chain transfer to the solvent and to the polymer had a nonnegligible effect on the structural quality. Those living PAA macroalkoxy-amines found applications in the synthesis of amphiphilic diblock copolymers, either in solution or in aqueous emul-sion. ° ° They were also employed as stabilizers/ compatibilizers of carbon nanotubes/polymer composites. ... 

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