Aminoxy group

Dithionite also is capable of cleaving oxime linkages that are formed as the result of the reaction of an aldehyde and aminoxy group (Pojer, 1979). Thus, crosslinks formed between two proteins or other molecules using this reaction strategy can be specifically broken using sodium dithionite. 

Figure 16.9 The O-ECAT reagent structure contains a DOTA chelating group and a terminal aminoxy group for coupling to aldehyde and ketone sites of oxidation within biological molecules.

One of the limitations of anionic polymerization with respect to preparation of block copolymers is the rather limited range of monomers that can be polymerized anionically to form polymers with well-defined stmctures. One solution to this problem is to utilize anionic polymerization to form a well-defined polymer that is functionalized with an end group that can be used to initiate polymerization via another polymerization method, for example, controlled free-radical polymerization. One such functional group is the aminoxy group which can be used to initiate nitroxide-mediated radical polymerization (NMP). °° PSLi has been reacted with 4-methoxy-2,2,6,6-tetramethylpiperidin-1-oxyl (MTEMPO), a stable nitroxide free radical, in THF at -78 °C as shown in eqn [30]. The mechanism of this functionalization was presumed to occur... 

Pseudopeptide A peptide in which one or more peptide bonds are replaced by other functional groups such as sulfonamides, carbamates, aminoxy groups and so on. 

Muscle relaxant activity is found in the aminoxy-methylnaphthalene structure of nafomine (27). The synthesis proceeds from l-chloromethyl-2-methylnaph-thalene (26), which is reacted with N-carbethoxy-hydroxylamine and base. In this way, the basic nitrogen is protected as the carbamate. Loss of the carbethoxy group either during reaction or on workup affords nafomine (27).10... 

This asymmetric a-aminoxylation can be applied to a wide range of aldehydes (Table 6.1) and six-membered cyclic ketones (Table 6.2). Because of the easy conversion of a-aminoxy moiety to the a-hydroxy group, " operational simplicity, and the... 

Monaharan has developed a versatile synthetic route for the synthesis of 2 -0-[(N, iV-dimethylamino)-oxyethyl] modified purine and pyrimidine nucleoside phosphoramidites (63a-d) to be used as antisense oligonucleotide building blocks. In the syntheses of the purine-based analogues, the (iV, N-dimethylamino)-oxyethyl group was introduced via a 2 -allyloxy nucleoside intermediate, while the pyrimidine-based nucleosides were obtained from the TBDMS-protected 2,2 -anhydro-5-methyluridine via ring opening reaction in the presence of borane and ethylene glycol. The aminoxy derivatives were... 

The ultraviolet absorption band at 219 nm of 4-amino-3 isoxazolidone is a function of the carbonyl group (see Sec. 2.3). This analysis is useful as a measure of purity and is used as a quantitative test for cycloserine in formulations. The dimer (2,5-bis-(aminoxy-methyl-1-3, 6-diketopiperazine) absorbs at 288 nm due to the loss of hydroxylamine when treated with alkali reagent. 

Alternative reagents for the introduction of the Teoc group include 2-(trimethylsilyl)ethyl chloroformate (3 X = Cl), trimethylsilylethyl azidoformate (3 X = Ns), trimethylsilylethyl methoxyvinyl carbonate (4), trimethylsilylethyl 4-nitrophenyl carbonate (5), and the aminoxy carbonates (6). Of these, only the 4-nitrophenyl carbonate (5) is commercially available. The carbonate (5) has been used to block NH groups in amino acids and indoles. ... 

The reaction of desmethyl-a-tocopherol 130 and para[ C]formaldehyde, for example, gave the hydroxy[ C]methyl derivative 131. Hydrogenolytic cleavage of the alcoholic hydroxyl group followed by acylation of the phenolic hydroxyl provided a-[5-methyl- C]-tocopherol (132) in an overall radiochemical yield of 48%. Chloro[ C]methylations are illustrated by the conversion of substrates 133 to 134 with H CHO under the influence of concentrated HCl. Subsequent transformation to [ CJmethyl 135 " and to aminoxy[ C]-methyl 136. the latter obtained through reaction with A-hydroxyphthalimide and... 

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