Amino ether product

Nitraminothiazoles are sufficiently acidic to be alkylated by diazomethane the methyl substituent is introduced on the exocyclic nitrogen (194). When sulfathiazole is methylated with diazomethane in ether, a mixture of ring-methylated and amino-methylated products is obtained, the ratio being 30 70 (85). With anion 31 (R = p-NO CsH4SO -) the ratio becomes 15 85 (195). 

Several functional groups containing carbon-nitrogen double bonds can participate in radical cyclizations. Among these are oxime ethers, imines, and hydrazones.337 Hydrazones and oximes are somewhat more reactive than imines, evidently because the adjacent substituents can stabilize the radical center at nitrogen.338 Cyclization at these functional groups leads to amino- substituted products. 

In a soluble polymer strategy comparable to resin-capture [145], Janda reported a MeO-PEGsooo-supported dialkyl borane reagent (31) that was used in the purification of a solution-phase library of y9-amino alcohols [146]. Purification was achieved by simply adding (31) to the crude reaction mixture followed by subsequent precipitation of the polymer with diethyl ether to give polymer-supported 1,3,2-oxazaboroU-dine (32) (Scheme 5.2). The /9-amino alcohol product could then be released from the soluble support by treatment with acid. In a two-step synthetic strategy that is readily amendable to automation, the isolation of a small library of /9-amino alcohols was accomplished with all compounds obtained in >80% purity. 

Intermolecular addition and addition-cyclization reactions of aminium cation radicals with electron-rich alkenes such as ethyl vinyl ether (EVE) allow an entry into products containing the N—C—C—O moiety of 13-amino ethers 70 or the equivalent of /3-amino aldehydes 71. The mild conditions under which aminium cation radicals are generated from PTOC carbamates makes the reactions described in Scheme 22 possible. In the absence of hydrogen atom donors, the /3-amino ethoxy(2-pyridylthio) acetal 71 was the major product. The mixed acetal can easily be converted... 

On the other hand, an effective synthesis of P-aminotetralins including an asymmetric electrophilic animation by dialkylazodicarboxylates was reported by the same authors [44]. a-Tetralones 85 were transformed into chiral imines 86 using various enantiomerically pure amino ethers. The imines were treated with DTB AD or DBAD to afford the aminated products 87 which are the precursors of the non racemic P-aminotetralins 88 (Scheme 40 Table 3.7). 

This modification resulted in a yield improvement for the pentacyclization process from 47 % to 66 %. Treatment of the amino ether 192 with diisobutylaluminum hydride in refluxing toluene accomplished Eschenmoser-Grob fragmentation and reduction of the initially formed immonium ion, to give the unsaturated amino alcohol 193 in 86% yield. It was gratifying to find that 193 was the only product formed in this reaction. In the tetrahydropyran derivative, reduction of 192 to 193 is accompanied by about 15 % simple elimination. Displacement of the tosyl group in 196 gives sulfide 197, which is oxidized to sulfone 198. This material is metallated and coupled with enantiomerically pure aldehyde to secure the codaphniphylline skelton [74]. 

A related problem is elimination in ester enolates with leaving groups in the -position. Knight and coworkers observed virtually no a-allyl- -amino acid product in the Ireland silyl ester enolate rearrangement of phthalate (213 Scheme 41). Rearrangement of the -methoxycarbonyl analog (214), however, provided methyl ester (215) in a 79 21 mixture of stereoisomers after treatment with etheral diazomethane. 

Amino ethers (either free, or preferably cationized) have a broad range of current and potential applications in paper manufacturing as coatings and sizes that improve paper strength, retention of pigments and dyes, the production of conductive coatings, textile finishes, and other uses,597.i689,2311,2316,2317,2320,2328,2332,... 

Reactions of crotyl organometallics with aldimines can give linear (4) and/or branched (5) homoallyl-amines, a result of addition at the a- and y-crotyl carbon atoms (equation 1). Although branched products usually dominate, the metal (M) and the imine substituents (R and R ) can strongly influence the regiochemical outcome of the reaction similar effects are observed with crotyl in additions to iminium salts and gem-amino ethers. 

Entry R gem-Amino ether (133) R R3 Yield of products (136) (%) MgBr AlyiBr Ref... 

As mentioned previously, there are many Mannich-type cyclizations of acetals that undoubtedly occur via enol ether intermediates and afford -amino acetal products. A prototypical example is presented in Scheme 12. In this sequence, due to Wenkert, the iminium ion precursor is formed by semihydrogenation of a nicotinic ester salt. ... 

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