Hydroxy ammonium salts

Interestingly, Jacobsen et al. have also reported that addition of a /3-hydroxy ammonium salt to the reaction medium accelerates the isomerization in the presence of an /V-benzylated quinine salt epoxidation of cw-stilbene with (27) gives Zrarax-stilbene oxide with 90% ee as the major product (trans cis= >96 4).109 In 2000, Adam et al. reported that the isomerization ratio was related to the triplet-quintet energy gap of the radical intermediate which was affected by the... 

SYNS ETHANESULFONIC ACID, 2-HYDROXY-, AMMONIUM SALT 2-HYDROXYETHANE-SULFONIC ACID AMMONIUM SALT... 

ETHANESULFONIC ACID, 2-AMINO- see TAG750 FiTHANESULFONIC ACID, 2-HYDROXY-, AMMONIUM SALT see ANLIOO ETHANE, l,l,2,2-TETR/ CHLORO-l,2-DIFLUORO- see TBP050... 

Since free NH2OH is unstable it is usual to prepare it in the form of the hydroxy (ammonium salts, which resemble ammonium salts. A number of methods were proposed but only 5 offer practical methods... 

Synonyms Citric acid, ammonium salt 2-Hydroxy-1,2,3-propanetricarboxylic acid, ammonium salt Propanetricarboxylic acid, 2-hydroxy-, ammonium salt... 

Benzeneamine, N-hydroxy-N-nitroso, ammonium salt Cyclohexane 2,4-D... 

Benzeneamine, N-hydroxy-N-nitroso,ammonium salt Nitrilotrlacetic acid 4,4 -Thiodianiline Ethyl acrylate Butyl acrylate Ethyleneimine (Aziridine) p-Nrtrosodiphenylamine Calcium cyanamide Hydrazine Aldrin... 

A new ionic polymeric polycarbamate was synthesized after steps of polyurethane chemistry using 3-iso-cyanatemethyl-3,5,5-trimethylcyclohexyl isocyanate, 2,5-dimethyl-2,5-dihydroperoxyhexane, 1,6-butanediol, 2,4-tolylenediisocyanate, and N,N -bis(j3-Hydroxy-ethyOpiperazine [27]. Modification of the nitrogen of the piperazine ring into quaternary ammonium salt by treatment with methyliodide gave the MPI high electroconductivity. 

Another application of this method is the stereoselective addition of (7 )-2-hydroxy-l,2,2-triphenylethyl acetate, via the lithium enolate, to propenal (acrolein) which affords mainly the ester 13 (d.r. 92 8). When the acid, obtained in the subsequent alkaline hydrolysis, is converted into the ammonium salt derived from (.S)-l -phenylethylaminc, and the salt recrystallized once, then the amine liberated (/f)-3-hydroxy-4-pentenoic acid is obtained in 41 % yield [relative to the (/ )-acetate] and >99.8% ee82. 

The nitrile-hydrolyzing activity of Ar throb act er spp. NS SC 104 was shown to be resistant to the suppressing effect of a-hydroxy nitriles such as lactonitrile and HMTBN, and accumulated the corresponding a-hydroxy acid ammonium salt at a high concentration [77]. HMTBN (200 him) was added to a suspension of Ar throb act er spp. NSSC 104 cells (4% dew) in phosphate buffer (0.1 m, pH 7.5) and mixed at 30 °C seven more additions of the same amount of HMTBN were added at 1 h intervals, then a further eight additions made at 1.5 h intervals over a total reaction time of 19 h. At completion of the reaction, the concentration of 2-hydroxy-4-methylthiobutyrate... 

The reaction of 5-[2-(iV,./V-dimethylamino)ethyl]-l,2,4-oxadiazole with methyl iodide forms the quaternary ammonium salt 170 (Scheme 22), which undergoes elimination in the presence of base (diisopropylethylamine (DIEA), TEA, l,8-diazabicyclo[4.3.0]undec-7-ene, etc.) to form an intermediate 5-vinyl-l,2,4-oxadiazole 171, which undergoes in situ Michael addition with nucleophiles to furnish the Michael adducts 172. As an example, also shown in Scheme 22, 3-hydroxy-pyrrolidine allows the synthesis of compound 172a in 97% yield. Mesylation followed by deprotonation of the 1,2,4-oxadiazole methylene at C-5 enables Sn2 displacement of the mesylate to give the 5-azabicycloheptyl derivative 173, which is a potent muscarinic agonist <1996JOC3228>. 

M. Horikawa, J. Bush-Petersen, E. J. Corey, Enantioselective Synthesis of P-Hydroxy-a-amino Acid Esters by Adol Coupling Using a Chiral Quaternary Ammonium Salt as Catalyst , Tetrahedron Lett. 1999, 40, 3843-3846. 

One-pot conversions of 2-hydroxy(acylbenzenes) with anhydrides or acid chlorides to produce coumarins [52-54] and flavones [54-58] under mild liquiddiquid or solidtliquid two-phase conditions via a Baker-Venkataraman type reaction (Scheme 6.19) are catalysed by quaternary ammonium salts. 3-Substituted coumarins are produced from salicylaldehyde and malonodinitrile, or substituted acetonitriles, in high yield (>85%) in a one-pot catalysed sequential aldol-type reaction and cycliza-tion in the absence of an added organic solvent [59]. When 2 -hydroxychalcones are reduced under catalytic two-phase conditions with sodium borohydride, 2,4-cis-flavan-4-ols are produced [60] (see Section 11.3). 

A combined -cyclodextrin quatemary ammonium salt catalyst promotes the addition of the trichloromethyl anion to aromatic aldehydes and enhances the yield of the a-hydroxy acid [7],... 

Hydroxy ketones also give primarily syn 1,3-diols when chelates prepared with BC13 are reduced with quaternary ammonium salts of BH4 or BH3CN-.88... 

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