19925-33-8Relevant academic research and scientific papers
Oxoammonium salt oxidations of alcohols in the presence of pyridine bases
Bobbitt, James M.,Bartelson, Ashley L.,Bailey, William F.,Hamlin, Trevor A.,Kelly, Christopher B.
, p. 1055 - 1067 (2014/03/21)
Oxoammonium salt oxidations (using 4-acetylamino-2,2,6,6- tetramethylpiperidine-1-oxoammonium tetrafluoroborate) of alcohols containing a β-oxygen atom in the presence of pyridine yield dimeric esters, while in the presence of 2,6-lutidine the product is a simple aldehyde. The formation of a betaine between pyridine and an aldehyde is presented to explain this disparity in reactivity. The betaine is oxidized by the oxoammonium salt to give an N-acylpyridinium ion that serves as an acylating agent for ester formation. Steric effects deter the formation of such a betaine with 2,6-disubstituted pyridines. A series of alcohols containing a β-oxygen substituent were oxidized to aldehydes in the presence of 2,6-lutidine, and a short study of the relative reactivity of various alcohols is given. An overall mechanism for oxoammonium cation oxidations is suggested, premised on nucleophilic additions to the oxygen atom of the positively charged nitrogen-oxygen double bond. Possible mechanisms for both dimeric oxidations and simple oxidations are given.
N-heteroarylium Salts in Synthesis, 3 Intramolecular ortho-Acylation of Some N-Heteroaromatic Ring Systems
Anders, Ernst,Boldt, Hans Guenter,Clark, Timothy,Fuchs, Renate,Gassner, Thomas
, p. 279 - 296 (2007/10/02)
The title compounds 17 (prepared by methods A-C) have been reacted with sodium bis(trimethylsilyl)amide (18) in a heterogeneous mixture (-80 deg C, 2-60 h).The ortho-substituted N-heteroaromatic compounds 4 are isolated exclusively after an intramolecular and regiospecific reaction .This method represents the first widely applicable acylation technique for N-heteroaromatic compounds in which the incoming substituent (R1CO) functions as an internal electrophile and in which the formation of isomeric or polyacylated products has not yet been observed.Both experimental and theoretical (MNDO) investigations show that the substitution reaction (5) is primarily determined by the conformational and electronic properties of the deprotonation product 25 , which is formed preferentially.
Labile, non-heterocyclic quaternary ammonium salt/esters as transient derivatives
-
, (2008/06/13)
Labile quaternary ammonium salts of the following formula (I) and (II) are provided: STR1 wherein STR2 represents a tertiary aliphatic amine; wherein STR3 represents an unsaturated amine; wherein R represents a member selected from the group consisting of a hydrogen atom, a C1 -C8 open chain or cyclo alkyl group, a C1 -C8 alkoxyalkyl group, a C1 -C8 acyloxyalkyl group, a C1 -C8 haloalkyl group, a C1 -C8 carboxyalkyl group, a C2 -C8 alkenylphenyl group, an aryl group, and a substituted aryl group, whose substituents are selected from the group consisting of a halogen atom, an O-lower alkyl (C1 -C4) group, an O-acyl group, a nitro group, a carboxyl group, and a carboethoxy group; wherein R1 which may be the same or different, represents any member defined by R above with the proviso that R1 cannot be a hydrogen atom; wherein X is --O-- or --S--; and wherein Y represents a member selected from the group consisting of a halogen atom or any other organic or inorganic monovalent equivalent anion; With the further proviso that STR4 respectively cannot represent trimethylamine and pyridine or quinoline when R represents a hydrogen atom and R1 represents a methyl group or a phenyl group. The compounds described above are characterized by their extreme solubility and resistance to oxidation, dealkylation, and protonation prior to chemical and/or enzymatic hydrolysis. Upon chemical and/or enzymatic hydrolysis, these compounds will "cleave," thus releasing their active constituent or constituents, according to the following general scheme(s): STR5 In other words, the title compounds hydrolyze (chemically or enzymatically) releasing a tertiary amine or unsaturated amine derivative, an aldehyde, a carboxylic acid and a hydrogen halide (HX) per the above reaction scheme.
