Aminoalkyl hydrogen

Rearrangement of an iV-alkylsulphamic acid is known. iV-(2-hydroxyprop-l-yl) sulphamic acid (9) rearranges, on heating to reflux in dry mesitylene, to the corresponding aminoalkyl hydrogen sulphate ester (10) (equation 5)34. 

Ammonolysis of Aminoalkyl Hydrogen Sulfates. Later, in discusdng the replacement of —OH groups, it will be shown that, when hydroxyethane-sulfonic (isethionic) acid is treated with ammonia, taurine is obtained by the preferential replacement of the hydroxyl group. 

By contrast, the —OSO3H groups of aminoalkyl hydrogen sulfates can readily be replaced by reaction with ammonia or amines. The reaction of ethanolamine with aminoethyl hydrogen sulfate thus yields hydroxy-cthyl-ethylenediamine. 

It is clear that some hydrolysis occurs and an excess of mineral alkali is to be avoided. The recovered amino alcohols can, however, be converted readily to the corresponding aminoalkyl hydrogen sulfates for reuse. 

Kinetic studies of the base-catalyzed ring closure of co-aminoalkyl hydrogen sulfates have also been carried out (Table 4). The relative rates reveal an order of 5 > 3 > 4, which is the same as that of the co-halo-alkylamines. These cyclizations, like those of the haloalkylamines, were first order in substrate and zero order in base. Hence the reaction sequence probably occurs as shown in Eq. (3). 

Type B (C—C—N + C—S) Syntheses.—The interaction of aminoalkyl hydrogen sulphates and carbon disulphide in alkaline media provides a most useful route to thiazolidine-2-thiones, which has been applied to the preparation of a further range of examples, e.g. (205). Cyclization occurs most rapidly at pH 5—6, but the linear intermediates (204) are isolable under... 

Photoredox systems involving carbonyl compounds and amines are used in many applications. Carbonyl compounds employed include benzophenone and derivatives, a-diketones [e.g. benzil, cainphoroquinone (85),2W 291 9,10-phenanthrene quinone], and xanthone and coumarin derivatives. The amines are tertiary and must have a-hydrogens [e.g. N,A7-dimethylani 1 ine, Michler s ketone (86)]. The radicals formed are an a-aminoalkyl radical and a ketyl radical. 

The reaction between the photoexcited carbonyl compound and an amine occurs with substantially greater facility than that with most other hydrogen donors. The rate constants for triplet quenching by amines show little dependence on the amine a-C-H bond strength. However, the ability of the amine to release an electron is important.- - This is in keeping with a mechanism of radical generation which involves initial electron (or charge) transfer from the amine to the photoexcited carbonyl compound. Loss of a proton from the resultant complex (exciplex) results in an a-aminoalkyl radical which initiates polymerization. The... 

Scheme 21 summarizes further reactions leading to phosphonic acid analogues of amino acids. Treatment of the nitrone (138 R =Me or Pr ) with a dialkyl hydrogen phosphonate (best as the Li derivative which shows greater diastereoselectivity than the Na or K salts), and subsequent steps involving acidolysis of the oximino compound (139) lead to the free (ot-aminoalkyl)-phosphonic acids (140)(phosphonoalanine, phosphonova1ine). 

Asymmetric hydrogenation of a,fi-unsa turated acids.1 2- Aryl-3-methyl-2-bu-tenoic acids (2) undergo highly stereoselective hydrogenation catalyzed by a complex of rhodium with the chiral (aminoalkyl)ferrocenylphosphine (1), but not with... 

Reaction of hydroxyalkylbiuret derivatives 16 and diethyl carbonate yields 1-(hydroxyalkyl)-133-triazin-2,4,6-triones 17, which lead to the corresponding 1-(carboxyalkyl)-13,5-triazin-2,4,6-triones 18. Triazinones 18 afford 1 1 complexes with a series of aminoalkyl substituted pyrimidine-2,4,6-triamines, which form hydrogen-bonded molecular ribbons <99CEJ381>. 

Hamada, T., Torii, T, Onishi, T, Izawa, K. and Ikariya, T. Asymmetric Transfer Hydrogenation of a-Aminoalkyl-a -Chloromethyl Ketones with Chiral Rh Complexes. J. Org. Chem. 2004, 69, 7391-7394. 

In presence of a stoichiometric quantity of triethylamine, pyruvic acid was hydrogenated by the complex [Rh(cod)(BPPFOH)]+ in an optical yield of 83% to lactic add (equation 55).278 The same ligand has been used to hydrogenate aryl aminoalkyl ketones with optical yields of up to 89% (equation 56).279... 

Photoinduced electron transfer from the amine to C6o to yield a radical ion pair is suggested to be the initial step for the formation of 54a-b. This is followed by deprotonation of the amine cation by the fullerene anion to give an a-aminoalkyl and HC6o radical pain [134], Subsequent combination of the radical pair leads to the final product. Formation of 55 is likely to be initiated by PET from 54b to C6o. This is then followed by successive intermolecular proton transfer, hydrogen abstraction, and ring closure to give l,2-H2C6o and 55 (Scheme 21). 

Leautey, M. Jubault, P. Pannecoucke, X. Quirion, J.-C. Synthesis and evaluation of a broad range of new chiral (aminoalkyl)phos-phane ligands for asymmetric hydrogen-transfer reduction of prochiral ketones. Eur. J. Org. Chem. 2003, 3761-3768. 

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