58073-26-0Relevant academic research and scientific papers
Synthesis of new amides based on N-Phthaloyl-α-Amino Acids
Tukhtaev,Yusupov,Vinogradova
, p. 3049 - 3058 (2021/05/28)
N-phthaloyl derivatives of aliphatic α-amino acids were synthesized using phthalanhydride under standard conditions. The optimization reaction carried out by the thermal method to obtain the amides of these N-phthaloyl amino acids resulted in transimitted rather than amidation. The target amides of N-phthaloyl-α-amino acids were obtained by acylation of the amine with the corresponding acid chloroanhydrides in dichloromethane. These results were compared with the results of a similar acylation in a non-polar solvent (benzene). The dependence of the direction of the reaction on the duration of the acylation and the amount of amine used was established. The conditions for the formation of the corresponding N-phthaloyl-α-amino acid amides and asymmetric phthalic acid diamides were found. It is noteworthy that the formation of diamides is directly proportional to the equivalent amount of amine and the duration of the reaction, which makes it possible to purposefully control the synthesis in one reactor.
General Access to Modified α-Amino Acids by Bioinspired Stereoselective γ-C?H Bond Lactonization
Vicens, Laia,Bietti, Massimo,Costas, Miquel
supporting information, p. 4740 - 4746 (2020/12/25)
α-Amino acids represent a valuable class of natural products employed as building blocks in biological and chemical synthesis. Because of the limited number of natural amino acids available, and of their widespread application in proteomics, diagnosis, drug delivery and catalysis, there is an increasing demand for the development of procedures for the preparation of modified analogues. Herein, we show that the use of bioinspired manganese catalysts and H2O2 under mild conditions, provides access to modified α-amino acids via γ-C?H bond lactonization. The system can efficiently target 1°, 2° and 3° γ-C?H bonds of α-substituted and achiral α,α-disubstituted α-amino acids with outstanding site-selectivity, good to excellent diastereoselectivity and (where applicable) enantioselectivity. This methodology may be considered alternative to well-established organometallic procedures.
Photochemistry of N-Phthaloyl α-Amino Acid Esters: A New Approach to β,γ-Unsaturated α-Amino Acid, Dihydrobenzazepinedione, and Pyrrolizidinone Derivatives
Griesbeck, Axel G.,Mauder, Harald,Mueller, Ingrid
, p. 2467 - 2476 (2007/10/02)
The N-phthaloyl-α-amino acid methyl esters of 2-aminobutyric acid (2a), valine (2b), norvaline (2c), tert-leucine (2d), isoleucine (2e), allo-isoleucine (2f), leucine (2g), methionine (2h), alanine (2i), and phenylalanine (2k) were synthesized in enantiomerically pure form via the N-phthaloyl-α-amino acids (1a-k), and their photochemistry was studied.Except 2i and 2k, which proved to be photostable, all compounds were converted into three types of products, depending on the substitution pattern: a) isomerization products (derivatives of β,γ-unsaturated α-amino acids) 3a, b, c, and e, b) ring expansion products (benzazepinedione esters) 4a and c, and c) cyclization products (5d from the tert-leucine derivative 2d).High diastereoselectivities (d.r. >95:5) were observed for all reactions except the transformations of the 2-aminobutyric acid derivative 2a.The absolute configuration of the α-stereogenic center was retained during photolysis, as proven for the isodehydrovaline (type a product) 3b.PCC oxidation (to give 7b) and hydrogenation afforded 2b with an optical rotation comparable to the starting material.Treatment of 3b with an acid or a base led to epimerization (3b') or isomerization of the C=C bond (6b), respectively.The diastereomeric dihydrobenzazepinedione esters 4a, b were formed with d.r. = 33:67 (cis:trans) and in 60percent yield during photolysis of 2a.The isoleucine derivative 2e, however, was converted into the cis isomer 4a with high diastereoselectivity (d.r. >95:5), whereas the corresponding allo substrate 2f was only converted into the trans-isomer 4b.Ethylene was extruded during irradiation of the latter substrates and during irradiation of the norvaline derivative 2c, whereas propene extrusion from the leucine derivative 2g led to the formation of the unsubstituted type b product 4c.The methionine derivative 1h was the only N-phthaloylamino acid which did not show photodecarboxylation, instead two ξ-hydrogen abstraction products were formed: the hydroxy acid 9h and the tetracylic lactone 10h.The methionine ester 2h was only converted into the ring expansion products 11h, h' presumably by a photo electron transfer step.The chronology of the double hydrogen transfer reaction (γ- followed by δ-H abstraction, leading to type a products) was determined by using the deuterium labeled compound (+/-)-2b.Key Words: Photochemistry / α-Amino acids / Amino acids, β,γ-unsaturated / Photoisomerization / Benzazepinedione esters / Selectivity, enantio-, diastereo-
