39739-05-4Relevant articles and documents
Intramolecular carbenoid ylide forming reactions of 2-diazo-3-keto-4- phthalimidocarboxylic esters derived from methionine and cysteine
Enssle, Marc,Buck, Stefan,Werz, Roland,Maas, Gerhard
body text, p. 433 - 440 (2012/05/20)
Methionine, S-benzylcysteine and S-allylcysteine were converted into 2-diazo-3-oxo-4-phthalimidocarboxylic esters 8a-c in three steps. Upon rhodium-catalysed dediazoniation, two intramolecular carbenoid reactions competed, namely the formation of a cyclic sulfonium ylide and that of a six-ring carbonyl ylide. The S-methyl and S-benzyl ylides 12a and b could be isolated, while S-allyl ylide 12c underwent a [2,3]-sigmatropic rearrangement. The short-lived carbonyl ylides derived from methionine and S-benzylcysteine formed head-to-tail dimers by a [3 + 3]-cycloaddition and could be trapped with external dipolarophiles, while the S-allyl derivative 14c yielded the pentacyclic compound 17 by an intramolecular [3 + 2]-cycloaddition reaction.
Photochemical transformations of proteinogenic and non-proteinogenic amino acids
Griesbeck, Axel G.
, p. 272 - 283 (2007/10/03)
The photochemistry of N-activated enantiomerically pure α-amino acids is described with emphasis on chemo-, regio-, stereo-, and spin selectivity. An especially valuable chromophore is the phthalimido group. The first excited singlet states are short-lived and deactivated (chemically) via homolytic CH cleavage or (physically) via electron-transfer steps. The first excited triplet states are chemically deactivated via electron-transfer reactions and subsequent deprotonation/coupling steps. A wide variety of product types were synthesized, and potential target molecules were available by tuning the reaction conditions. Also remote groups can be activated by means of electron-transfer steps, which represents an attractive new synthetic protocol for macrocyclization.
Straightforward synthesis of optically pure methyl (S)-2-phthalimido-4-oxobutanoate and some of its acetal and thioacetal derivatives
Meffre,Durand,Le Goffic
, p. 1111 - 1114 (2007/10/02)
An improved procedure for the synthesis of optically pure methyl (S)-2-phthalimido-4-oxobutanoate (3a) and some of its acetal and thioacetal derivatives 4, 5 and 7 from cheap commercially available L-methionine methyl ester hydrochloride (1a) is described.
Photochemistry of N-phthaloyl derivatives of methionine
Griesbeck, Axel G.,Mauder, Harald,Mueller, Ingrid,Peters, Eva-Maria,Peters, Karl,Von Schnering, Hans Georg
, p. 453 - 456 (2007/10/02)
Photocarboxylation of N-phthaloyl derivatives of methionine sulfoxide 1b and methionine sulfone 1c was observed in acetone as the major reaction. For 1a a fast electron transfer initiated cyclization which leads to the bicyclization product 3 (X-ray structure)was observed in the sensitized photolysis. Direct photolysis of 1a leads preferentially to the tricylic product 4 and the decarboxylation product 5. The methionine methyl ester 6a-c showed electon transfer initiated cyclization (for 6a) and disproportionation (for 6b), whereas 6c proved to be photostable.
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-
Photodecarboxylation of N-Phthaloyl-α-amino Acids
Sato, Yasuhiko,Nakai, Hideo,Mizoguchi, Tomishige,Kawanishi, Masazumi,Hatanaka, Yasumaru,Kanaoka, Yuichi
, p. 1263 - 1270 (2007/10/02)
N-Phthaloylglycine (1a) was irradiated with a high pressure mercury lamp to give N-methylphthalimide (2a) in an excellent yield.N-Phthaloyl derivatives 1b-k of other α-amino acids also afforded the decarboxylated products 2b-k.In the cases of N-phthaloylserine (11) and di-phthloylcystine (1m), N-vinylphthalimide (3) was isolated as a major product.On the other hand, N-phthaloylmethionine (11a) and methyl N-phthaloylmethionate (11b) were treated in the same manner to give the aza-thiacyclo-heptanol derivatives 12a-b having a new ring system.Solvent effects and possible pathways of these reactions were examined.Keywords- N-phthaloyl-α-amino acid; photolysis; decarboxylation; cyclization; efficiency; solvent effect; υ-hydrogen abstraction
