Synthesis of α-[²H]-amines via photodecarboxylation of N-phthaloyl α-amino acids

Synthesis of Medium‐ and Large‐Ring Compounds Initiated by Photochemical Decarboxylation of ω‐Phthalimidoalkanoates

“…We have investigated these reactions in the last years [l] taking advantage of the well-studied and synthetically easily accessible phthalimido chromophore [2]. The alkyl-substituted amino acids such as valine, leucine, isoleucine, or tevt-leucine always had to be transformed into the corresponding esters prior to photolysis, otherwise efficient decarboxylation was observed [3]. In contrast to the chain-modification steps (isomerization, cyclization, ring enlargement4)), this a-decarboxylation proceeds from the first excited singlet state as well as from the triplet state with relatively high quantum yields.…”

“…An advantageous aspect of this reaction is its regioselectivity: COOH groups at other positions of the molecule were completely stable under the photolysis conditions. Thus, N-phthaloylglutamic or N-phthaloylaspartic acid were transformed into the corresponding p-and y-amino acids, respectively [3]. Even prolonged irradiation of these products did not lead to further decarboxylation, i.e., the 'remote' COOH groups were completely inert.…”

Spin-Selectivity in Photochemistry: A Tool for Organic Synthesis

“…This effect was indeed found in the photochemisty of N-phthaloyl α-amino acids when the decarboxylation was coupled with deuteration at the C α -carbon. 80 This reaction most probably proceeds via a carbanion reaction similar to the N-phthaloyl glycine and Ntrimethylsilylmethyl phthalimide photolyses investigated recently by Mariano and Yoon. 81 Numerous applications are obvious for the decarboxylative photocyclization if the protonation step could be efficiently suppressed.…”

Synthesis and Modifications of Amino Acids and Peptides via Diradicals

“…Thus, upon irradiation of N-phthaloyl amino acids, a photodecarboxylation takes place which is initiated by a hydrogen abstraction from the carboxyl group [21]. Some years later, this method was developed further by Griesbeck to a very straightforward synthesis of a-monodeuterated primary amines starting with N-phthaloyl a-amino acids [22]. To the same group a very versatile cyclization method is owed, which is based on the irradiation of the potassium salts of N-phthaloyl amino acids in an acetone/water mixture.…”