Stereo-divergent synthesis of L-threo- and L-erythro-[2,3-2H2]amino acids using optically active dioxopiperazine as a chiral template

Stereoselective synthesis of L‐[2,3,4,5‐D4] ornithine

“…We previously reported the stereoselective synthesis of l-threo-and l-erythro-[2,3-D 2 ]amino acids by an asymmetric deuteration of dehydroamino acids prepared by condensation of aldehydes with a novel chiral glycine template 1 (Scheme 1). 3,4 Production of the desired [2,3,4,5-D 4 ]ornithine may be feasible if an appropriately deuterium-labeled 3-aminopropanal is available. As shown in Scheme 2, we adopted an optically active butenolide 2, easily prepared from l-glutamic acid, as the starting material.…”

“…We have recently explored the methods for stereoselective isotopic substitution of only one of the diastereotopic methyl groups and methylene protons of amino acid side-chains. [3][4][5][6][7][8][9][10][11] However, investigation of long-chain amino acids, such as lysine or arginine, remains untouched despite their importance in protein function. In this paper we disclose the first example of [2,3,4,5-D 4 ]ornithine, in which all the diastereotopic methylene protons are stereoselectively labeled with deuterium.…”

Transannular Rearrangement of Activated Lactams: Stereoselective Synthesis of Substituted Pyrrolidine‐2,4‐diones from Diketopiperazines

“…In the synthesis of coronamic acid, BernabØ and coworkers reported the opening of a mono-Boc-substituted derivative of a Pro-containing DKP by alkaline hydrolysis, [22] whereas Nishiyama and co-workers described a modified Sasaki reaction in which a bis-Boc-DKP was alkylidenated with an aldehyde in the presence of potassium tert-butoxide with concomitant cleavage of one of the two protecting groups. [23] We made the unexpected observation that instead of displaying conventional protecting-group behavior, the two Boc moieties on the nitrogen atoms of the heterocycle reacted under certain basic conditions as electron-withdrawing activators to promote the unusual transformation of bis-BocDKPs 1 into the corresponding 3-aminopyrrolidine-2,4-dione derivatives 2 and/or 3 ( Table 1 and Table 2). …”

Diastereoselective Hydrogenation in the Preparation of Fine Chemicals

“…Palladium on charcoal was used most frequently as the catalyst and the resulting diastereoselectivity varied from 20 to 90%. Deuteration experiments with substituted diketopiperazine (R1 ¼ 1-methyl-ethyl, R2 ¼ phenyl, R3 ¼ H) with different protecting groups (R4 and R5) showed that the presence and type of the protecting group strongly influence the stereoselectivity of the reaction and that the diastereomeric excess can be reversed when a different protecting group is used [35].…”

“…Greater success was achieved by modifying dehydro-amino acids with a natural amino acid to give a rigid cyclic diketopiperazine structure (1b, figure 1). The diastereoselective hydrogenation of unsaturated diketopiperazine derivatives, which correspond to the cyclic ,-dehydrodipeptides (1b), has been studied by several groups [34][35][36][37][38][39][40][41][42][43], with the aim of developing a general method for the stereoselective synthesis of -amino acids. The chiral information was usually introduced by means of a natural amino acid and (S)-proline was often used to advantage as a chiral auxiliary (1c, figure 1).…”