Direct lactonization of α-amino γ,δ-unsaturated carboxylic acid esters via olefin activation: stereo- and regioselective production of homoserine lactone scaffolds having contiguous stereocenters

Properties of Calcium Acetate Manufactured with Etching Waste Solution and Limestone Sludge as a Cementitious High-Early-Strength Admixture

“…Some examples of carboxylic acids include acetic acid, formic acid, gluconic acid, and propionic acid. Hence, it was confirmed that RAA contained carboxylic acid groups [27].…”

From racemic precursors to fully stereocontrolled products: one-pot synthesis of chiral α-amino lactones and lactams

“…5, 155.7, 154.9, 139.4, 129.0, 128.9, 128.7, 125.9, 125.8, 83.5, 82.5, 81.5, 58.7, 31.1, 29.9, 28.3 Di-tert-butyl 1-((3R,5S)-2-oxo-5-phenyl-1-tosylpyrrolidin-3-yl)hydrazine-1,2-dicarboxylate (4p) was obtained as a white solid (59 mg, 36% yield by cat. 3i) in two steps; mp = 84-85 °C; TLC: R f = 0.20 (petroleum ether/EtOAc = 6 : 1 v/v); 1 H NMR (500 MHz, CDCl 3 ) δ 7.51 2H),3H),2H),2H),6.31 (s,1H),5.44 (d,J = 8.4 Hz,1H),5.36 (d,J = 63.1 Hz,1H),2.65 (ddd,J = 31.1,19.1,9.1 Hz, 1H), 2.38 (s, 3H), 2.32 (dd, J = 12.2, 5.7 Hz, 1H), 1.42 (d, J = 26.8 Hz, 18H) ppm; 13 C NMR (125 MHz, CDCl 3 ) δ 170. 3, 155.7, 154.7, 145.5, 139.7, 135.2, 129.4, 129.1, 128.8, 128.4, 126.2, 82.8, 81.8, 60.1, 58.4, 53.7, 32.6, 28.2, 21.9 Di-tert-butyl 1-((3R,5R)-2-oxo-5-phenyl-1-tosylpyrrolidin-3yl)hydrazine-1,2-dicarboxylate (5p) was obtained as a white solid (57 mg, 35% yield by cat.…”

“…Indeed, among the documented examples, a stepwise process is generally involved in the formation of all chiral centers on the ring system of lactones or lactams, and relies mainly on the application of enzymatic resolution, 5 chiral auxiliaries, 6 or chiral starting materials. 7 In addition, most cases still suffered from several related drawbacks, including low efficiency, 8 costly transition metal catalysis, 9 or scope restrictions. 10 Accordingly, the development of new, flexible, and expedient protocols for the preparation of these valuable heterocycles is of significant importance.…”

Tin powder‐promoted oxidation/allylation of glycine esters: Synthesis ofγ,δ‐unsaturatedα‐amino acid esters

“…[ 4 ] In addition, the γ , δ ‐unsaturated α ‐amino acid esters are also important building blocks for synthesis of α ‐methylene‐ γ ‐butyrolactone or pyrrolidine compounds, which are core units in numerous natural products. [ 5 ] As a consequence, practical and efficient approaches to obtain γ,δ ‐unsaturated α ‐amino acids and their esters have been paid much attentions. At present time, γ , δ ‐unsaturated α ‐amino acid esters are mainly synthesized by the nucleophilic addition of imine with allyl reagents such as allyltributyltin or allyltrichlorosilane [ 6 ] ; electrophilic coupling or addition [ 7 ] of amino acid derivatives with allyl halides or allyl carbonates; and radical coupling [ 8 ] of α ‐bromoglycine esters with allyltributyltin.…”