321174-88-3Relevant academic research and scientific papers
Intermolecular 1,3-dipolar cycloaddition of chiral and geometry fixed α-alkoxycarbonylnitrone, 5,6-dihydro-5-phenyl-2H-1,4-oxazin-2-one N-oxide
Tamura, Osamu,Gotanda, Kentoku,Terashima, Romi,Kikuchi, Mayumi,Miyawaki, Tsutomu,Sakamoto, Masanori
, p. 1861 - 1862 (1996)
The 1,3-dipolar cycloaddition of (R)-5,6-dihydro-5-phenyl-2H-1,4-oxazin-2-one N-oxide[(5R)-2], a chiral and geometry fixed α-alkoxycarbonylnitrone, with alkenes 3-6 proceeded smoothly to afford cycloadducts 7-10 as main products via β-exo mode.
Design, synthesis, and 1,3-dipolar cycloaddition of (5R)- [and (5S)]-5,6-dihydro-5-phenyl-2H-1,4-oxazin-2-one N-oxides as chiral (E)-geometry-fixed α-alkoxycarbonylnitrones
Tamura,Gotanda,Yoshino,Morita,Terashima,Kikuchi,Miyawaki,Mita,Yamashita,Ishibashi,Sakamoto
, p. 8544 - 8551 (2007/10/03)
Optically pure (5R)- [and (5S)]-5,6-dihydro-5-phenyl-2H-1,4-oxazin-2-one N-oxides [(5R)- and (5S)-2] were designed as chiral (E)-geometry-fixed α-alkoxycarbonylnitrones 1. The nitrones (5R)- and (5S)-2 were synthesized by three-step oxidation of (R)- and (S)-phenylglycinols [(R)- and (S)-3], condensation of the resulting (R)- and (S)-2-hydroxylamino-2-phenylethanols [(R)- and (S)-5] with glyoxylic acid, and cyclization of the intermediary nitrones (R)- and (S)-6b. The nitrone (5R)-2 reacted with olefins 7-14 under mild conditions to afford the corresponding cycloadducts 15-22 as the main products via the least sterically demanding exo modes. Cycloadduct 30 obtained from (5S)-2 and cyclopentadiene was effectively elaborated to (1S,4S,5R)-4-benzyloxycarbonylamino-2-oxabicyclo[3.3.0]oct-7-en-3-one (28), the key synthetic intermediate of carbocyclic polyoxin C.
