- Synthesis of (5R)-4-methyl-5-phenyl-1,3,4-oxadiazinan-2-one and some N-acyl derivatives from (R)-phenylglycine
-
(5R)-4-Methyl-5-phenyl-1,3,4-oxadiazinan-2-one was synthesized from (R)-phenylglycine in five steps and in 65% overall yield. In addition, a convenient and practical method for N-acylation of 1,3,4-oxadiazinan-2-one directly with acids in the presence of
- Rodrigues, Alessandro,Olivato, Paulo Roberto,Rittner, Roberto
-
p. 2578 - 2582
(2007/10/03)
-
- A New Approach to Asymmetric Synthesis of Polycycles on the Basis of o-Quinodimethane Generation
-
The fluoride anion induced 1,4-elimination of 2-phenyl>-3,3-dimethyloxazolidinium salts generates (E,E)-α-alkyl-α'--o-quinodimethane intermediates, which are trapped stereoselectively with dienophiles to give polycycles.Intramolecular cyclization of 2-phenyl>-3,3-dimethyl-4-(R)-methyl-5(R)-phenyloxazolidinium triflate at 0 deg C produces a 3:1 diastereoisomeric mixture of 6--trans-octahydrophenanthrene, which is converted by hydrogenolysis on Pd/C to trans-octahydrophenanthrene with D +46.6 deg (50percent ee).Similarly, intramolecular cyclization of 2-phenyl>-3,3-dimethyl-4(S)-methoxymethyl-5(S)-phenyloxazolidinium triflate produces, after hydrogenolysis on Pd/C, trans-octahydrophenanthrene with D -51.1 deg (55percent ee).The enantioselection in the cycloaddition with o-quinodimethane intermediate may be accounted for on the basis of ?-stacking interaction in the Diels-Alder transition state.
- Ito, Yoshihiko,Amino, Yusuke,Nakatsuka, Masashi,Saegusa, Takeo
-
p. 1586 - 1590
(2007/10/02)
-