112741-73-8Relevant academic research and scientific papers
An improved synthesis of optically pure 4-Boc-5,6-diphenylmorpholin-2-one and 4-Cbz-5,6-diphenylmorpholin-2-one
Dastlik, Kim A.,Sundermeier, Uta,Johns, Deidre M.,Chen, Yuyin,Williams, Robert M.
, p. 693 - 696 (2007/10/03)
A convenient synthesis of optically pure 4-Boc-5,6-diphenylmorpholin-2-one and 4-Cbz-5,6-diphenylmorpholin-2-one by reaction of (+)- or (-)-2-amino-1,2-diphenylethanol with ethyl bromoacetate, followed by N-protection, and p-TsOH-mediated ring-closure is
Diastereoselective intermolecular radical addition to nitrones
Ueda, Masafumi,Miyabe, Hideto,Teramachi, Masako,Miyata, Okiko,Naito, Takeaki
, p. 6653 - 6660 (2007/10/03)
The intermolecular radical addition to chiral nitrones 2, 4, 5, and 16 was studied. The isopropyl radical addition to Oppolzer's camphorsultam derivative 2 of glyoxylic nitrone proceeded with excellent diastereoselectivity to give the desired isopropylated product 3a accompanied by the diisopropylated product 3b. A high degree of stereocontrol in the reaction of cyclic nitrone 4 was achieved. The ethyl radical addition to nitrone 4 with triethylborane afforded the desired ethylated product 9a accompanied by the diethylated product 10a and the ethylated nitrone 11a. To evaluate the utility of cyclic nitrone 4, several alkyl radicals were employed in the addition reaction, which afforded the alkylated products 9b-d with excellent diastereoselectivities. In the presence of Mg(ClCO4)2, the ethyl radical addition to BIGN 16 afforded selectively syn isomers. In contrast, the alkyl radical addition to 16 took place even in the absence of Lewis acid to give anti isomers.
Practical Asymmetric Syntheses of α-Amino Acids through Carbon-Carbon Bond Constructions on Electrophilic Glycine Templates
Williams, Robert M.,Sinclair, Peter J.,Zhai, Dongguan,Chen, Daimo
, p. 1547 - 1557 (2007/10/02)
The optically active D- and L-erythro-4-(benzyloxycarbonyl)-5,6-diphenyl-2,3,5,6-tetrahydro-4H-1,4-oxazin-2-ones (3) and D- and L-erythro-4-(tert-butoxycarbonyl)-5,6-diphenyl-2,3,5,6-tetrahydro-4H-1,4-oxazin-2-ones (3) can be efficiently brominated to serve as electrophilic glycine templates for the asymmetric synthesis of amino acids.It was found that coupling to these templates can proceed with either net retention or net inversion of stereochemistry.The final deblocking to the amino acids is accomplished with either dissolving-metal reduction or catalytic hydrogenolysis.The syntheses of β-ethyl aspartic acid, norvaline, allylglycine, alanine, norleucine, homophenylalanine, p-methoxyhomophenylalanine, cyclopentylglycine, and cyclopentenylglycine and a formal synthesis of clavalanine are described.In addition, the direct asymmetric syntheses of N-t-BOC-allylglycine and N-t-BOC-cyclopentenylglycine are described.
