American Chemical Society
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Chiral Arrangement of N-Ethyl-N-isopropylphenylglyoxylamide Molecule in Its Own Crystal and in an Inclusion Crystal with a Host Compound and Their Photoreactions in the Solid State That Give Optically Active β-Lactam Derivatives. X-ray Analytical and CD Spectral Studies

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journal contribution
posted on 1997-12-26, 00:00 authored by Fumio Toda, Hisakazu Miyamoto, Hideko Koshima, Zofia Urbanczyk-Lipkowska
N-Ethyl-N-isopropylphenylglyoxylamide (3c) forms chiral crystal in which its achiral molecules are arranged in a chiral form, and the chirality in the crystal was identified by measurement of the CD spectrum in Nujol mull. Generation of the chirality occurs by twisting of the CO−CO bond of 3c in the crystal. Photoirradiation of the chiral crystal of 3c in the solid state gave optically active β-lactam derivative (4c) of 80% ee. By X-ray analysis, absolute configurations of the chiral crystal and 4c were elucidated. The achiral molecules of 3c are also arranged in chiral forms in inclusion complexes with chiral hosts such as (R,R)-(−)-trans-2,3-bis(hydroxydiphenylmethyl)-1,4-dioxaspiro[4.4]nonane (5a), (R,R)-(−)-trans-2,3-bis(hydroxydiphenylmethyl)-1,4-dioxaspiro[5.4]decane (5b), and their (S,S)-(+)-enantiomers, 6a and 6b, respectively. The crystal structure of a 1:1 inclusion complex of 3c with 5b (7b) was analyzed. Photoirradiation of 7b in the solid state gave (R)-(+)-4c of 85% ee. Photochemical conversions of some other derivatives of 3c to the corresponding β-lactams were also studied. Interestingly, however, irradiation of the 1:1 inclusion complex of N,N-dimethylglyoxylamide (3a) with 5a, which had been prepared by mixing both components in the absence of solvent, gave (R)-(+)-β-lactam (9a) of 45% ee, although the 1:1 complex that had been prepared by recrystallization of the components from toluene gave (S)-(−)-9a of 100% ee. Mixing of powdered chiral (−)-3c crystal with a 2:1 inclusion complex of 5b and MeOH gave a new 1:1 complex of 5b and chiral (+)-3c. The inversion of the chirality of 3c in the solid state was studied by continuous measurements of CD spectra in Nujol mulls.