J. Am. Chem. Soc. 1997, 119, 3665-3669
3665
Optical Activity of Oxo Amide Crystals
†
†
,†
‡
Toru Asahi, Makoto Nakamura, Jinzo Kobayashi,* Fumio Toda, and
Hisakazu Miyamoto‡
Contribution from the Kagami Memorial Laboratory for Materials Science and Technology,
Waseda UniVersity, 2-8-26, Nishi-Waseda, Shinjuku-ku, Tokyo 169, Japan, and
the Department of Applied Chemistry, Faculty of Engineering, Ehime UniVersity,
Matsuyama, Ehime 790, Japan
X
ReceiVed June 14, 1996
Abstract: It has been known that oxo amide crystals made up of achiral molecules can be photochemically converted
into optically active â-lactams by irradiation with a high pressure mercury lamp. Although the oxo amide crystal
belongs to an enantiomorphic class D2, its optical activity could not be detected so far. We successfully measured
the components of the gyration tensor of the oxo amide crystal by using the HAUP (high accuracy universal
-
4
-4
-4
polarimeter) method: g11 ) -3.5 × 10 (-79°/mm), g22 ) -1.4 × 10 (-32°/mm), g33 ) -3.0 × 10 (-68°/
mm) at 305 K, where the optical rotatory powers are indicated in parentheses. It has been proved by direct experiments
that the optical activity of the reactant and the product in this reaction system remains unchanged over the
photocyclization process.
Introduction
Scheme 1
1
Optical activity (OA) of a noncentrosymmetrical molecule
takes place when the displacement of some electron in the
molecule is restricted to a helical path under the inhomogeneous
electromagnetic field. Such a constraint to the helical path is
caused by vicinal actions among the neighboring atoms in the
2
molecule. It becomes possible from the same reason that a
crystal made up of achiral molecules becomes optically active
when the degree of freedom of molecules, e.g., rotation and
orientation about chemical bonds, are severely restricted by
forming a crystalline lattice. Quartz and diacetyl phenolphtha-
lein are typical examples, their crystalline states being optically
active but immediately loosing OA in liquid solutions.
diisopropylglyoxylamide and the corresponding â-lactams were
successfully determined.
7
2
As there were no ways to determine OA of 1 crystal by using
5
the existing methods, we identified crystals of 1, which gave
Among optically active crystals composed of achiral mol-
ecules some crystals can be used as starting materials for
2
-crystals with (+) and (-) signs of OA in solutions, as (+)-
and (-)-1 respectively. However this identification is essentially
tentative and presupposes that OA remains unchanged between
the reactant and the product over the photochemical conversion.
To be more general, such indeterminacy of OA of solids has
been a long unresolved problem, which prevented accurate
elucidation of the solid state asymmetric syntheses. We8
developed the HAUP (high accuracy universal polarimeter)
method, which enables us to measure simultaneously OA and
birefringence ∆n of crystals belonging to any systems. We
applied the HAUP method to 1 crystals in order to investigate
the above mentioned reaction more accurately.
3,4
absolute asymmetric synthesis of useful chemicals.
us (F.T)5 successfully obtained optically active â-lactams
-hydroxy-1-isopropyl-4,4-dimethyl-3-phenyl-azetidin-2-one (2),
One of
3
important antibiotics, by photocyclizations of optically active
crystals of achiral oxo amide N,N-diisopropylphenylglyoxyl-
amide (1) (Scheme 1). The space groups of both 1 and 2
-10
6
crystals were established by X-ray structure analyses as equally
4
2
enantiomorphic D , which permits OA of both signs. Al-
though the optical rotatory power of a solution of 2 was
measured, e.g., [R]D ) +123° (c 0.5 in CHCl3), OA of both
crystals could not really be measured so far due to the presence
of birefringence. Determinations of the absolute configurations
of the structures of the reactant and the product were too difficult
to be made, although recently those of m-chlorophenyl-N,N-
HAUP Measurement of Optical Activity
5
1 crystals grown from benzene solution were vitreous prisms,
where (010) terrace planes were well developed. They were
subjected to HAUP measurements. According to Weissenberg
photographs of (-) and (+) specimens, the same lattice
constants, say, a ) 12.802 (12.794) Å, b ) 13.896 (13.902) Å,
and c ) 7.487 (7.506) Å, were obtained. They were in good
†
Waseda University.
Ehime University.
Abstract published in AdVance ACS Abstracts, April 1, 1997.
‡
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(
(
(
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