Memory of chirality generated by spontaneous crystallization and asymmetric synthesis using the frozen chirality.
Asymmetric synthesis using frozen chirality generated by spontaneous crystallization was performed. Achiral asymmetrically substituted imide with a tetrahydronaphthyl group on the nitrogen atom crystallized in a chiral fashion, with space group P2(1)2(1)2(1). The molecular chirality generated by spontaneous crystallization was retained in cold THF. The half-life determined on the basis of decreasing optical activity followed by CD spectrometer was 7.8, 33.1, and 150.0 min at -20, -30, -40 degrees C, respectively. The energy barrier (DeltaG()) of racemization was calculated with the temperature dependence of the kinetic constant to be 18.24-18.36 kcal mol(-)(1) at 233-253 K. The memorized frozen chirality was transferred to permanent optically active alcohols by nucleophilic addition with n-buthyllithium.
Sakamoto
Masami
M
Department of Materials Technology, Faculty of Engineering, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan. sakamotom@faculty.chiba-u.ac.jp
Iwamoto
Takuya
T
Nono
Naoyuki
N
Ando
Masaru
M
Arai
Wataru
W
Mino
Takashi
T
Fujita
Tsutomu
T