Efficient chiral crystallization and asymmetric synthesis via a solid-state di-.pi.-methane-type photorearrangement

5.06 Di-π-methane, Oxa-di-π-methane, and Aza-di-π-methane Photoisomerization

“…When such crystals are irradiated, two asymmetric di-p-methane isomerizations take place (Scheme 3, Table 1). 25 The enantioselectivity is induced by the chiral environment in the crystal and depends on the irradiation time, the conversation, and the reaction temperature. The same reaction, but without any chiral induction, was observed in solution.…”

Absolute asymmetrische Synthese: Ursprung, Beeinflussung und Verstärkung von Chiralität

“…Dies wird einer zunehmenden Unordnung in der Kristallpackung zugeschrieben, was auf die Anreicherung des Produkts und das lokale Schmelzen der Kristalle durch überschüssige Strahlungsenergie zurückgeführt wird. [112] Es wurde jedoch nach 20% Umsatz kein Schmelzen beobachtet, was zu den relativ hohen ee-Werten führte.…”

Solid-State Photochemistry of o-Aroylbenzothioates: Absolute Asymmetric Phthalide Formation Involving 1,4-Aryl Migration

“…[1][2][3] Of particular interest in this context is the "absolute" asymmetric transformations which are influenced only by the chiral crystalline environment without any external chiral source in the starting compounds. [4][5][6][7][8][9] This situation arises when compounds crystallized by spontaneous resolution undergo reactions in the crystalline lattices yielding new stereocenters in the products. Since the solid-state reaction proceeds with least atomic or molecular movement, the X-ray crystallographic approach is very useful for investigation of the mechanistic features and reactivities.…”