Breaking the Symmetry of Axially Chiral N‐Aryl‐2(1H)‐pyrimidinones by Spontaneous Crystallization

Making Use of the Direct Process Residue: Synthesis of Bifunctional Monosilanes

“…First, dynamic crystallization was performed by the solvent evaporation method. [8][9][10] Each spiro compound (1-3)w as dissolved in methanol and crystallized by evaporating the solventw ith stirring at room temperature. The solid-state circular dichroism (CD) spectrumo ft he resulting crystal was measured to analyze whether it converged preferentially to any optically active substance.W hen the crystallization was repeateds everal times, 2 and 3 consistently formed only ar acemic mixture, but 1 converged on one of the enantiomorphic crystals.…”

“…[5] Valuable successful examples have been reportedf or amino acid derivatives, [6] pharmaceutical materials, [7] and axially chiral materials. [8] Dynamic crystallization through racemizationb yr ing-opening and ring-closing processes has been reported as as uccessful method for asymmetrica mplification of isoindolinones [9] and pyrrolinones [10] having an aminal chiral center,b ut there are no reports of asymmetricamplification reactions by racemization of spirocyclic ring systems such as spiropyrans.…”

Deracemization of Axially Chiral Nicotinamides by Dynamic Salt Formation with Enantiopure Dibenzoyltartaric Acid (DBTA)

“…Spontaneous resolution by crystallization is a powerful tool for obtaining optically active axially chiral materials [34][35][36][37][38][39]; we recently reported a new example of spontaneous chiral symmetry breaking of an axially chiral nicotinamide, obtaining the product in up to 94% enantiomeric excess (Scheme 1) [40]. The nicotinamide shown in Scheme 1 afforded a conglomerate, and each enantiomer formed enantiomorphic crystals.…”

Asymmetric Synthesis of an Amino Acid Derivative from Achiral Aroyl Acrylamide by Reversible Michael Addition and Preferential Crystallization

“…[4] Pioneering work in dynamic preferential crystallizationu sing racemic conglomerate crystals was reported by Havinga. [5] Furthermore, many exampleso fa xially chiral materials, [6] amino acids, [7] and pharmaceutical materials [8,9] were found to provide single-handed molecules selectively.H ere, we report the development of an ew absolute asymmetrics ynthesis involving ac ombined methodologyt o generate chiral centers from achiral materialsw ith deracemization by dynamic crystallization.Recently,a na symmetric transformation of achiral meso-2,3diphenylsuccinimides to the chiral trans-isomers followed by dynamicp referential crystallization was demonstrated in high ees under absolutely achiral conditions. [10] Furthermore, aza-Michael additiont oa ne none leading to an optically activea minoketone [11] and Strecker reaction [12] werea lso reported by deracemization involvingd ynamic crystallization.…”

“…[4] Pioneering work in dynamic preferential crystallizationu sing racemic conglomerate crystals was reported by Havinga. [5] Furthermore, many exampleso fa xially chiral materials, [6] amino acids, [7] and pharmaceutical materials [8,9] were found to provide single-handed molecules selectively.H ere, we report the development of an ew absolute asymmetrics ynthesis involving ac ombined methodologyt o generate chiral centers from achiral materialsw ith deracemization by dynamic crystallization.…”