Generation and amplification of optical activity of axially chiral N-(1-naphthyl)-2(1H)-pyrimidinethione by crystallization

Abstract

X-Ray crystallographic analysis of N-(1-naphthyl)-2(1H)-pyrimidinethione revealed that the space group was tetragonal and chiral P4(3). The rate of racemization due to the C-N bond rotation was considerably influenced by the solvent properties. A nonpolar solvent lowers the ΔG(‡)value by about 3.0 kcal mol(-1) relative to the value in a polar or a protic solvent. The crystallization of racemic axially chiral pyrimidinethione at high temperature led to the chiral breaking of symmetry up to 91% ee.

Viedma ripening: a reliable crystallisation method to reach single chirality

“…38,39 These complexes have achiral ligands but are chiral (denoted D or L instead of R and S) as a complex. 40 The combination of seeding and stirring gave the product with an ee of up to 91% through total spontaneous resolution. 11b).…”

Static and Dynamic Properties of 1,1′‐Bi‐2‐naphthol and Its Conjugated Acids and Bases

“…Indeed, rotational barriers are solvent-dependent, and differences enantiomerization barriers of 4.5 kJ mol À1 for 3-m-tolyl-4-tert-butylthiazoline-2-thione between isooctane and ethanol at 65.5 8C [32] and 12.5 kJ mol À1 for N-(1-naphthyl)-2(1H)-pyrimidinone between xylene and propan-1-ol at 90 8C have been reported in the literature. [33] Rotational barriers also vary with temperature depending on the value of the rotational activation entropy DS°. Experimental data and treatments of the first-order plots are reported in the Supporting Information.…”

Solid Phase Deracemization of an Atropisomer

“…In addition, this compound racemizes swiftly in apolar solvents at elevated temperatures ( t 1/2 = 4 min in xylene at 50 °C), whereas racemization at room temperature in polar solvents is negligible. 11 Racemization takes place relatively easily since it proceeds via a reversible ring-opening and closing-mechanism, 12 rather than via rotation around the chiral axis. Fujita and co-workers already showed that total spontaneous resolution can be achieved for this compound.…”