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摘要
<jats:p>Starting from (<jats:italic>S</jats:italic>)-β-phenylalanine, easily accessible by lipase-catalyzed kinetic resolution, a chiral triamine was assembled by a reductive amination and finally cyclized to form the title compound <jats:bold>10</jats:bold>. In the crystals of the guanidinium benzoate salt the six membered rings of <jats:bold>10</jats:bold> adopt conformations close to an envelope with the phenyl substituents in pseudo-axial positions. The unprotonated guanidine <jats:bold>10</jats:bold> catalyzes Diels–Alder reactions of anthrones and maleimides (25–30% ee). It also promotes as a strong Brønsted base the retro-aldol reaction of some cycloadducts with kinetic resolution of the enantiomers. In three cases, the retro-aldol products (48–83% ee) could be recrystallized to high enantiopurity (≥95% ee). The absolute configuration of several compounds is supported by anomalous X-ray diffraction and by chemical correlation.</jats:p>
- 出版日期2016-8-19
