D-Proline

The products can simply be transformed into multiple substituted D-proline derivatives .

所得产物经简单转化可以制备多取代D-脯氨酸衍生物。

However , D-histidine and . D-proline are difficult to obtained from natural products in large quantities and , therefore , are very expensive .

而D-组氨酸和D-脯氨酸却难以从自然产品中大量提取，因此其价格十分昂贵。