During the lignification of grass cell walls, ferulate acts like a nucleation site that can cross couple with monolignols, i.e. coniferyl alcohol and sinapyl alcohol, to form dimeric products. Here we investigated in detail the ferulate-sinapyl alcohol cross-coupling products in an effort on better understanding the nature and scope of lignin-ferulate interactions. In a biomimetic oxidative system, sinapyl alcohol (SA) reacted with ethyl ferulate (FA), a simplified model for feruloyl polysaccharides in plants, to give a mixture of dozens of dimeric products. We delineated the structure of each product by GC-MS and NMR characterizations. It was found that sinapyl alcohol readily reacts with ethyl ferulate producing various cross-coupled dimers including SA-(β–5)-FA (compound 6), SA-(β–8)-FA (both ester and lactones, compounds 7 and 9), and SA-(β–O–4)-FA (compound 8) cross-coupled products in addition to homo-coupled products from ethyl ferulate or sinapyl alcohol. SA-(β–O–4)-FA 8 was identified for the first time in a vitro free radical biomimetic system and the homo-coupled SA-(β–O–4)-SA 3 from sinapyl alcohol was accurately quantified as less than 5%, while the half-open syringaresinol 5 was discovered when dimerization of SA was catalyzed by peroxidase in a biomimetic buffer system. Moreover, one new compound 18 formed by the cross-coupled linkage SA-(β–5)-FA (de-protonated) was identified by GC-MS and NMR, and one possible FA-(8–β)-SA dimer 19* was proposed.

在草细胞壁的木质化过程中，阿魏酸盐的作用类似于成核位点，可以与单木酚醇（即松柏醇和芥子醇）交叉偶联，形成二聚体产物。在这里，我们详细研究了阿魏酸-芥子醇的交叉偶联产物，以更好地了解木质素-阿魏酸酯相互作用的性质和范围。在仿生氧化系统中，芥子醇（SA）与阿魏酸乙酯（FA）（植物中阿魏酰多糖的简化模型）反应，得到数十种二聚体产物的混合物。我们通过GC-MS和NMR表征描绘了每种产品的结构。发现芥子醇容易与阿魏酸乙酯反应，生成各种交叉偶联的二聚体，包括SA-（β-5）-FA（化合物6），SA-（β-8）-FA（酯和内酯，化合物7和9）和SA-（β-O-4）-FA（化合物8）交叉偶联产物，除均相偶联产物外来自阿魏酸乙酯或芥子醇。SA-（β-O-4）-FA 8被确定为第一次在一个体外自由基仿生系统和均聚耦合SA-（β-O-4）-SA 3从芥子醇被准确地量化为少低于5％，而当在仿生缓冲系统中通过过氧化物酶催化SA的二聚化时，发现半开放的丁香脂醇5。此外，一种新化合物18通过GC-MS和NMR鉴定了由交叉偶联的SA-（β-5）-FA（去质子化）形成的分子，并提出了一种可能的FA-（8-β）-SA二聚体19 *。