Influence of the Aromatic Substituent on the Reactivity of (R)-N-Methyl-1-phenyl-2-(1-piperidinyl)ethanamine Cuprates in Enantioselective Conjugate Addition
Influence of the Aromatic Substituent on the Reactivity of (R)-N-Methyl-1-phenyl-2-(1-piperidinyl)ethanamine Cuprates in Enantioselective Conjugate Addition
coupling method, to assign the absoluteconfiguration of the benzylic stereogenic center of 1-aryl-1,2-diols. According to this method, it is only necessary to prepare the 4-biphenylboronic esters of the diols and to record their CDspectra in the 230−300 nm range, i.e., in the range corresponding to the long-axis 1La transition of the biphenyl chromophore. From the sign of the CD couplet or Cotton effect
我们在此基于激子偶联方法描述一种简单,通用且可靠的非经验方法,以分配1-芳基-1,2-二醇的苄基立体异构中心的绝对构型。根据该方法,仅需制备二醇的4-联苯硼酸酯并记录其在230-300 nm范围内(即在对应于长轴1 L a的范围内)的CD光谱联苯发色团的过渡。从260 nm处的CD偶联或棉花效应的征兆,可以知道由芳基和联苯发色团跃迁定义的手性,然后确定苄基碳的绝对构型。通过这种方法,已经制定了简单的规则,使我们能够建立许多种类的1-芳基-1,2-二醇的绝对构型。
Determination of the Absolute Configuration of 1-Arylethane-1,2-diols by a Nonempirical Analysis of the CD Spectra of Their 4-Biphenylboronates
[GRAPHICS]1-Arylethane-1,2-diols 1, reacting with 4-biphenylboronic acid 2, form the conformationally defined boronates 3 where the aryl and biphenyl chromophores assume a fixed and known relative disposition. These chromophores thus define an exciton coupled system, whose chirality (revealed by the sign of the biphenyl On band at 260 nm) allows an unambiguous assignment of the absolute configuration of the stereogenic center. This approach provides the hitherto unreported absolute configuration of diols 1c-f.
Influence of the Aromatic Substituent on the Reactivity of (R)-N-Methyl-1-phenyl-2-(1-piperidinyl)ethanamine Cuprates in Enantioselective Conjugate Addition