Studies on A Novel Asymmetric Cycloaddition Using Optically Active <alpha> , <beta> -Unsaturated Sulfoxides

研究了取代芳基亚硫醚(乙烯基亚砜)的不对称Diels-Alder反应。从S-顺式或S-反式构象中硫孤对一侧的二烯方法的有利方向解释了这种高的非对映选择性，并根据S-O与取代基α&gt或β&gt之间的偶极-偶极和/或空间相互作用合理地解释了乙烯基亚砜的构象择优；另一方面，用2-吡啶亚磺基取代对甲苯亚磺基大大提高了反应活性，并通过与呋喃的环加成反应保持了高的非对映选择性，得到了7-恶二环[2.2.1]HEPT-5-烯-2-羧酸衍生物。实现了不对称Diels-Alder反应在某些生物活性天然产物的手性合成中的应用。

Asymmetric Diels-Alder reaction using substituted arylsulfinylethenes (vinyl sulfoxides) has been studied. The high diastereoselectivity was interpreted in terms of the favored direction of the diene approach from the side of the sulfur lone pair in energetically favored s-cis or s-trans conformers and the conformational preferences in vinyl sulfoxides are rationalized on the basis of dipole-dipole and/or steric interactions between S-O and the substituents at <alpha> or <beta> position.On the otherhand, the use of 2-pyridylsulfinyl group in place of p-tolyl-sulfinyl group enhanced the reactivity considerably and the high diastereoselectivity was also maintained by the cycloaddition with furan to give 7-oxabicyclo [2.2.1]hept-5-ene-2-carboxylic acid derivatives. The application of the asymmetric Diels-Alder reaction to the chiral synthesis of some biologically active natural products was achieved.