Department of Chemistry, Seoul National University , Seoul 151-747, South Korea.
J Am Chem Soc. 2014 Jul 16;136(28):9918-21. doi: 10.1021/ja505721v. Epub 2014 Jul 1.
A pericyclic approach for the synthesis of six-membered ring structures is described. The method employs 1,3-dienes with a 1-sulfur substituent in a tandem sequence of Diels-Alder and retro-ene reactions. In this pairing of [4 + 2] cycloaddition and 1,5-sigmatropic rearrangement, 1-sulfenyl-1,3-dienes engage in Diels-Alder reactions with electron-deficient dienophiles. Subsequently, the sulfenyl group of the cycloadducts is oxidized and unmasked to form allylic sulfinic acids, which undergo sterospecific reductive transposition via sulfur dioxide extrusion. The sequence can also include an inverse electron demand Diels-Alder reaction by using a 1-sulfonyl-1,3-diene. This combination of two pericyclic events offers novel stereocontrolled access to cyclohexenes that are inaccessible via a direct [4 + 2] cycloaddition route.
描述了一种用于合成六元环结构的周环反应方法。该方法采用带有 1-硫取代基的 1,3-二烯，通过 Diels-Alder 和逆烯反应的串联序列进行反应。在[4+2]环加成和 1,5-σ迁移重排的这种配对中，1-亚磺酰基-1,3-二烯与缺电子的亲二烯体发生 Diels-Alder 反应。随后，环加成物中的亚磺酰基被氧化并暴露出来，形成烯丙基磺酸，它们通过二氧化硫的排出进行立体特异性的还原重排。该序列还可以通过使用 1-磺酰基-1,3-二烯进行逆电子需求 Diels-Alder 反应。这两个周环反应的组合提供了一种新颖的立体控制方法，可获得通过直接[4+2]环加成途径无法获得的环己烯。
