We claim a simple strategy for the synthesis of a collection of C(3')-spirodihydroisobenzo- furannulated and C(3')-spirodihydroisobenzo-furannulated nucleosides featuring a [2+2+2]- cyclotrimerization as the key reaction. The cyclotrimerization reactions are facile with the unprotected nucleosides having a diyne unit. When both alkynes of the diyne are terminal, the regioselectivity is poor. However, when one of the terminal alkynes is additionally substituted, the cyclotrimerizations are highly diastereoselective. Since the key bicycloannulation is the final step, this strategy provides flexibility in terms of the alkynes and is thus amenable for the synthesis of a focussed small molecule library.
我们提出了一种简单的合成策略,用于合成一系列C(3')-螺二氢
异苯并呋喃核苷和C(3')-螺二氢
异苯并呋喃核苷,其中的[2+2+2]环三聚反应是关键反应。未保护的核苷具有diyne基团,因此环三聚反应容易进行。当diyne的两个炔基都是末端炔基时,区域选择性较差。然而,当其中一个末端炔基另外还有取代基时,环三聚反应高度对映选择性。由于关键的双环化是最后一步,因此这种策略在炔基方面具有灵活性,因此适用于合成集中的小分子库。