3-聯烯基-4-亞甲基四氫呋喃的合成與其衍生化

Abstract

聯烯由於結構的特殊性，具獨特的化學性質，常被用於有機合成上，在天然物、藥物與一些功能性材料上也有廣泛的應用性。本研究成功使用 (2-丙炔氧基)烯炔醚1在鈀金屬的催化下合成3-聯烯基-4-亞甲基四氫呋喃2；進而針對2的反應性做進一步探討。若使用碘分子與三取代聯烯2 (R3 = Ph) 進行反應，其會進行分子內一連串親電性加成與取代反應，生成三環分子6。而若將雙取代聯烯2 (R3 = H) 置於溝呂木－赫克反應條件下，則可以通過連續的遷移插入反應得到四氫異苯並呋喃4；此結構可進一步在2,3-二氯-5,6-二氰對苯醌 (DDQ) 的幫助下進行脫氫反應，得到二氫異苯並呋喃5。本研究拓展了零價鈀金屬對炔基的活化，提供一種嶄新的方法合成多取代聯烯2，也揭示了利用2產生三環化合物 6 和四氫異苯並呋喃 4 的新合成方法。

Due to the unique structural characteristics, allenes exhibit distinct chemical properties, allowing them to be invaluable in organic synthesis typically for natural products, pharmaceuticals, and functional materials. In this research, we have developed a new methodology to construct 3-allenyl-4-methylenetetrahydrofurans 2 from Pd-catalyzed cyclization of (Z)-5-(prop-2-yn-1-yloxy)pent-3-en-1-yne 1 through the vinyl-Pd intermediate I. Reactivity of 2 was further investigated. Treatment of the trisubstituted allene (2, R3 = Ph) with iodine caused a cascade cyclization to yield a spiral 5-5-5-tricyclic ring 6. On the other hand, reaction of the disubstituted allene (2, R3 = H) with aryl iodide proceeded a cascade insertion to produce tetrahydroisobenzofurans 4 under Heck reaction conditions. The oxidation of 4 with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) resulted in the formation of 1,3-dihydroisobenzofuran 5. This research extends a palladium catalyzed activation of alkynyl groups for the synthesis of multi-substituted allenyltetrahydrofurans 2 and reveals new reactivity of 2 leading to 5-5-5-tricyclic rings 6 and tetrahydroisobenzofurans 4.