The angle strain induced by ring annulation on a spiro-type naphthofuran weakens its C(sp3)–O bond at the opposite peri-position and endows expandability, so that quite different bond lengths [1.493(3)–1.526(6) Å] are determined for the elongated C(sp3)–O bond of the corresponding spiro-acenaphthofuran derivative upon X-ray analyses of its pseudopolymorphs.
螺型
萘呋喃的环化引起的角应变削弱了其在相反周位置上的 C(sp3)-O 键,并赋予其可扩展性,因此在对其假多晶型进行 X 射线分析时,确定了相应螺型
苊呋喃衍
生物的拉长 C(sp3)-O 键的键长[1.493(3)-1.526(6)埃]存在很大差异。