Novelroute for the construction of chromans from benzylic and aliphatic alcohols in the presence of NaHSO4/SiO2 has been developed. In this reaction, substituted olefins are formed from benzylic and aliphatic alcohols and then converted to chromans through intramolecular cyclization. Twenty novel chromans were synthesized by this simple procedure.
Brønsted acid catalyzed [4 + 2] cycloaddition for the synthesis of bisbenzannulated spiroketals with antifungal activities
作者:Teng Hu、Yuxuan Zhao、Xiaoyan Luo、Zhong Li、Wu-Lin Yang
DOI:10.1039/d4ob00584h
日期:——
The intermolecular [4 + 2] cycloaddition of o-hydroxy benzyl alcohols with isochroman ketals was realized by CF3CO2H catalysis. A broad range of bisbenzannulated [6,6]-spiroketals were formed under the metal-free mild conditions in moderate to excellent yields (45–98%) with mostly excellent diastereoselectivities (up to >20 : 1 dr). Furthermore, the enantioselective version was also preliminarily investigated
通过CF 3 CO 2 H催化实现邻羟基苯甲醇与异色满缩酮的分子间[4+2]环加成反应。在无金属的温和条件下,形成了多种双苯环化[6,6]-螺缩酮,产率中等至优异(45-98%),并且具有优异的非对映选择性(高达>20:1 dr)。此外,还初步研究了对映选择性形式,在Sc(OTf) 3 /Feng的手性N , N '-二氧化物配体存在下,得到了双苯环化[6,6]-螺酮缩醛,其ee含量为61%。一些双苯环化[6,6]-螺缩酮产品对核盘菌和立枯丝核菌表现出良好的体外抗真菌活性。