The present study describes a rapid, simple and straightforward approach to the synthesis of 1,8-dioxo-octahydroxanthenes, 14-phenyl-14H-dibenzo[a,j]xanthene and tetrahydrobenzoxanthene-11-ones under solvent-free conditions using sulfated polyborate as a highly efficient catalyst. The procedure offers several advantages including cleaner reaction profile, mild reaction condition, economic, recyclable and environmentally benign catalyst, high yields, simple experimental and workup procedures. While non-extractive work up/purification, along with reusability of catalyst make this method economically affordable for large scale.

中文翻译：

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可回收的硫酸化多硼酸盐催化快速，高效且无溶剂地合成（不）对称的黄嘌呤

本研究描述了一种在无溶剂条件下使用硫酸盐快速合成1,8-二氧-八氢氧杂蒽，14-苯基-14 H-二苯并[ a，j ]氧杂蒽和四氢苯并氧杂蒽-11的快速，简单和直接的方法。多硼酸盐作为高效催化剂。该方法具有几个优点，包括更清洁的反应曲线，温和的反应条件，经济，可循环使用和对环境无害的催化剂，高收率，简单的实验和后处理程序。尽管非萃取性后处理/纯化以及催化剂的可重复使用性使该方法在经济上可大规模使用。