Ultrasound-promoted preparation of disteryl ethers catalyzed by montmorillonite K 10.
In the presence of montmorillonite K 10, 5(6)-unsaturated sterols (1) were heated under ultrasound at 45 degrees C in dichloromethane for 2-5.5 h to provide 3 beta,3'beta-5(6)/5'(6')-unsaturated disteryl ethers (2) in 35-79% yield. Meanwhile, 3 alpha,3'alpha-diandrost-5-en-17-one-3-yl ether (3a) and 3 alpha,3'alpha-dipregn-5-en-20-one-3-yl ether (3b) were also obtained as by-products from 3 beta-hydroxyl-androst-5-en-17-one (1a) and 3 beta-hydroxyl-pregnan-5-en-20-one (1b) respectively.
Department of Chemistry, Hebei University, Baoding 071002, People's Republic of China. orgsyn@nic.hbu.edu.cn
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