Tosylhydrazine mediated conjugate reduction and sequential reductive coupling cyclization: synthesis of 2-arylchromans
摘要:
Tosylhydrazine mediated conjugate reduction of 2-hydroxyl chalcones and sequential reductive coupling cyclization is described. This is an unprecedented protocol and an extremely efficient method for a one-pot domino synthesis of 2-arylchromans in good to excellent yields from commercially available, cheap starting materials. More importantly, the two-step reactions can be easily controlled to afford dihydrochalcones or 2-arylchromans by the mole amounts of tosylhydrazine. Furthermore, the operational simplicity of the process and the high functional group tolerance are remarkable. (C) 2015 Elsevier Ltd. All rights reserved.
An unexpected rearrangement-hydration reaction sequence of 2H-chromenes to dihydrochalcones under catalysis of HAuCl4
摘要:
2-Aryl-2H-chromenes in aqueous DCM medium under catalysis of HAuCl4 are converted into 3-(2-hydroxyaryl)-1-arylpropan-1-ones through hydration-rearrangement reaction sequence in very good yield. The key step probably involves the [1,5] hydride shift followed by the hydrolysis under the reaction condition. The notable advantages of this method are operational simplicity and ease of isolation of products and also provide a pathway to convert the chalcone into DHCs with the transposition of carbonyl group. (C) 2012 Elsevier Ltd. All rights reserved.