Easy access to medium rings by entropy/strain reduction. Part 2. The ready availability of cis,cis-2,4-diene-1,6-diols and derived dibromides allows a simple and mild route to substituted 2,7-dihydro-1H-azepines
作者:James G. Walsh、Patrick J. Furlong、Declan G. Gilheany
DOI:10.1039/a905387e
日期:——
Hydride reduction of a series of substituted cis,cis-2,4-diene-1,6-dioates 1 provided the corresponding 1,6-diols 2, most of which were converted to the 1,6-dibromides 3 with phosphorus tribromide. Reaction of a selection of these dibromides with primary alkylamines in the presence of sodium hydrogen carbonate provided a simple and mild synthesis of substituted dihydroazepines 4. The cleanest products were obtained with toluene-p-sulfonamide as the nitrogen source. Bis(dihydroazepines) 5 were also synthesised from diamines while hydrazine yielded a hydrazinium salt 6. Aniline could be induced to take part in the reaction in the presence of butyllithium furnishing a low yield of N-phenyldihydroazepines 8.
一系列取代的顺,顺-2,4-二烯-1,6-二羧酸酯1通过氢化物还原得到相应的1,6-二醇2,其中大部分在磷三溴存在下转化为1,6-二溴化物3。在碳酸氢钠存在下,这些二溴化物与伯烷基胺反应,提供了简单温和的取代二氢氮杂卓4的合成途径。使用对甲苯磺酰胺作为氮源时,产物最为纯净。双(二氢氮杂卓)5也从二胺合成,而肼生成肼盐6。在丁基锂存在下,苯胺可以参与反应,以低产率得到N-苯基二氢氮杂卓8。