N-heterocyclic carbene–palladium catalysts for the bisdiene cyclization-trapping reaction with sulfonamides under thermal and microwave conditions
摘要:
Simple palladium-N-heterocyclic carbene catalysts readily effect the palladium-catalyzed cyclization-trapping of bisdienes with sulfonamides. The reaction is quite efficient for a variety of sulfonamides and several bisdienes. For example, using 0.1% of the in situ generated or preformed (IMes)Pd(eta(3)-C3H5)Cl complex, the cyclization-trapping of a simple bisdiene with TsN(H)CH2Ph proceeds in good yield under thermal conditions (74-75%, 75 degrees C, 9 h). The same reaction run under microwave irradiation proceeds somewhat faster and in even higher yield (86%, 75 degrees C, 2.5 h). (c) 2005 Elsevier B.V. All rights reserved.
优化的钯-N-杂环卡宾催化剂体系可实现钯催化的双二烯环化-捕集,在0.01%的催化剂负载量下,苯酚的TON为7.6×10 3,TOF为280 h -1,其值比通常发现的高为此和相关的碳环化。反应很好地进行规模化,并且在没有进一步优化催化剂体系或反应条件的情况下以10毫摩尔规模以优异的产率获得了反式取代的六元环产物。