Synthesis and chemistry of N-arylated pyrano[2,3-c]pyrazoles
作者:J. Geno Samaritoni、Scott Thornburgh、Paul R. Graupner、David H. Cooper
DOI:10.1002/jhet.5570440623
日期:2007.11
activated aryl halides. Sterically demanding groups such as phenyl as in 5 reduce reactivity significantly while electronwithdrawing substituents such as trifluoromethyl and phenyl at C4 of the pyranone ring as in 10 and 15 render the pyranone carbonyl particularly susceptible to attack by nucleophiles resulting in ring-opening to give novel crotonyl derivatives. Proof of structure required a variety
可以通过在DMF中用六甲基二硅叠氮化锂生成1(R H)的阴离子并用活化的芳基卤化物淬灭来选择性地制备新型N 2-芳基吡喃并[2,3 - c ]吡唑-6-酮2。立体要求较高的基团(如5中的苯基)显着降低了反应活性,而吡喃酮环的C4处的吸电子取代基(如三氟甲基和苯基)则如10和15中所示使吡喃酮羰基特别容易受到亲核试剂的攻击而导致开环,从而产生新的巴豆酰基衍生物。结构验证需要涉及质子,碳和氮原子核的多种核磁共振方法。