Synthesis of Heteroarenes via Radical Cyclisation onto Nitriles
作者:W. Russell Bowman、Colin F. Bridge、Martin O. Cloonan、David C. Leach
DOI:10.1055/s-2001-14592
日期:——
A new protocol for the synthesis of tetracyclic nitrogen heteroarenes using cascade radical cyclisation has been developed. The key steps involve 5-exo vinyl radical cyclisation onto nitriles to yield intermediate iminyl radicals which cyclise onto an arene rings. Rings A-D of the anticancer alkaloids camptothecin, mappicine and nothapodytines A and B have been synthesised using this protocol.
Synthesis of the Parent and Substituted Tetracyclic ABCD Ring Cores of Camptothecins via 1-(3-Aryl-2-propynyl)- 1,6-dihydro-6-oxo-2-pyridinecarbonitriles
作者:Weixiang Dai、Jeffrey L. Petersen、Kung K. Wang
DOI:10.1021/ol0620242
日期:2006.9.1
pathway to the parent and substituted ABCD ring cores of the camptothecin family of alkaloids was developed. The N-alkylation of 1,6-dihydro-6-oxo-2-pyridinecarbonitrile (2) with 3-bromo-1-phenylpropyne provided 3a using Curran's protocol. Treatment of 3a with a catalytic amount of DBU (5 mol %) at 110 degrees C for 12 h produced indolizino[1,2-b]quinolin-9(11H)-one (6a), the parent ABCD ring core of camptothecin