Increased Yields and Simplified Purification with a Second-Generation Cobalt Catalyst for the Oxidative Formation of <i>trans</i>-THF Rings
作者:Cory Palmer、Nicholas A. Morra、Andrew C. Stevens、Barbora Bajtos、Ben P. Machin、Brian L. Pagenkopf
DOI:10.1021/ol9023375
日期:2009.12.17
The synthesis of a second-generation cobalt catalyst for the formation of trans-THF products via the Mukaiyama aerobic oxidative cyclization is reported. Two procedures have been developed with the new water-soluble catalyst that give superior yields and greatly simplify purification compared to the previous catalysts.
NHC-Catalyzed Ring Expansion of Oxacycloalkane-2-carboxaldehydes: A Versatile Synthesis of Lactones
作者:Li Wang、Karen Thai、Michel Gravel
DOI:10.1021/ol8029005
日期:2009.2.19
Imidazolinium-derived carbenes catalyze the ring-expansion lactonization of oxacycloalkane-2-carboxaldehydes. A variety of functionalized five-, six-, and seven-memberedlactones can be formed efficiently under mild reaction conditions. The success of this new method for the construction of lactones is highly influenced by the electronic nature of the carbene catalyst.