Dramatic Base-Oriented Chemoselective Tandem Wacker Cyclizations: Synthesis of Bisbenzannelated Spiroketals and 2-Substituted Chromans
作者:Jijun Xue、Ying Li、Zhijun Xin、Yuan Zhang、Hua Tao
DOI:10.1055/s-0030-1260775
日期:2011.7
A Pd(II)/Cu(II)-catalyzed chemoselective tandem aerobic cyclization of phenolic olefins leads to [5,6]-bisbenzannelated spiroketals or 2-substituted chromans, wherein it was interestingly found that the presence or absence of base could be responsible for the tunable selectivity. The [5,6]-bisbenzannelated spiroketals were achieved from tandem Wacker cyclization-aroxylation in moderate yields in the absence of base, and 2-substituted chromans were formed through base-mediated Pd(II)/Cu(II)-catalyzed tandem Wacker cyclization-Michael addition in good yields.