%A P Wipf %A CR Hopkins %J Journal of Organic Chemistry %T Efficient synthesis of 1,4-dihydro-2H-isoquinoline-3,5,8-triones via cyclobutene ring expansion %N 18 %P 6881 - 6887 %V 64 %D 1999 %R 10.1021/jo990089v %L pittir20629