Addition of cyclopentadiene and 2-trimethylsilyloxyfuran to quinones bearing a menthyl ester chiral auxiliary
作者:Margaret A Brimble、Letecia J Duncalf、David C.W Reid、Tabitha R Roberts
DOI:10.1016/s0040-4020(98)00211-7
日期:1998.5
Addition of cyclopentadiene to 2-carbomethoxy-1,4-benzoquinone 9 afforded Diels-Alder adduct 10 using the Lewis acids ZnCl2 and ZnBr2 whereas the fragmenatation product 11 was the major product when using SnCl4 and TiCl4. Addition of cyclopentadiene to 1,4-benzoquinone 8 bearing a menthyl ester at C-2 afforded Diels-alder adduct 12 in moderate diastereomeric excess using ZnCl2 and ZnBr2 as Lewis acids