Use of temporary tethers in the intramolecular [2+2] photocycloaddition reactions of tetrahydrophthalimide derivatives: a new approach to complex tricyclic lactones
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- 作者：Ş ; irin Gü ; lten ; Andrew Sharpe ; James R. Baker ; Kevin I. Booker-Milburn
- 关键词：Photochemistry ; Cycloadditions ; Temporary tethers ; Acid-catalysed rearrangements
- 刊名：Tetrahedron
- 出版年：2007
- 出版时间：30 April 2007
- 年：2007
- 卷：63
- 期：18
- 页码：3659-3671
- 全文大小：471 K
文摘
The intramolecular [2+2] photocycloaddition reactions of a series of alkenols tethered to ethanolamine, l-(+)-valinol and R-(−)-2-phenylglycinol derived 3,4,5,6-tetrahydrophthalimides via a carbonate or silicon linkage have been examined. These [2+2] photocycloadditions gave the corresponding cyclobutanes in high yield with complete endo control in all cases and with diastereoselectivities as high as 8:1 with the chiral tethers. The cleavage of the temporary tethers by either desilylation or hydrolysis provided the endo diols. Cleavage of the ethanolamine linkage by reduction/hydrolysis precipitated an acid-catalysed fragmentation/ring expansion sequence to generate complex tricyclic lactones.