Synthesis of Caged\nHMG-CoA Reductase Substrates for\nthe Elucidation of Cellular Pathways

The synthesis of photocaged substrates of the biologically\nimportant\nenzyme HMG-CoA reductase is reported. HMG-CoA bearing a <i>p</i>-hydroxyphenacyl (pHP) photocage moiety was synthesized in an overall\nyield of 14% over seven steps in addition to caged forms of mevalonate\nand mevaldehyde. The absorption maximum and quantum yield for the\ndecaging of the photocaged compounds are dependent on pH with a λ<sub>max</sub> of 330 nm and a ϕ of 5%, respectively, at pH 9.1\nbut a λ<sub>max</sub> of 290 nm and a ϕ of 16%, respectively,\nat pH 6.7.