Intensive Organic Chemistry for Freshmen Due: Feb.23.2001 Problem Set 4 1. For each pair of compounds indicate which is the more oxidized at the carbon atom indicated by the arrow. a) OHO d) OH SH b) ON e) OCN c) OOHO f) NTsHNCN 2. Propose a reasonable mechanism for the following reaction. OHH2SO4, H2OOH2CrO4 3. What are the products of the following reactions) Explain. a) O1. LiAlH4, Et2O2. H2O b) OOSiMgBrEt2O c) Ohot conc.HBr d) ClOH-DMSO4. Explain the following observations. OHCl, H2OH3PO4, CH3OHOHClOHClOHOCH3OCH3OHminormajormajorminor 5. Explain the following observation. OOOBnBnOBnO1. LiAlH42. H2OOOBnBnOBnOOHOOBnBnOBnO OH+OOOBnBnOBnO1. AlH32. H2OOOBnBnOBnOOHmixture of bothmajor 6. Propose a biosynthetic pathway for α-pinene from geranyl pyrophosphate. Explain all crucial steps. OPPgeranyl pyrophosphatepinene 7. Provide a mechanism for the following cyclizations. a) OHHCO2HOHO b) OHSnCl4CH3NO2 (solvent)-23oC, 3 hrsHHredraw into 3D70 %c) The last step of the Takasago industrial synthesis of L-menthol; OZnBr2OHH2, NiOHL-menthol 8. Explain why the given product was formed. OHOHPhPhH2SO4OPhPh99 % yield 9. In problem 6, one of the geranylpyrophosphate double bonds must be isomerized from E to Z. Propose a reasonable mechanism for this enzyme-catalyzed reaction. Clearly indicate the role of the enzyme