Answer Key for Problem Set 4 1. a) OHO ⇑⇑⇑⇑ d) OH SH ≡≡≡≡ b) ON ⇑⇑⇑⇑ e) OCN ⇑⇑⇑⇑ c) OOHO ⇑⇑⇑⇑ f) NTsHNCN ⇑⇑⇑⇑ 2. OHH2SO4, H2OOH2CrO4OHH2O 3. a) O1. LiAlH4, Et2O2. H2OOHSN2 like b) OOSiMgBrEt2OOSiOHPh c) Ohot conc.HBrBrOHBrBrHBrd) ClOH-DMSO no reaction (substitution very slow) 4. OHCl, H2OH3PO4, CH3OHOHClOHClOHOCH3OCH3OHminormajormajorminorCl- decent Nu, attacks less hindered siteH2PO4- and CH3OH are weak Nu, there is 'time' to open the ringOHHCl and H3PO4 acid strength are about equal, HOWEVER, Cl- is better Nu than H2PO4- 5.OOOBnBnOBnO1. LiAlH42. H2OOOBnBnOBnOOHOOBnBnOBnO OH+OOOBnBnOBnO1. AlH32. H2OOOBnBnOBnOOHmixture of bothmajorOOOBnBnOBnOAlH3AlH3 strong Lewis acid SN2 likeHOOOBnBnOBnOAlH3OOBnBnOBnOOH 6. OPPgeranyl pyrophosphateE-Z isom.OPPH 7. a) OHHCO2HOHOHCOO-b) OHSnCl4CH3NO2 (solvent)-23oC, 3 hrsHH70 %SnCl4strong Lewis acidHH c) The last step of the Takasago industrial synthesis of L-menthol; OZnBr2OHH2, NiOHL-mentholOZnBr2(Lewis acid)OZnBr2H 8. OHOHPhPhH2SO4OPhPhPhPhOHmuch more stableOHPhPhOHPhPh9. OPPEOPPZEnz-X-Hdouble bond protonationOPProtationpromoted by enzyme(cavity