Chem 634Professor FoxExam 1March 9, 20041 hour 15 minYour Name__KEY_________________a1. Show the products of the following transformations. Mechanistic detailsare not required, but be sure to indicate relative stereochemistrywhere necessary (four parts; 5 points each)bChem 634 Exam 1 Your Name___________________March 9, 2004O OCH31) BuLi, TMEDA2) TMSClO OCH3TMSONHPhOCH3H3C2 equiv Bu2CuLiCH3H3C Bu(CO)4FeNa21) EtI, Ph3P2) PhCH2Brc1. (continued)dChem 634 Exam 1 Your Name___________________March 9, 2004CH3OPhPh2(But)SiOEtOMeMeMgBrPh2(But)SiOMeMeHOEta2. The reactions below would not proceed as indicated. Provide a brief but detailed explanation, and indicate the structure of the product(s) that would be formed instead of (or in addition to) the product that is drawn (5 points each). bChem 634 Exam 1 Your Name___________________March 9, 2004OOOmCPBAXOOmore substitutedcarbon migratesPh MeEt I Et2CuLi•LiCNTHFPh MeEt EtUnlike bromides and tosylates, the reactions of cuprates with alkyliodides typically occurs with stereochemical scrambling. The mechanism is beleived to proceed via electron transfer. Thus, the other diastereomer (shown below) is also formed.Ph MeEt Etc2. (continued). dChem 634 Exam 1 Your Name___________________March 9, 2004CO2MeBrCO2MeCH3CH31) LDA2)PhCO2HPh OHMeMe1) MeLi2) H+XPh O–OdeprotonateMeLi Ph O–O–Me2Li+MeLithe dianion is stableand does not decomposeuntil the aqueous workupH+wkupPh MeOX–OMeOHHBrH3CCO2MeCH3Equatorial delivery of the nucleophile. Alkylation of exocyclic enolates is dominated by sterics-- 1,3 Diaxial interactions prevent delivery from the top faceChem 634 Exam 1 Your Name___________________March 9, 20043. This question has two parts, both of which deal with the reaction below:3a. Provide an arrow pushing mechanism for the reaction above. For this part of theproblem, it is not necessary to explain the stereochemical aspects of the reaction. Justpush the arrows and show how the final product is formed. (20 points)OCO2EtEtMeMgBrMeEtOOOOEtMeOCO2EtEtMeMgBrMeEtOOOOEtMeEtMe–OEtO2CMeMgBranionicoxy-CopeEtMe–OOOEtEtOOEtMe–OChem 634 Exam 1 Your Name___________________March 9, 20043b. Provide a detailed model with explains all of the stereochemical aspects(stereocenters and alkene stereochemistry). (20 points)OCO2Et CO2EtR MgBrOHRnote the stereochemistry of the following transformation when detailing your mechanism. You mayconsider this to be general for the reactions of Grignard reagents with β -ketoestersthen H+OCO2EtEtMeMgBrMeEtOOOOEtMeEtMe–OEtO2CEtO2CO–EtMeO–EtMeOEtOOEtMeO–EtOMeEtOOChem 634 Exam 1 Your Name___________________March 9, 2004PhMePhMeHO2C MeMeOH4. Outline a multistep synthesis (20 points)PhMeHO2C MeMePhMeMeOORMePhMeMeOHClaisenSelectiveenolizationPhMeOFelkin-controlledadditionoxidPhMeOHRetrosynthesisexample of an acceptable Forward synthesisPhMeOHDMSO(COCl)2Et3NPhMeOPhMeMeOHBrMgMeEtCOClpyridinePhMeMeOOMePhMeMeOOTBSMeLDATHF/HMPAthenTBSClwarm to rtthen H3O+PhMeHO2C
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