Download Chem 30B Midterm 1: Organic Chemistry Exam and more Exams Organic Chemistry in PDF only on Docsity! Last Name Student ID Number: Discussion Section – Day: Time: Circle the name of your TA: MIKE ROB Chem 30B Spring 2004 MIDTERM #1 (50 Min) Weds April 28th INTERPRETATION OF THE QUESTIONS IS PART OF THE EXAM – DO NOT ASK FOR THE QUESTIONS TO BE EXPLAINED TO YOU ONLY ANSWERS WRITTEN IN THE BOXES PROVIDED WILL BE GRADED ***DO NOT OPEN THIS EXAM UNTIL INSTRUCTED TO DO SO*** First Name MI Total Score / 100 Q1 Q2 Q3 Total Q4 Q5 Extra Credit / 25 / 14 / 20 / 17 / 24 / 15 / 100 "This is not the end. It is not the beginning of the end. But it is perhaps the end of the beginning" – Sir Winston Churchill 1 Question 1 For each of the reactions below, draw the final product and indicate clearly any relevant stereochemistry. For each reaction, indicate whether a single non-meso compound (S), a racemic mixture (R), or a meso compound (M), is formed, by writing the appropriate letter (S, R or M) in the smaller box to the right. (4 + 1 points each) CH2I2 Br / H2O (i) H2O / H+ Zn / Cu (ii) H2CrO4 (i) OsO4 / H2O2 (ii) HIO4 (i) mCPBA (ii) H2O / H+ 4 Question 4 In Chem 30B so far, you have seen how to make an epoxide from an alkene and a peroxy- acid such as mCPBA (route A), and also from an aldehyde and a sulfur ylid (route B). What are the reaction mechanisms for each of these routes – SHOW ALL STEPS. (7 points for A, 10 points for B) O RR R O Cl O O O H (mCPBA) S A B A B 5 Question 5 Shown below is a short synthetic scheme. In the large boxes (A, B, C , D , E), fill in the structures of plausible intermediate compounds – ONLY ONE STRUCTURE PER BOX. In the small box (F), fill in the reagent necessary to achieve the transformation of E (molecular formula C6H14O) into the final ketone product. Note: compounds C and E are formed as racemic mixtures. (4 points per box) HBr mCPBA (±) (ii) H+ / H2O A B Mg / Et2O C D (±) E F O (i) Ether Solvent C6H14O 6 Extra Credit Question The di-ene-yne compound shown below undergoes an alkyne-relayed ring-closing alkene metathesis reaction (when treated with the ruthenium catalyst) to give compound A which has a structure that contains 2 five-membered rings. What is the structure of A, and what is the mechanism of the reaction? Note: you may abbreviate the whole catalyst structure to [Ru] for the purposes of drawing the mechanism. (5 points for structure, 10 points for mechanism) O O Cy3P Ru PCy3 Cl Cl Ph A H H H H + CH2Cl2 (Solvent) Structure of A
