ame Page 1 I. (8 points) omplete the following reactions as directed. Transformations requiring sequential experimental steps should be numbered appropriately. Show the major organic product(s) unless otherwise specified. Abbreviations for reagents are not allowed. If a product forms as a stereoisomeric mixture, draw one and write "+enantiomer" or "+diastereomer" in the box. A. l 2 All Pt + enantiomer. l 2 All 2. 1) 2) 2 2 D. + enantiomer 8
ame Page 2 II. (7 points) A. omplete the following multi-step reactions starting from the starting material in the center below. e sure to number steps where required. If a mixture of stereoisomers results, draw one and write "+enantiomer" or "+diastereomer" in the box. If a mixture of structural isomers results, draw the predicted major product. only this stereoisomer 1. Sl 2. a. a 1. Sl 2. a only this stereoisomer S 2 1. Sl 1. a 2. as 2 2. I. The following reaction was recently reported (Tetrahedron, 200, 2, 717). In the box below, show the mechanism of this reaction. Use - and - for any onsted acids or bases, if needed. TE: Under certain conditions, alkoxy groups (like " ") can react with a Lewis acid to form a good leaving group. F 2 l 2 2 o,h F F : - 17
A. III. ( points) ame Page When ompound A is treated with a stong hindered base, a mixture of structurally isomeric products results. Draw these products. i) K 2 + ompound A ii) What mechanism is predictedtoform these products? Product Product (circle one) S 1 S 2 E1 E2 Electophilic addition EAS More stable: Why? iii) Due to relative stability, (circle one) one of the two products above forms to a much Product Elimination to form product produces greater extent then the other. an aromatic ring. Which is the more stable Product product and why? 2. Each of the following reactions afford one predominant monosubstitution product. Draw the product. i) S 2 S S ii ) 2 ai I 2 iii ) 2 2 2 S Fe S iv ) l l 2
ame IV. (9 points) Page The following three-step reaction can create two different regioisomeric products. omplete the reaction mechanism with curved arrows and structures as needed and as indicated. Use - and - for any onsted acids or bases needed. Two regioisomeric products 2 S (cat) ii) intermediate leading to the major product & curved arrows f or step 2 Intermediate 1A iv) structure and arrows Intermediate 2A i) curved arrow mechanism f or step 1 iii) intermediate leading to the minor product & curved arrows f or step 2 Intermediate 1 v) structure and arrows : - Include the intermediate :- structure and the curved arrows for the next step in these boxes! Intermediate 2 Product A vi) M ajor regioisomeric product viii) Draw the structure of the transition state from the step between the starting material and Intermediate 1A. vi) transition state drawing Product vii) M inor regioisomeric product ix) Draw an energy diagram of the above reaction. Indicate the locations of all intermediates (I1A, I1, I2A, I2), and all transition states (). Use the locations of the starting materials (SM) and products (A and ) already drawn. - E I1 I1A I2 + SM I2A A reaction progress
A. ame V. ( points) Page There are seven molecules shown. For each question, you should circle the letter corresponding to the molecule for which the statement is true. You will be graded by the molecule, not the question, A E D F G i. ircle the letters for those molecules (A-G) that... a)... has an enantiomer b)... has at least one (R)-stereocenter c)... is optically active d)... is unique and has no stereoisomers e)... has at least one optically inactive diastereomer f)... has at least one optically active diastereomer g)... is a meso compound h)... forms a racemic mixture upon addition by s S SR E Z E A D E F G A D E F G A D E F G A D E F G A D E F G A D E F G A D E F G A D E F G ii. Give the full name of compounds and F in the appropriate box below. ompound. For each of the following compounds, count the number of electrons contained in the cyclic -isitaromatic? i) electrons aromatic? ii) electrons aromatic? iii) electrons o o iv) ompound F (S)-2-bromo-2-methylpentan--ol (Z)-but-2-ene electrons aromatic? v) electrons o 12 aromatic? o system aromatic? o
ame VI. (0 points) Page A. i. The following bromination reaction results in the formation of two stereoisomeric products. Draw them in the spaces below. 2 ompound D ompound E ii. Draw in the substituents for the most stable chair form of compounds D and E on the chairs below. You may use the abbreviation for the isopropyl groups. e sure to put the right compound in each box. The information in the table on the right may be useful. ompound D ompound E equitorial axial G o eq -X G o eq(kcal/mol) - 1.7-2 1.8 -( ) 2 2.1 -( ). - 1.0 -l 0. - 0. iii. When the mixture of compounds D and E was reacted with sodium ethoxide in ethanol for a short period of time, only one of the two compounds reacted. Which compound reacted, why, and what is the product of that reaction? ompound D or ompound E a 2 2 Product F Which reacts with ethoxide? (circle one) ompound D Why that one and not the other? ne or two sentences will suffice. ompound E In compound E, one of the bromines is ATI to a That is not true in compound D. -. Draw Product F here