Page 1 I 38 points A a When molecule 1 is heated in the presence of lithium bromide an unusual transformation occurs through a sequence of two reactions Provide curved arrow s to illustrate the conversion of molecule 1 to intermediate 2 Then provide the structure of the product 3 formed in the second reaction use the curved arrows as guide Name H H Br Li PhO PhO Br H H PhO 1 H H N iPr OTs 3 Li Br heat N iPr 2 N iPr connectivity 3 stereo 3 draw product 3 OTs no partial draw arrow s b The conversion of intermediate 2 to product 3 is an example of what type of reaction circle the single best description SN1 reaction reduction reaction electrophilic addition reaction Bronsted acid base reaction complexation decomplexation reaction SN2 reaction E1 reaction E2 reaction 6 Li OTs 3 B For each of the following molecules provide the number of electrons in the ring and indicate whether or not the molecule is aromatic a Aromatic b Aromatic H3C H3C CH3 O N N O of electrons 6 Yes No no partial 5 of electrons 4 S Yes No no partial O H3C O 5 note to graders answer 2 is ok C For the molecule shown below assign the stereochemical configuration of the selected tetrahedral carbon stereocenters R or S and the alkene E or Z that are indicated by the arrows note that you do not have to assign the configuration of every stereocenter in the molecule If R S or E Z labels are not applicable because a carbon indicated by an arrow is not a stereocenter or the alkene cannot be assigned as E or Z then circle neither E Z neither H H O HO H3C R S neither CH3 H O OH H O H H O H H R S neither O H R S neither 4 for each incorrect answer 16 Page 2 II 43 points A Provide the reagents or structures as necessary to complete the following sequences of reactions If more than one synthetic step is required number them sequentially You may use abbreviations for reagents e g TsCl but not acronyms e g mCPBA draw the structure instead a Name OH H3C H3C Br H Br Br b CH3 H3C Br Br OH H Na or other base w conjugate acid pKa 17 no partial one step only 5 O no partial R OOH any R group ok e g CH3 but must be a real group not R 5 one step only H H3C O H O OH H 1 TsCl 2 equivalents pyridine 2 equivalents 2 N 2 equivalents N H3C H3C O H H3C H3C O H Br Br Br Br enantiomer no partial O H O H3C product with no stereocenters 6 no partial OH AlCl3 Cl K O or any other strong base with conjugate acid pKa 13 no partial 5 H NMR 6 peaks 4 4 1 2 2 1 CNMR 7 peaks 6 major product connectivity 3 then stereo 3 1 BH3 2 H2O2 NaOH minor product OH diastereomer B Using lines dashes and wedges to indicate stereochemistry if when appropriate draw the structure of 2R 4S 4 cyclopropyl 4 iodobutan 2 ol 6 HO H H I 2 points per error 10 c d e Name Page 3 III 36 points A For each of the pairs of molecules drawn below place letters in the corner boxes corresponding to all accurate descriptions of the relationship between the two molecules a Cl Cl OH HO OH order of letters is not important S all letters that apply C H OR D H no partial 6 all letters that apply B F G H no partial 6 A enantiomers B diastereomers C different conformations of the same molecule D identical conformations of the same molecule E constitutional isomers F stereoisomers G different molecules H both are optically active I neither is optically active HO S b c Cl Cl CH3 Cl CH3 CH3 order of letters is not important H H3C H all letters that apply Cl G I no partial CH3 order of letters is not important Cl 6 B Chlorogenic acid is a naturally ocurring molecule found in coffee beans The pKa of Chlorogenic acid is 3 4 and the pKa of its conjugate base is 9 a Provide the structure of the major species present in a pH 8 5 solution of chlorogenic acid OH OH O HO OH HO O O OH OH OH O HO O HO O O OH Chlorogenic Acid pKa 3 4 pKa of Conjugate Base 9 chlorogenic acid at pH 8 5 b Which of the following bases can completely deprotonate Keq 103 the most acidic proton in chlorogenic acid circle all that can no partial 6 O K O CCl3 OH Na OH NH2 no partial NH3 6 c Provide the conditions needed to carry out the following transformation O OH O OH HO HO O O OH OH OH no partial H2 Pd C Pt Ni Rh Ir etc also OK 6 HO HO O O OH OH OH Page 4 IV 41 points A Picric acid was the first high explosive used in artillery shells its use as an explosive dates back to 1885 However picric acid can react with shell casings to form metal picrates which are unstable and unsafe A related compound TNT largely replaced picric acid as a high explosive between WWI and WWII Name O2N HO NO2 O2N Picric Acid O2N H3C NO2 O2N TNT a Indicate which compound TNT or Picric Acid has shorter carbon nitrogen bonds and provide a single resonance form to best explain your answer Be sure to include all nonbonding electrons and formal charges if as necessary O resonance form O N Compound with shortest carbon nitrogen bonds circle one Picric Acid TNT 4 if abbreviation NO2 is used for nitro groups attached by single bond Otherwise no partial H O O O O N N O H O N O O alternative correct answers O N O O H N O O 8 N O O O N O b Provide the reagents needed to complete the following transformation which is used in the synthesis of picric acid O O N HO ok if SO3 also present 1 H2SO4 2 HNO3 3 if steps reversed ok if H2SO4 also present 5 O2N HO SO3H B Draw the lowest energy chair conformation of molecule 4 Clearly indicate the directionality for all of the H and non H substituents on carbons 1 3 and 5 that are drawn on the structure below You do not need to draw in the H atom substituents on carbons 4 and 6 H2N H3CH2C Molecule 4 OH H H CH3 C5 C4 C6 C3 C1 C2 H CH3 NH2 OH H H3CH2C chair shape 3 connectivity 3 stereochemistry 3 lowest energy conformation 3 CH3 H H3C H lowest energy chair form of molecule 4 12 C Answer the following questions about molecule 5 shown below H3C H3C OCH3 O Molecule 5 CH3 CH3 a How many atoms in molecule 5 can …