CHM 1321 Assignment 7 Answers - Université d'Ottawa

CHM 1321Assignment 7 AnswersSome questions may have more than one answer. For most questions, only one possible solution is presented. If you arenot sure if one of your answers is correct please check with your TA or myself.1) Predict the major product of the following reactions:a)1) O 32) PPh 3O+Ob)1) O 3O O O++2) CH 3 SCH 31) O 3Oc) 1-methylcyclohexene2) CH 3 SCH 3OOd)1) O 32) CH 3 SCH 32OOe)OsO 4OHOHf)2 KMnO 4NaOHHOHOOHOHHO+HOOHOHg)OsO 4OHOHh)mCPBAOi) mCPBAOa)b)c)d)e)f)Oj)mCPBA2) Propose efficient methods to achieve the following transformations (some may require more thanone step):OH2) H 3 O + OHOsO 4OH1) mCPBAOH2) H 3 O + OH1) NaOCH 3OHBr 2) OsO 4OHmCPBAOOsO 4OHOH1) mCPBA OH1

3) Predict the outcome of the following:a)H 2Pd/Cb)H 2Pd/Cc)D 2Pd/C4) Account for the following observation by drawing a mechanism. What is responsible for theregioselectivity in this reaction?HDDOCH 3 OH O OOHOorHHnot formedHOOOHHOthis carbocation isstabilized byresonance5) Compound A is a degradation product of the antibiotic vermiculine. The structure of A wasconfirmed by transforming A into B (C 11 H 18 O 4 ) which could also be prepared by the ozonolysis of C(C 11 H 18 O 2 ), a commercially available material. Compound C reacts with 1 equivalent of bromine togive D (C 11 H 18 Br 2 O 2 ). Assign structures to compounds B, C and D.OOOHO-HOOAOOCH 3H 2A B1) O 3 CPd/C2) PPh 3Br 2DCCl 4C 11 H 18 Br 2 O 2OOAOOCH 3H 2Pd/CO1234C 11 H 14 O 4 C 11 H 18 O 4 C 11 H 18 O 2OCH 31O5 6OCH 31) O 3 2O2) PPh 334B6O5 CC 11 H 18 O 2C11 H 14 O 4C 11 H 18 O 4BrBr2CCl 4OBrOCH 3D2C 11 H 18 Br 2 O 26) N-Bromosucciminide (shown below) is a source of electrophilic bromine (Br+). When 1-methylcyclohexene reacts with N-Bromosucciminide in the presence of fluoride ions, an additionreaction occurs.

ONBrOa) Draw a mechanism for the reaction and predict the regiochemistry of the addition.b) Draw one of the enantiomers of the product in the chair conformation.c) Draw the same enantiomer in the other possible chair conformation.d) What are the configurations of the stereocentres in the product shown in parts b and c?a)OBr NBr NFOOOb)FBrFBrc)BrFd) S FS Br7) Give the products of the following reactions and give mechanisms to show how they are formed:O1) NaBH 4a)HH 3 CO2) H 3 O +H 3 COB(OR) 3H 3 COb)OO BH 3O BH 3HHHHHH 3 COHH BH 3 CO3repeat 3XHOHO B(OR) 3O B(OR) 3HH HHHHHH 3 COH 3 COOR1) NaBH 42) H 3 O +OOBH 3OBH 3HHHHHHBH 3repeat 3XB(OR) 3OHHHHO B(OR) 3H HHO B(OR) 3HHR3

c)O1) NaBH 4OHBH 32) H 3 O + repeat 3XOHBH 3OHBH 3B(OR) 3OHHOHB(OR) 3HOHB(OR) 3ROOHd)1) NaBH 42) H 3 O +OOBH 3O BH3HBH 3repeat 3XB(OR) 3e)OHOO B(OR)3H H1) NaBH 4OH2) H 3 O +O B(OR)3ROOBH 3O BH3HBH 3repeat 3XOHO B(OR)3HHO B(OR)34R

f)O1) MeMgBr2) H 3 O +OHMeOMgBrOMgBrMgBrOHH 2 OMgBrOHOHO1) MeMgBrOHg)2) H 3 O +MeOMgBrOMgBrMgBrOHH 2 OMgBrOHOH8) Predict the major products of the following reactions.Bra)MgEt 2 OMgBrb)ClMgEt 2 OAMgClCH 3 OHBHc)BrMgEt 2 OAMgBrOOMgBrBd)BrMgEt 2 OAMgBrOBOMgBre)ClMgEt 2 OAMgClOBOMgClf)BrMgEt 2 OAMgBrOOMgBrB5

9) Propose methods to accomplish the following transformations (most require >1 step):Note: for many of these questions there is more than one solutiona) HOb)HOOSO OCH 3 SO 2 ClbaseBrNaBrOHMgEt 2 OH1) 2) H 3 O +OOHBrMgOHOHO 1) MeMgBr1) O 32) CH 3 SCH 3OOHOH2) H 3 O + 1)c)d)e)f)OOHOBrMgBrOHHBrMg2) H 3 O +OHOOH1)BrMgBrHBrMgH2) H 3 O +OHmCPBA1) CH 3 CH 2 CH 2 CH 2 MgBrO2) H 3 O +OHO HO PhPhPhH 2 SOH 2 SO HO Ph1) PhCH 2 MgBr4 4HOH 2 O2) H 3 O +6

10) 1-(1-Phenylcyclohexyl)piperdine is a Veterenary anesthetic that is sold illegally as PCP. Aresearcher was studying the phychotropic side-effects of the drug by preparing and testing analogs.She performed the following reactions and noted the observations shown below.N1-(1-phenylcyclohexyl)piperdineHOorHOCCl 3 CO 2 HN 3 N 3NaN 336 % 46 % 18%a) Draw the two starting materials in the chair conformation in which the tert-butyl group islocated in the equatorial position. Which is more stable and why?a)OHOHmore stablelarge Ph group is equitorialb) Draw a mechanism to explain her observation that the two starting materials gave the sameproducts in the same amounts.HOorHOCCl 3 CO 2 HH 2 OorH 2 ONaN 3N 3 N 3Addition of N 3-gives S N 1S N 1N 3HRemoval of Hgives E136 %46 %E118%11) Propose a synthesis of the following using any starting materials containing no more than 6 carbons.7

ORetrosynthesisOOHMgBrOSynthesisMgBrOOMgBrOMgBrHHOHHMgBrOH 2 OOH 2HmCPBAO12) Determine the structures of compounds A through G.OHO1) CH 3 MgIAH 2 SO 42) H 3 O + C 6 H 12 O heatBC 6 H 10H 2Pd/C1) O 3H 2 SO 4GC 10 H 16H 2 SO 4heat2) PPh 31) MgheatDOH C 6 H 12 OBrEHBrmCPBAFC 10 H 18 O 2)C 5 H 9 BrOOH 3) H 3 O +1) CH 3 MgI2) H 3 O +CC 5 H 8 OO8

13) Point out all of the flaws in the following incorrect Grignard reactions.a)BrOH1) Mg2)H3) H 3 O + OHOOHOH group in original materialwill give acid/base reaction withthe Grignardb)O1) MgOc)BrOOH2) HO3) H 3 O +OHOH1) CH 3 CH 2 MgBr2) H 3 O +OHC=O group in original materialwill react with the Grignard asit is formedOH group in original materialwill give acid/base reactionwith the Grignard. Thisreaction will happen fasterthan the desired displacementprocess9