Dr. Spence CHEM24 1. Draw the following compoundsand indicate any stereocenterswith a (*). For thosethat have chiral centers,draw each enantiomerand label the configuration at each stereocenter(R or S). 3-methylhexane 2-chloropentane .-,K^ (s)r- \g,4./ v =( R ) CI LR) 2-methylhexane 3-chloropentane c\ --tA/ ) .\r"/ Determine(R) or (S) configurations at all chiral centersin the following molecules' )"-a' "4;s,* ";.4.", no* trz\ (K) Cs) Lr\ / qi" H NHr 9"", OH o ^ CS) Ho*sH3?H H-=oo they are For eachpair of molecules below indicate whether they are identical to each other or if enantiomirs of each other. For those that areidentical, draw the enantiomer. COrH OH ","$o" "T$"o," La) i c) culo, ! "le,ati ,enc.nL=hu"(4,1, tt 1 cr-f !"'cF3 ocH3 (sr ?"", F3cTcH3 CI (s) ErtarharYq{b CHE}i{24 Dr. Spence Considerthe molecule 1-bromo-3-chlorocyclohexane and answerthe following questions:(a) how many chiral centersare present? (b) what is the maximum number of stereoisomers possible?(c) draw all the possiblestereoisomers and label them A, B, C etc. (draw them as a hexagonusing wedge and dashto indicate stereochemistry).(d) define the configuration at all chiral centersand describethe relationshipbetweenall stereorsomers. (tr n"c- 9* o AJ--SC , ={( : I tr,nUv}itr ce"rttc), 2' . I mox fhrrur:'1,,'rf(1 Z chr(c^\ l ?r.ol-<reoot6 % :(fi) 0+9 frtQ = cl ci CI n Y) C O 9*t C*(7 of the following compound. To make it easier,useFischer Draw all possiblestereoisomers Cr{1or{ Cilrott L,$"uf C|"tlcil flo ftf "'^ "'t l{ r> ,TD ,IcH Cr{zorl rtlzoFf fNE,D CF\.pfl CdzPrl enan f*n^t(\ {,n850 Given the following information about a hypothetical molecule, calculate the Yooptical purity of a samplecontaining a mixture of the two enantiomerswith an optical rotation [a] of (a) +33.9' _l4.Io. Foi eachof thesemixturesalsoprovidethe relative o/oof eachenantiomer(%R and @16) and%S). a O-(R)-hypothetical lcrl=-32.0 d'^7\ l c | n.\'a c q#r*lvs =fia3'%e&,'l,to/"{qrvrttc % 9 =c t ; ' l % 4 , '4 , 3 (+)-(S)-hypothetical [6x]:+37.6 y- A'=&fi'75% , %S =7l,a5vb CHEM24 7. Dr. Spence For eachpair of moleculesbelow indicateif they are identical,enantiomersor diastereomers. (2R,3R,4R ,5R)-2,3,4,5-tetrachto.fii&?FofiW$,h,0*,r, )-2,3,4,S-tetrachlorohexane to[o"r\ r,al (*t2 ) evro.n\u'nrec> /\7cu.r ."\roH t ..*cH, t9ou t H. \-/ H 4cu, HrC. \ _ . / .CHr ,CH: : crt"'"'t]) l C H H H H l H3c-.|H3Cf Hrc* Br H l Br--]- cHs Br Br--|- H H l CHs . t c/rc{)lt(fbrv*6' i r drca)ftfrun^t(5 Draw all possible(stereoisomeric) productsfrom eachof the following reactions. Label the productsA, B, C, etc and describethe relationshipbetweenthe possibleproducts. Indicate which moleculesare chiral. Indicate if all productsform in equal amountsor unequalamounts. If the product mixture is expectedto be optically active check the box in front of the reaction. /"\/" n t \-,.-i l tu J V 1. OsOa 2. NaHSO3 I oil l _-l lrl6fl -+*o{ e-,-&crl o r+ v gnGfll"',)nEf > tr*t)'l chn6:{I €qvc,l cn*1,*rn$ Jra2hrturrt() 1. OsOa 2. NaHSO3 ,I--{,,, od / - [ , , ,e i 1 ff-ou I-\.J-- Vo7'v-tCh,<al o.rl ***:, "rn'*nTb l1 oH /l\-.\,,'\ /:d,, l Brz + Jiq>hrrtrnef> CIl-{w ry !7"th ch.(o'l aftJbflt> un€r1.tal R 9r- tt .+;z:( t \-5--; t tneS7; vlot Cht(al 7 'Lt''*'r W' n rt HBr Ch'r&l {nv,J ,J,olJ*'re,lrrcq5 a'rna{tfi Urreq,tul CHEM24 9. Dr. Spence While consideringthe cyclohexanering as a planarhexagon,draw an optically activeversionof 1,2,3,4,5,6-hexachlorocyclohexane. CI Cl rlt// ,r,,, Ci il $tt o*Lo h*ot c^ {la*rnt CIC 51nn'r'et*7 CI 10. For the first compoundin question8, identifu all pro-chiralsp'carbons. Are you looking at the Re faceor Si face? For the last compoundin question8, identify all pro-R positions. ((t fr*tt) gro'-ch'c'""1 /----t r ct l ta \ nQt'' r \\- gro-ch,{aI (9, h"e) * ; CH."'\t>l l l \ c>HfY 'f,^u R 'l*- ftt R 11. Circle the chiral centers in the following compounds. O OH O HO OH HO Prostaglandin E2 Cholesterol 12. Label with a "*" all the chiral centers in the following molecules. CH3 O N O NHCO2CH3 H C * * C H H3CSSS * C * H * C CH3 O O * H OR calecheamicin O cocaine 13. Identify the following pairs of compounds as enantiomers, diastereomers, or the same. Br Br diastereomers OH OH enantiomers Br Br HO OH diastereomers enantiomers 14. Identify the following pairs of compounds as enantiomers, diastereomers, constitutional isomers, or the same. a. diastereomers b. Br Br Br Br enantiomers HO OH 15. Identify the stereocenters in the following molecules and indicate whether they are R or S. H OH S R Cl NH2 HO S R S H OH S O not a stereocenter! 16. Using the tests for chirality we have learned, determine whether the following molecules are chiral. Determine the configuration (R or S) of any chiral centers in the molecules. Br R O R S CH3 OH chiral CH3 R OH S NH2 chiral OH S chiral HO OH S R CH3 achiral meso achiral no stereocenter achiral meso 17. Circle those molecules below that are chiral. OH Cl Cl O HO Cl Cl CH3 Cl CH3 18. Name the compound below. Be sure to include R,S designations. CH3 S-3-methylhexane 19. Determine the relationship between the following pairs of molecules: enantiomers, diastereomers, identical, or structural (constitutional) isomers. a. structural isomers Br Br b. diastereomers NH2 NH2 NH2 c. NH2 identical -- no chiral center OH HO d. enantiomers OH OH OH Br Br e. identical -- draw flat and see -- compound is meso CH3 CH3 f. OH CH3 H 3C identical -- meso OH OH OH OH