Exam 5 - Summer 11 (Key)

Exam 5 - Summer 11 (Key) - Fifth Hourly Examination...

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Unformatted text preview: Fifth Hourly Examination Chemistry S-20 August 1, 2011 8:{0 Name: - 9:20 a.m. lGv Section TF: lmportant Notes: 1. This exam consists of 8 problems on 8 pages, plus this cover sheet, and one page for scratch work at the end of the exam. 2. All answers must be wriften in the spaces provided. Do not write anything in red ink. Answers wriften on the back of a page will not be graded. Anything written on the scratch page will not be graded. 3. You are allowed to use a set of molecular models for this exam. Problem Score t12 t12 Total Score: 114 t12 t12 t12 t12 t14 / 100 1 Name: kV 1. Each of the following transformations can be carried out in three or fewer steps. Fill in the reagents required for each step. lf a step is not needed, please put an "X" through that step. o a) ed 1. LDA (l.t 2. ,.-Bf 3 N".tsttq, o b) ---A 1. [)A "q,^iu.) [eOp1 o (O.q elu.iv.) 2. HaX 3. lL, Na.OH ')*ou*"o o 1. CrnO=, ,HO pqn&'vr.r- c) 2. 3. d)*"Ab oo NaoR (c=t{,tlc,€fl NaSE NoO t- Mc (2"{"t"\ t.k*% 2. 3. f,JaOH, Hr.o 11*, A 0-sA tu o t12 Name: KeV 2. Fill in each box with the slngle major organic product of the indicated transformation. For full credit, your answer must conform to the molecular formula given. Be sure to indicate the correct stereochemistry if it is relevant! o o 0"o a) NaOH * Mol. form. C1oH14O ot{ 1. H3O+ b) H"'.--l-..+,- Ho HO oH 2. H2NNHz, KOH, A d Mol. form. C6H14O5 (You may ignore stereochemistry) o o o,*-A* Mol. form. C11H1iNO4 o d) $ 1. Me2CuLi o /)-2.\ 3. H+ workup Mol. form. CeH16O3 t12 3 Keu Name: 3. Consider the following transformation. egb--t= a) *,*.^-A1, Provide a complete mechanism to account for this transformation. Y ou may rgnore stereochemistry for this"r*"d-",fo* part. I v \ GL,o*. t lsn 6tE L-Aou, +tF e{ fr**o9n (E4 L,0Ft.- b) \Mren a ferf-bu$l group is added to the ring, there are two possible diastereomers as shown below. lt is observed that Diastereomer A reacts much more rapidly in this reaction than does Diastereomer B. Provide a concise frontier molecular orbital (FMO) explanation for this observation, including clearly-drawn and labeled chair diagrams and "cartoon" orbital drawings. l*" #', reacts much more quickly than Diastereomer A &as+c^t'r.cr A , Diastereomer B J{. AJ lcr,,q fri. -s o 'c^-{d p.re"Hy + rwrrl ,jte ^ , l*F-T * yW+fu'c-tr l"h.t i;t;J^fi,lT ,? {-, "".1 "g",,*t1^,\ j€- T tr-t3fy(t st".^l'rl*). AJo s^cL *t.f ir fossitl<ir^ &'-s-{<=uy e. B. t14 l(et 4. Provide a complete curved-arrow mechanism for all steps of the following multistep transformation. o t 9oo t-'*8" .-:OO I >s,,. b Ho-_:og? J, cxfu,,. Br t12 Kev 5. Provide a complete curved-arrow mechanism for all steps of the following multistep transformation. 0{ o 1. NaH, 7* 2. NaOEt, EIOH :HO 0- I o o * ,roA, \ ffi, \t/ )>.+ r:Q@ \ \ fa. H-oa L 0 + e+oLu *fu,oE? \ oE# H t12 (ey 6. Provide a complete synthesis of the following desired product from the indicated starting material. You may use any inorganic reagents, plus any organic reagents with eight or fewer carbons. You do not need to show any mechanisms. You may ignore stereochemistry. The best answer will require seven or fewer total steps. Starting Material: oo AA"* plus any organic compounds with eight or fewer carbons o r.Co,pd" A * Naoe+ Z ' ll+ ufl* o Ph -4. o rr.AH NJE* tu)\A,p\ (C,r+,r.r.,e+) Ai:''o Pt ='\pt F, ttro fr*, A (C..,1*'.t A) o +6 nA\Aph (z=H,r..,ED I u^ou v o rA.' n^ A-Lr^ j r.r^cv, *o1a Desired Product t12 7 Name: lGv 7. Provide a complete synthesis of the following desired product. You may use any inorganic reagents, and any acyclic organic compounds. You do not need to show any mechanisms. You may ignore stereochemistry. The best answer will require five or fewer total steps. Starting Materlal: anyAGYCLIG organic compounds .-4.^6'* o #ffi- o #" I I u^oe+- v "d*A' \ n ^g* (?=w,*-,eD Jr* 0 ft\" 1. UA|H{ Z. tt+ "{,r., 'oH Desired Product t12 Kez 8. Provide a complete synthesis of the following desired product. You may use any inorganic reagents, and organic compounds containing five or fewer carbons, as well as DCC and Boc2O (Boc anhydride), You may use either solution-phase or solid-phase (Merrifield resin) chemistry to receive full credit. You do not need to show any mechanisms. The best answer will require ten or fewer total steps. startingMaterial:. r "?"1ffI;J#::1"' *,*t' *'-, tu&4ron &.ro (c*1*r r) DCC, and Boc2O Heou , I I t/ rre (S.t;tr- ,^+"d ?!.) --t t(Sol*ticn- J*'" o -\ a\rHg' t-oa$+", '?.^oAfAy"-52 @-"OY ' I I I I *, J r I o,Dcc I c-a*. Dcc , I J* th+e) t*oAp+fi+,.. OY I I o H+ crf,. I I lJoOt, ttq TFA I *+-,o-@ tt)/*u I I Htr I t OY Desired Product t14 ...
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