CHM 252 Organic Chemistry II
Homework #4, Spring 2008
Due: Friday, April 25, 2008 by 5:00 pm
Problem #1:
Complete the following reactions by providing the structures for A-G.
Problem #2:
Give the product of the following reaction sequence and explain your answer. Be sure to show the complete mechanism of the reaction.
Problem #3:
Give the principal organic product expected when (Z)-3-hexen-2-one reacts with each of the following reagents.
(a) HBr
(b) Benzyltriphenylphosphonium bromide (ylide)
(c) Br2 in CCl4
(d) LiAlH4, then H2O
(e) HCN in water, adjust to pH of 10
(f) Et2Cu-Li+, then H3O+
(g) LDA and then add in (R)-2-ethyl-2-methylpentanal
(h) Ethylene glycol, HCl (catalyst)
(i) n-Butyllithium in THF, then H3O+
(j) mCPBA
(k) 1,3-cyclopentadiene
(l) H2SO4, H2O followed by NaOCH3 and 1-bromobutane
(m) H2SO4, H2O followed by Na2Cr2O7, H2SO4, H2O
(n) NaSCH2CH3 followed by NaOH (aq)
(o) 2-methyl-3-oxocyclohexanone in the presence of NaOCH2CH3/ethanol followed by KOH (aq) and heat.
(p) phenylhydrazine with acid catalyst
(q) LDA and benzyl bromide
(r) Br2, H2O
(s) phenylmagnesium bromide in ether, then H3O+
Problem #4:
Compound A (C8H8O; 1H NMR in CDCl3 d 7.7 (m, 2H), 7.3 (m, 3H), 2.5 (s, 3H); IR 1700 cm-1 (strong)) reacts with iodine under basic conditions to generate compounds B and C. Compound A also reacts with molecular bromine under acidic conditions to yield compound D, which subsequently undergoes a reaction with sodium cyanide in DMF to give compound E. Sodium borohydride reduction of compound E yields compound F, a hydroxyl nitrile of the formula, C9H9NO. Acid hydrolysis of this compound gives compound G, which when reacted with acidic ethanol yields compound H (C11H14O3). Compound H can be mildly oxidized using PCC to generate compound I, which upon treatment with sodium ethoxide in ethanol followed by reaction with ethyl bromide, saponification with NaOH (aq), acidification using aqueous HCl and gentle heating, spontaneously decarboxylates to yield compound J (a ketone with formula C10H12O). Provide the structures for compounds A-J.
Problem #5:
Synthesize the target molecule show from the given starting material. Your additional sources of carbons must not exceed 3 carbon atoms per reagent, unless (of course) you employ benzene.
Problem #6:
Provide a complete step-by-step mechanism for EACH of the following reactions.