Page 312 - Advanced Organic Chemistry Part B - Reactions & Synthesis

284 3.11. Indicate the product to be expected under the following reaction conditions:

CHAPTER 3 (a) H C O 2 CCH 3
3
Functional Group O , CH Cl 2
2
Interconversion
by Substitution, OH + –
7 7
3
Including Protection and CH 3 O NH O SC H
Deprotection CH 3
25°C, 3h
(b) OTBDMS OCH POCl 3
S 3 (cat)
CH 2 OH + CH 2 CCH 3
S CH Cl 2
2
CH 3
O O
(c) Pd, cyclohexadiene
PhCH OCNHCH 2 C N ethanol
2
HO C
2
NH
(d) H 2 ClCO 2 CH 3
C CO H + PhCH O
2
CH SH
2
(e) CH(SCH CH )
2
3 2
H C OH O
CuSO 4
H C OH + CH CCH 3 formula is C H O S
3
13 26
4 2
HO C H
HO C H
CH 3
3.12. A reagent that can introduce benzyloxycarbonyl protecting groups on amino
groups in nucleosides is prepared by allowing benzyl chloroformate to react first
with imidazole and then with trimethyloxonium tetrafluoroborate. What is the
structure of the resulting reagent (a salt) and why is it an especially reactive
acylating agent?
3.13. Triphenylphosphine reacts with peroxides to give intermediates that are related
to those formed in the Mitsunobu reaction. The following reactions are examples:
O O O O
THF
PhCOOCPh + Ph P PhCOCPh + Ph P O
3
3
70°C
77%
O O 80% THF O O
20% EtOH
C H
PhCOOCPh + Ph P PhCOCPh + Ph P O + PhCO 2 2 5
3
3
70°C
O 71% < 2%
PhCOOC(CH ) + Ph P PhCO C(CH ) + (CH ) C CH 2 + PhCO H
3
3 3
2
3 2
3 3
2
41% 52%
What properties of the intermediates in the Mitsunobu reaction are suggested by
these reactions?
3.14. The scope of the reaction of Ph P-Cl CCOCCl with allylic alcohols has been
3 3 3
studied. Primary and some secondary alcohols, such as 14A and 14B, give good