Page 892 - Advanced Organic Chemistry Part B - Reactions & Synthesis

868 Scheme 10.1. Polyene Cyclizations

CHAPTER 10 CH 3
1 a CH O CH
3 2
Reactions Involving HCO H
2
Carbocations, Carbenes, CH CH CH CH
and Radicals as Reactive CH OH 2 2 2 >50%
Intermediates 3 CH
3
CH CH
2 b 3 1) CF CO H H C H 3
H 3 C 3 2 3 OH
–78°C
CH 2) LiAlH CH H
3 4 3 52%
C(CH ) H
3 2
CH 3 H C CH 3 CH 3
3
OH
O
3 c CH 3 H C CCH 3
3
CH 3 CF CO H,
2
3
3
C ethylene H C H
H 3
HO carbonate,
H
CH , –25°C 65%
HCF 2 3
H
4 d
CH 3 CH 3
CH SnCl4
H C CH 3 CH
3
3
CH CH NO 2 3
3
3
H CH 3 CH 3 0°C
O CH 3 H CH 3
CH HO ~20%
3 CH
CH 3 3
5 e O O
CH 3 BF ×OEt 2 H 3 C
3
O CH 3 Et N, –78°C HO
3
CH OCH Ph H
2
2
PhCH OCH 2 CH 3 25–35%
2
6 f
OTBDMS O
CH AlCl
3 2
H
–94°C
HO
O 84%
7 g F H
F CF 3 CO H
2
CH Cl , 8 14
Si(CH ) 2 2
3 3 –70°C
H
OH 65–70%
8 h 12 13 18 22
CH AlCl
3 2
CH Cl 17
2 2
–78°C H
HO 41%, 1.5:1 mixture of 12,13–18,17
O H and 13,18–17,22 dienes.
(Continued)