Page 902 - Advanced Organic Chemistry Part B - Reactions & Synthesis

878 Scheme 10.2. Ene and Carbonyl-Ene Reactions

CHAPTER 10 A. Thermal Ene Reactions.
O O
Reactions Involving 1 a
Carbocations, Carbenes, 180°C Ph O
and Radicals as Reactive PhCH CH CH 2 + O
2
Intermediates 22 h 37–48%
2 b O O CO CH
O HO 2 3
CH 2 + CH O C 120°C CO CH 3
2
3
2
CO 2 CH 3 24 h
O O
B. Intermolecular Carbonyl-Ene Reactions. 97%
3 c CH 3 CH 3
BF 3
+ CH O
2
Ac O, CH Cl 2
2
2
CH C CH 2 H C CH 2 CH O CCH 3
3
2
2
2
4 d 84%
AlCl 3
(CH ) C CH + HC CCO CH 3 CH 2 CCH CH CHCO CH 3
2
2
2
3 2
2
25°C H C 61%
3
5 e OCH 3
) FeCl
CH(OCH 3 2
Ph 3
+ CH 2
5 mol % Ph
6 f 94%
C 2 H 5 OH
2
(i-PrO) TiCl 2
(C 2 H 5 ) 2 C CH + O CHCO C(CH ) CH 3
3 3
2
2
2
3 3
BINOL CO C(CH )
7 g OCH 3 CH 2 OCH 3 OH
Br CH O (CH ) AlCl Br
3 2
+
CH 3 O OSO CH 3 CH O OSO CH 3
3
2
2
Br Br
50%
C. Intramolecular Ene Reactions.
CO C H
C H
8 h CO 2 2 5 2 2 5
CHCH CH CH CH 2 280°C
2
2
CH 3 68%
(mixture of stereoisomers)
9 i O O CCF 3
2
(CH ) C CHCH 2 Et AlCl N CO C H
2 2 5
3 2
NCCF 3 –78°C CH CO C H
2 2 5
H O C
2 2 5 2
C 2 5 2 C(CO C H ) 3 CH CO C H
2 2 5 90%
CH 2 2
H H
j
10 TBDPSO
TBDPSO ZnBr 2
CH 3 CH(CO C H )
CO 2 C 2 H 5 2 2 5 2
CH 3 CO 2 C 2 H 5 90%
CH 3 CH 2
(Continued)