Handbook of Functionalized Organometallics Applications in S

O
R1 R 2
(2.0 mmol)
O
CH3CH(ZnLn ) 2
(2.0 mmol)
β-TiCl3 (2.0 mmol)
THF
1
R R2
H3C n-C10H21 62%
O
13%
O
n-C 8 H 17 48%
n-C 11 H 23 CHO
R 3
63% (E / Z = 67 / 33)
Scheme 8.19 Alkylidenation of carbonyl compounds with gem-dizinc and b-TiCl 3.
O
R 1
OR 2
+ R 3 CHBr2 (1.0 mmol) (2.2 mmol)
Zn (9.0 mmol)
TiCl4 (4.0 mmol)
TMEDA (8.0 mmol)
R 1
R 3
OR 2
O
O
Ph OCH3 CH3CHBr2 Ph OCH3 CHBr2 86% (Z / E =92/8) 61% (Z / E = 90 / 10)
O
O
OCH CH
3 3CHBr2 90% (Z / E =94/6)
n-C4H9 O n-C5H1 CHBr2 52% (Z / E =92/8)
Scheme 8.20 Alkylidenation of esters with Zn±RCHBr 2±TiCl 4±TMEDA.
n-C 8H 17
n-C 8 H 17
O
SCH3 + CH3CHBr2 (1.0) (2.2)
O
+ CH3CHBr2 N
(1.0) (2.2)
Zn (9.0), TiCl 4 (4.0)
TMEDA (8.0)
n-C8H17 SCH3 94% (Z / E = 73 / 27)
Zn (9.0), TiCl 4 (4.0)
TMEDA (8.0)
H 3 C
n-C 8H 17
94% (E only)
8.2 gem-Dizincio Compounds
CH 3
Scheme 8.21 Ethylidenation of thioester and amide with Zn±CH 3CHBr 2-TiCl 4±TMEDA.
N
359