Low-Valent Titanium Induced Carbonyl Coupling Reactions
Low-Valent Titanium Induced Carbonyl Coupling Reactions
Low-Valent Titanium Induced Carbonyl Coupling Reactions
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Amines. Amines are inert towards low-valent titanium and have been added in some reactions<br />
to improve yields[43].<br />
OHC<br />
N<br />
H<br />
23<br />
N<br />
H<br />
CHO<br />
TiCl 3/Zn<br />
3%<br />
Ether. All types of ethers are compatible to low-valent titanium. THF, DME and benzyl<br />
ethers[44] are used as solvents in these reactions without any reported adverse effects. Even<br />
silyl ethers are compatible[45].<br />
Halides. Halides substituted on aromatic nucleus appear to be compatible as illustrated by this<br />
example[46].<br />
Br<br />
CH 3<br />
O<br />
TiCl 3/Li<br />
25 26<br />
Br<br />
Sulfide. Not many cases have been reported and no problems were encountered with the<br />
following example[47].<br />
O<br />
27<br />
S<br />
O<br />
TiCl 4/Zn<br />
N<br />
H<br />
H<br />
N<br />
CH 3<br />
24<br />
CH 3<br />
N<br />
H<br />
H<br />
N<br />
S<br />
28<br />
Br<br />
67 %<br />
17
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