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List of used abbreviations - RosDok - Universität Rostock

List of used abbreviations - RosDok - Universität Rostock

List of used abbreviations - RosDok - Universität Rostock

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3a<br />

O<br />

OSiMe 3<br />

O<br />

OMe<br />

+ Me Me<br />

Cl 3TiO<br />

Me<br />

SPh<br />

7a<br />

SPh<br />

E<br />

TiCl4 _<br />

Me3SiCl O<br />

O<br />

Me<br />

OMe<br />

TiCl 4<br />

TiCl 4<br />

(2 equiv.)<br />

CH 2Cl 2<br />

_ 78 20 °C<br />

H 2O<br />

Scheme 7. Possible mechanism <strong>of</strong> the formation <strong>of</strong> 8a<br />

_<br />

23<br />

SPh<br />

O<br />

Me Me<br />

Cl<br />

Cl 3TiO<br />

Me<br />

8a (48%)<br />

F<br />

Me<br />

OMe<br />

_<br />

(Cl3Ti) 2O<br />

+<br />

TiCl3 SPh O<br />

OMe<br />

_<br />

Cl<br />

The cyclization <strong>of</strong> 1-trimethylsilyloxy-3-arylthio-1,3-butadienes 3a,d,f,g,i,k,o with 1,1-<br />

diacylcyclopropanes 7a-e, in the presence <strong>of</strong> TiCl4 or TiBr4, afforded the 5-haloethyl-<br />

2-(arylthio)benzoates 8a-x (Scheme 8, Table 3). Products 8b-d,g,i,j,l,o, derived from<br />

the unsymmetrical cyclopropanes 7b-d, were formed with very good regioselectivity.<br />

This can be explained by regioselective attack <strong>of</strong> the terminal carbon atom <strong>of</strong> diene 3<br />

onto the acetyl rather than the less reactive aroyl group <strong>of</strong> 7b-d.

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