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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aromatization). An unseparable 1:2 mixture <strong>of</strong> 14a and <strong>of</strong> 5-phenylthio-3-<br />
methoxyphthalate was obtained when a benzene solution <strong>of</strong> the starting materials<br />
was stirred at −10 °C for 16 h and when the reaction was quenched by addition <strong>of</strong><br />
THF and hydrochloric acid (5%). The reaction presumably proceeds by cycloaddition<br />
to give intermediate A. Subsequently, cleavage <strong>of</strong> the silyl ether under the acidic<br />
work-up conditions and subsequent elimination <strong>of</strong> methanol from the intermediary<br />
hemiacetal afforded product 14a.<br />
MeO 2C<br />
PhS<br />
3a<br />
+<br />
13<br />
OSiMe 3<br />
OMe<br />
CO 2Me<br />
1) neat<br />
-78 to 20 °C<br />
20 h<br />
2) NH4Cl, H2O<br />
MeO2C MeO2C SPh<br />
A<br />
35<br />
OMe<br />
SPh<br />
MeO2C OH<br />
CO2Me 14a (77%)<br />
OSiMe 3<br />
NH4Cl, H2O<br />
Scheme 12. Possible mechanism <strong>of</strong> the formation <strong>of</strong> arene 14a<br />
The cyclization <strong>of</strong> DMAD with 3-arylthio-1-trimethylsilyloxy-1,3-butadienes 3a,d-m,p<br />
afforded the novel 5-arylthio-3-hydroxyphthalates 14a-l in moderate to good yields<br />
(Scheme 13, Table 5). A wide range <strong>of</strong> products could be successfully prepared. The<br />
best yields were obtained for products derived from dienes containing an electron-
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