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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3-alkoxy-2-en-1-ones has been reported. 25 I have also recently studied the synthesis<br />
<strong>of</strong> 5-chloroethyl-2-(arylthio)benzoates by TiCl4-mediated domino ′[3+3] cyclization /<br />
homo-Michael′ reaction <strong>of</strong> 3-arylthio-1-trimethylsilyloxy-1,3-butadienes with 1,1diacylcyclopropanes.<br />
26 Herein, I provide a full account <strong>of</strong> this work. In addition, I<br />
report a comprehensive study related to the formal [3+3] cyclization <strong>of</strong> 3-arylthio-1trimethylsilyloxy-1,3-butadienes<br />
with 3-silyloxy-2-en-1-ones. The reactions reported<br />
provide a convenient approach to substituted 2-(arylthio)benzoates and<br />
thioxanthones which are not readily available by other methods.<br />
1.2 Result and Discussions.<br />
The reaction <strong>of</strong> β-ketoesters 1a-c with various thiophenols gave, following the<br />
procedure reported by Chan et al., 22,23 the 3-(arylthio)alkanoates 2a-k (Scheme 1).<br />
Deprotonation <strong>of</strong> 2a-k (LDA) and subsequent addition <strong>of</strong> Me3SiCl afforded, again<br />
following the procedure reported by Chan et al., 22,23 the 3-arylthio-1-silyloxy-1,3butadienes<br />
3a-m. The synthesis <strong>of</strong> 2a and 3a has been previously reported. Dienes<br />
3a-m proved to be unstable and had to be <strong>used</strong> directly after their preparation.<br />
R 1<br />
O<br />
1a-c<br />
R 1<br />
O<br />
OMe<br />
SAr<br />
ArSH<br />
3a-m (78-96%)<br />
i<br />
OSiMe 3<br />
OMe<br />
14<br />
R 1<br />
SAr<br />
O<br />
2a-k (76-94%)<br />
ii<br />
OMe<br />
Scheme 1. Synthesis <strong>of</strong> 3a-m (for R 1 and Ar, see Table 1); conditions: i, P4O10,<br />
CH2Cl2, 20 °C, 18 h; ii, 1) LDA, THF, −78 °C, 1 h; 2) Me3SiCl, −78 → 20 °C, 14 h