Anellated cycles

Scheme 6.52 Routes to anellated cycles and spirocycles via an overbred skeleton...

Vinylcyclopropanes are also suitable starting materials for the construction of five-membered cycles. The vinylcyclopropane rearrangement first discovered in the late 1950s191 192) immediately became the subject of intense mechanistic investigations 173 193,194) ancj was use(j for tjje CyCiopentene anelation 165.171 195 197> Gr cycloheptane anelation 198 200). This reaction was successfully applied to vinylcyclopropanes bearing a silyl moiety by Paquette 137,138> and was found particularly useful for the synthesis of vinylsilanes as part of a five-membered cycle. These have been in some cases subjected to electrophilic substitution 137,138 201 202) (Schemes 58 b, 65, 82-84). The ring expansion takes place when the thermolysis is conducted between 570° and 670 °C and only occurs with those compounds which do not possess 137)sterie inhibition around the carbon-carbon bond (Scheme 76, compare a and e). Incorporation of the double bond (Scheme 76, compare a and e). Incorporation of the double... 

Vinylcyclopropanes are also suitable starting materials for the construction of five-membered cycles. The vinylcyclopropane rearrangement first discovered in the late 1950s immediately became the subject of intense mechanistic investigations 193,194) fpj. jjjg cyclopentene anelation les. 171,195,197) cycloheptane... 

Scheme 4.19 Mechanistic cycle for the formation anellated benzothiophenes.

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