Reactions Involving 1-Silyl-1-vinylcyclopropanes

2 Reactions Involving 1-Silyl-l-Vinylcyclopropanes 4.3.2.1 Synthesis Involving 1 -Metallo-1- Vinylcyclopropanes 

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 

4 Diels-Alder Reactions Involving AUylidene Cyclopropanes 

Allylidene cyclopropanes proved to be particularly reactive dienes especially if used as one of the partners in the Diels-Alder reaction They differ in that 

214) maleic and fumaric diesters maleic anhydride maleimide 

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The method has been extended to the preparation of 4-cyclohepteneones, such as karahanaenone (8) (equation II). In this case the reaction involves reaction of isobutyraldehyde with a mixture of cis- and fra . -l-lithio-2-methyl-2-vinylcyclopropane (4) followed by oxidation with pyridinium chiorochromale to give a mixture of ketones (5). Silylation and thermal rearrangement us before lead to (7) the ketone (8) is obtained on desilylation. 

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