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Abstract
The cyclization reaction of 1-lithio-3-chloropropene derivatives to form cyclopropenes is a new approach to cyclopropene synthesis. The alkenyllithium species are obtained via the lithium-halogen exchange reaction of alkenyliodides which can be readily prepared from the corresponding propargyl alcohols. The silylated cyclopropene derivatives undergo several carbometallation and hydroalumination reactions in common with the chemistry of alkynes.
When 1-iodo-3-halopropene derivatives are treated with the enolate of N,N-diethylacetamide, the allylation product can be cyclized, following a lithium-halogen exchange reaction in which the alkenyllithium derivative forms, to cyclopentenones. This cycliacylation approach is a new method for preparation of cyclopentenones.
Another acylation approach discussed is the palladium-catalyzed acylation of organozinc reagents with acyl halides.
