Terminal alkynes, incompatibilities with

One limitation of this methodology is that unprotected terminal alkynes are incompatible with the strongly basic ethyl zinc reagents required for this reaction. Iivinghouse and coworkers found that a similar Ti(IV)tetra-aryloxide/cyclohexylmagnesium chloride system catalytically cycloisomer-ized dienes to methylenecyclopentanes 63 with the formation of some reduced product 64 (Eq. 8) [35]. 

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