“…19) A recent interesting study reported by Nakao, Shirakawa, Hiyama, and coworkers showed that a stannylative benzannulation occurred by the Pd-catalyzed reaction of enynes (or enynes and diynes) with hexabutyldistannoxane (Chart 11). 20) Since it has been postulated that the cyclic allene (1,2,4-cyclohexatriene) was converted to the benzene ring or reacted as a nucleophile, 21,22) their results (stannylative benzannulation), combined with our results (benzannulation), might indicate the intermediacy of a strained allene such as 20 (Chart 12). The reaction was further expanded by Gevorgyan, Yamamoto, and co-workers to the corss-benzannulation reaction between conjugated enynes and diynes.…”