Oxidant-Dependent Chemoselectivity in the Gold-Catalyzed Oxidative Cyclizations of 3,4,6,6-Tetrasubstituted 3,5-Dien-1-ynes

A distinct chemoselectivity in the
gold-catalyzed oxidative cyclization
of 3,5-dien-1-ynes was observed when 3,5-dichloropyridine N-oxide replaced 8-methylquinoline N-oxide
as the oxidant; the resulting cyclopentadienyl aldehydes were obtained
in good yields. The altered chemoselectivity is attributed to a prior
enyne cyclization in the presence of 3,5-dichloropyridine N-oxides. The use of N-iminopyridium ylide
enables a similar iminocyclization reaction to give cyclopentadienyl
imines efficiently. Our experimental data support a prior gold-catalyzed
cyclization of 3,5-dien-1-ynes to form gold carbene, followed by the
oxidation with N-oxide.

在金催化下，以3,5-二氯吡啶N-氧化物取代8-甲基喹啉N-氧化物作为氧化剂时，对3,5-二烯-1-炔的氧化环化反应表现出独特的化学选择性；所得的环戊二烯基甲醛以良好的产率获得。这种化学选择性的改变归因于在3,5-二氯吡啶N-氧化物存在下的预先进行的炔烃环化反应。N-亚氨基吡啶基叶立德的使用使得类似的亚氨基环化反应能够高效地生成环戊二烯基亚胺。我们的实验数据支持了3,5-二烯-1-炔在金催化下预先环化形成金卡宾，随后与N-氧化物进行氧化反应的观点。