Iodine-Catalyzed Cyclization of 3,4-Diphenylpenta-1,3-dienoyl Isocyanates 1

February 22, 2024

• Title:       

  Iodine-Catalyzed Cyclization of 3,4-Diphenylpenta-1,3-dienoyl Isocyanates 1

• Image Source:

  Substituent effects on the iodine-catalyzed thermal cyclization of 3,4-diphenylbuta-1,3-dienyl isocyanates: Mechanistic studies

• Mark:

  Scheme 1

• Associated context:

  To our surprise, not only 3,4-diphenylpyridin-2(1H)-ones 2 but also phenylnaphthalenes 3 or benzylidene-1H-indenes 4 were obtained by the iodine-catalyzed thermal cyclization of isocyanates,  generated in situ from the corresponding azides 5 (Scheme 1). We found that the cyclized product distribution depends on the substituents of the two phenyl rings, and a mechanistic rationale for the formation of 3,4-diphenylpyridin-2(1H)-ones 2, phenylnaphthalene 3, and benzylidene-1H-indene 4 is also presented.