pi-Conjugated conjoined double helicene via a sequence of three oxidative CC- and NN-homocouplings.
Dimerization of planarized diamine 2 using benzoyl peroxide gave dihydrazine 1 in about 70% yield; that is, three dehydrogenations (one CC- and two NN-homocouplings) and two ring closures were attained in one synthetic step. Dihydrazine 1 may be viewed as a chiral pi-conjugated conjoined double helicene, with two homochiral [5]helicene-like fragments, annelated in their mid-sections. A relatively high barrier of approximately 35 kcal mol-1 for inversion of configuration for one of the [5]helicene-like helices in 1 was found.
Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, USA.
Kouichi
K
Shiraishi
Andrzej
A
Rajca
Maren
M
Pink
Suchada
S
Rajca