Tetrahedron letters

Transition metal catalysed synthesis of tetrahydro derivatives of [5]-,[6]-and [7] helicene

IG Stará, I Starý, A Kollárovič, F Teplý, Š Vyskočil…

Index: Stara, Irena G.; Stary, Ivo; Kollarovic, Adrian; Teply, Filip; Vyskocil, Stepan; Saman, David Tetrahedron Letters, 1999 , vol. 40, # 10 p. 1993 - 1996

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Citation Number: 110

Abstract

Tetrahydro analogues of [5]-,[6]-and [7] helicene have been easily prepared by intramolecular [2+ 2+ 2] cycloisomerization of appropriate triynes under CpCo (CO) 2PPh 3 or Ni (cod) 2PPh 3 catalysis. This nonphotochemical methodology allows enantioselective synthesis of a helical skeleton employing the Ni (cod) 2 (S)-(−)-MOP catalytic system. On reaction with DDQ, tetrahydro [5] helicene was transformed to [5] helicene.