Tetrahedron letters

Macroring contraction methodology. 6. transannular diels-alder reaction of the 14-members (E, E, E)-trienone

T Takahashi, Y Sakamoto, T Doi

Index: Takahashi, Takashi; Sakamoto, Yasuharu; Doi, Takayuki Tetrahedron Letters, 1992 , vol. 33, # 24 p. 3519 - 3522

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Citation Number: 24

Abstract

In both exo and endo transition states, the dominant conformation of A-ring takes the chair form because its boat conformation has the severe strain repulsion between the vinyl methyl and C 3 -methylene (steroidal numbering) groups. On the other hand, the C-ring has two possible chair and boat conformations within 1.26 Kcal/mol. ... The macrocyclic enone 6 was prepared in the following way. ... Satisfactory 1 H NMR and IR properties were obtained.