The Pagodane → Dodecahedrane Concept-Shorter Routes, Higher Yields

Martin Bertau; Jürgen Leonhardt; Andreas Weiler; Klaus Weber; Horst Prinzbach

doi:10.1002/chem.19960020517

The Pagodane → Dodecahedrane Concept-Shorter Routes, Higher Yields

Chemistry. 1996 May;2(5):570-579. doi: 10.1002/chem.19960020517.

Authors

Martin Bertau¹, Jürgen Leonhardt¹, Andreas Weiler¹, Klaus Weber¹, Horst Prinzbach¹

Affiliation

¹ Chemisches Laboratorium der Universität, Institut für Organische Chemie und Biochemie Albertstr. 21, D-79104 Freiburg (Germany) Fax: Int. code +(761)203-5987.

PMID: 29178234
DOI: 10.1002/chem.19960020517

Abstract

Two variants of the "S_N 2 route" from pagodanes (A, B) to functionalized dodecahedranes (D, F) and particularly dodecahedradienes (E) offer considerable improvements in the number of operations (from nine to five to three) and yields (e.g., for diester F from 55-65 to 70-75 to 85-91%). Key steps are the regio- and stereospecific introduction of four to six bromine substituents into dimethyl pagodane-4-syn,9-syn-dicarboxylate (1 b) and a highly complex (thirteen bond-breaking/bond-forming events in four participating structures). yet very convenient (one-pot operation) and extremely efficient (nearly quantitative) transformation of secopagodane to bissecododecahedradiene with complete stereocontrol in transannular CH₂ functionalizations. The prohibitively low kinetic acidity of "caged" hydrogens has so far only been overcome with the recently reported P₂ F reagent (Schwesinger). Further improvement of the overall economy of the pagodane → dodecahedrane scheme has been achieved by efficiently channeling a byproduct of the pagodane synthesis (ca. 10%) back into the S_N 2 track.

Keywords: cage effects; dodecahedranes; organic synthesis; pagodanes.