The Pagodane → Dodecahedrane Concept-Shorter Routes, Higher Yields

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Polycyclic Hydrocarbons

Background:

• Pagodanes serve as precursors to complex polycyclic hydrocarbons like dodecahedranes.
• Previous synthetic routes to functionalized dodecahedranes were lengthy and low-yielding.
• Efficient functionalization of "caged" hydrogens remained a significant challenge.

Purpose of the Study:

• To develop improved synthetic methodologies for accessing functionalized dodecahedranes and dodecahedradienes.
• To streamline the S_N 2 route from pagodanes, reducing operational steps and enhancing overall yields.
• To address challenges in stereoselective functionalization and the synthesis of complex polycyclic structures.

Main Methods:

• Regio- and stereospecific bromination of dimethyl pagodane-4-syn,9-syn-dicarboxylate.
• A one-pot transformation of secopagodane to bissecododecahedradiene.
• Utilizing the P₂ F reagent to overcome kinetic acidity limitations of "caged" hydrogens.
• Recycling a byproduct from pagodane synthesis back into the S_N 2 pathway.

Main Results:

• Reduced the number of synthetic operations from nine to three.
• Increased yields for key intermediates, such as diester F, from 55-65% to 85-91%.
• Achieved a highly efficient, nearly quantitative, and stereocontrolled one-pot conversion of secopagodane.
• Demonstrated successful functionalization of "caged" hydrogens using the P₂ F reagent.
• Improved overall synthetic economy by reintegrating a pagodane synthesis byproduct.

Conclusions:

• The optimized S_N 2 route offers a substantial advancement in the synthesis of functionalized dodecahedranes.
• The methodology enables more efficient and higher-yielding access to complex polycyclic cage compounds.
• This work provides a more economical and practical approach to dodecahedrane derivatives.