Structural Analysis of the Michael-Michael Ring Closure (MIMIRC) Reaction Products

Area of Science:

• Organic Chemistry
• Synthetic Chemistry

Background:

• Decalin and hydrindane frameworks are prevalent in natural products and pharmaceuticals.
• Efficient and stereoselective synthesis of these scaffolds remains a challenge.

Purpose of the Study:

• To develop a novel cascade reaction for synthesizing decalin and hydrindane derivatives.
• To investigate and elucidate the stereochemical outcome of the reaction.
• To explore the scope and limitations of the developed synthetic protocol.

Main Methods:

• A cascade reaction involving cyclohexanone/cyclopentanone enolates and methyl acrylate.
• Michael-Michael ring closure (MIMIRC) process.
• Analysis of relative stereochemistry using 1H NMR and X-ray crystallography.
• Conformational analysis supported by DFT calculations and NMR spectral simulations.

Main Results:

• Synthesis of decalin and hydrindane derivatives (2a-l) in 11-91% yield.
• Determination of relative stereochemistry at four stereogenic centers.
• Consistent stereochemistry observed at C-1 and C-8a, with variations at C-3 and C-4a.
• Validation of stereochemical assignments through computational methods.

Conclusions:

• The developed triple cascade reaction is a practical and efficient method for generating structurally diverse decalin and hydrindane derivatives.
• The study provides insights into the stereochemical control and limitations of the MIMIRC process.
• This protocol offers a valuable alternative for accessing complex polycyclic structures.