3,17-Dioxoandrost-4-en-4-yl acetate

Area of Science:

• Steroid chemistry
• Crystallography
• Computational chemistry

Background:

• The title compound, C(21)H(28)O(4), features a 4-acetoxy substituent on the steroid alpha face.
• Steroid structures exhibit diverse conformations influencing their properties and interactions.

Purpose of the Study:

• To characterize the structural and conformational properties of the title steroid compound.
• To investigate the nature of a specific C-C bond within the steroid B ring.
• To elucidate the intermolecular forces responsible for crystal cohesion.

Main Methods:

• X-ray crystallography was used to determine the solid-state structure.
• Quantum-mechanical ab initio calculations (molecular-orbital Hartree-Fock method) were employed to study the isolated molecule.
• Conformational analysis of the six-membered ring A was performed.

Main Results:

• The six-membered ring A adopts a conformation intermediate between a 1alpha,2beta-half chair and a 1alpha-sofa.
• A notably long Csp(3)-Csp(3) bond was identified in ring B of the steroid.
• Computational calculations successfully reproduced the observed long C-C bond.
• Crystal cohesion is primarily due to van der Waals interactions and weak C-H...O hydrogen bonds.

Conclusions:

• The study provides a detailed structural and conformational analysis of the title steroid.
• The presence of an elongated C-C bond in ring B is a significant structural feature.
• Intermolecular forces, including van der Waals interactions and hydrogen bonding, dictate the crystal packing.