A Nonoxidative Sequence for the Preparation of 1,2-Diketone Derivatives Using Aldehyde and Organometallic Building Blocks.

This study investigates a synthetic sequence for the preparation of 1,2-diketone products. The sequence avoids oxidative conditions and instead employs reliable transformations including the Horner-Wadsworth-Emmons and addition of Grignard reagents to -methyl--methoxy (Weinreb) amide intermediates. The reaction sequence is suitable for the synthesis of nonsymmetric aliphatic and aryl substituted derivatives.

Synthesis of Pyrrolopyrazinones by Construction of the Pyrrole Ring onto an Intact Diketopiperazine.

This study reveals an alternative sequence for the synthesis of compounds that contain the pyrrolodiketopiperazine structural motif. Starting with a diketopiperazine precursor, a mild aldol condensation precedes pyrrole annulation and bicyclic ring fusion. The derived intermediate aldol condensation products, which bear either a protected carbonyl or a functionalized alkyne, can be cyclized to the pyrrolodiketopiperazine by protic or gold Lewis acid catalysis.