One-Pot Synthesis of Chiral Allenes Mediated by Decahydroquinoxaline Scaffolds.

We report a direct and efficient one-pot strategy for the synthesis of highly enantioselective (R)-allenes using 1-alkynes and aromatic aldehydes mediated by decahydroquinoxaline scaffolds. The reaction, promoted by ZnI2 in toluene at 120 °C, proceeds smoothly under mild conditions, affording chiral allenes with good yields (57-85% for aliphatic alkynes and 25% for the aromatic alkyne) and excellent enantioselectivities (83-96%) within 4 h. This method offers a straightforward and practical approach for constructing valuable chiral allene frameworks that are potentially useful in organic synthesis and medicinal chemistry. The use of decahydroquinoxaline scaffolds enables effective chirality transfer, making this protocol a promising tool for stereoselective transformation.