Reaktionen mit Phosphinalkylenen, XL. Eine Aufbausequenz für Acetylene aus Aldehyden

Reactions with Phosphine Alkylenes, XL. A Sequence for the Preparation of Acetylenes Starting from Aldehydes Reaction of aldehydes 1 with CBr4/P(C6H5)3 gives rise to formation of 1,1‐dibromoolefins 2 which are converted by treatment with butyllithium into the lithium acetylides 7. On the other side, aldehydes 5 are transformed by Wittig reaction into olefins 3 which are hydroborated to give trialkylboranes 9. Reaction of 7 + 9 followed by treatment with I2 yields acetylenes 11.