Synthesis of (4aR, 10aS)-(—)-8-Methoxy-1,1,4a-trimethyl-2-oxo-1,2,3,4,4a,9,10,10a-octahydrophenanthrene, an Optically Active Intermediate for the Synthesis of Diterpenes

The Usefulness of Phosphorus Compounds in Alkyne Synthesis

“…The preferred base for the one-pot synthesis of alkynes from aldehydes using 28 was found to be t-BuOK in THF. [158][159][160][161][162][163] The use of t-BuOK in THF at low temperature increases regiospecificity, reaction rate and yield. Thus, when a suspension of the (bromomethyl)triphenylphosphonium bromide (28) in anhydrous THF was treated with an excess of t-BuOK at low temperature, the yellow colored ylide 33 was formed then allowed to react with aldehydes (aliphatic, aromatic, and a,b unsaturated) to produce directly the desired alkynes 25 in moderate to excellent yields (36-100%) ( Table 3).…”