Cationic Rhodium(I)/Bisphosphane Complex‐Catalyzed Isomerization of Secondary Propargylic Alcohols to α,β‐Enones

Abstract

We have determined that hydrogenated cationic Rh(I)/ bisphosphane complexes are highly active catalysts for the isomerization of secondary propargylic alcohols to α,β-enones. A kinetic resolution of secondary propargylic alcohols proceeded with moderate selectivity with [Rh((R)-BINA-P)]OTf as a catalyst. Mechanistic studies revealed that the isomerization proceeds through intramolecular 1,3-and 1,2-hydrogen migration pathways. The isomerization of propargylic diol derivatives was also investigated, which revealed

New Synthesis of Furans: the Rhodium‐Catalysed Carbonylative Addition of Arylboronic Acids to Propargylic Alcohols/ Cyclisation Sequence

“…[8b] 2,5-diphenylfuran [19] and 2-phenyl-5-(p-chlorophenyl)furan as well as 2-phenyl-3-methylfuran [20] are known products, the 1 H and 13 C NMR spectra obtained for these compounds were in accordance with the reported data.…”

Catalytic [2+2+1] Cross‐Cyclotrimerization of Silylacetylenes and Two Alkynyl Esters To Produce Substituted Silylfulvenes

“…[11b-e] and the cationic rhodium(I) complex, affords (alkenyl)rhodium B and this compound reacts with another 2 to generate (dienyl)rhodium C. Subsequent intramolecular carborhodation to the silyl-bound triple bond affords (fulvenyl)rhodium As the cationic rhodium(I) complexes are effective catalysts for the E/Z isomerization of conjugated carbonyl compounds, [14] the isomerization of the initially formed (E)-3 would furnish (Z)-3. Alternatively, protonation of intermediate B affords cross-dimerization product 4.…”

Sequential Hiyama Coupling/Narasaka Acylation Reaction of (E)‐1,2‐Disilylethene: Rapid Assembly of α,β‐Unsaturated Carbonyl Motifs

“…The isomerisation of secondary propargylic alcohols to α,β-enones was recently developed by Tanaka and co-workers using a cationic rhodium(I)/BINAP complex, which gave good yields and selectivity. [28] However, substrate limitation was reported with phenyl-and the highly coordinating 2-pyridyl-substituted alcohols, which led, respectively, to a complex mixture of products and no reaction. Satisfyingly, 12b and 12o could be prepared by our coupling sequence in 86 and 70 % yields, respectively (entries 7 and 16).…”