A New Mild Method for the C‑Acylation of Ketone Enolates. A Convenient Synthesis of β‑Keto-Esters, -Thionoesters, and -Thioesters

A new method for ketone enolate C-acylation is described which utilizes alkyl pentafluorophenylcarbonates, thiocarbonates, and thionocarbonates as the reactive acylating agents, and MgBr₂·Et₂O, DMAP, and <i>i</i>-Pr₂NEt as the reagents for enolization. A wide range of ketones have been observed to undergo clean C-acylation via this protocol

Synthesis of the C(7)–C(22) Sector of (+)-Acutiphycin via O‑Directed Double Free Radical Alkyne Hydrostannation with Ph₃SnH/Et₃B, Double I–Sn Exchange, and Double Stille Coupling

Herein a new double O-directed free radical hydrostannation reaction is reported on the structurally complex dialkyldiyne <b>11</b>. Through our use of a conformation-restraining acetal to help prevent stereocenter-compromising 1,5-H-atom abstraction reactions by vinyl radical intermediates, the two vinyl­stannanes of <b>10</b> were concurrently constructed with high stereocontrol using Ph₃SnH/Et₃B/O₂. Distannane <b>10</b> was thereafter elaborated into the bis-vinyl iodide <b>9</b> via O-silylation and double I–Sn exchange; double Stille coupling of <b>9</b>, O-desilylation, and oxidation thereafter furnished <b>8</b>

The Absolute Configuration for Inthomycin C: Revision of Previously Published Work with a Reinstatement of the (3<i>R</i>)‑Configuration for (−)-Inthomycin C

Stereochemical evidence is presented to demonstrate that (−)-inthomycin C has (3<i>R</i>)- and not (3<i>S</i>)-stereochemistry. Careful reappraisal of the previously published work− now indicates that the Hatakeyama, Hale, Ryu, and Taylor teams <i>all</i> have synthesized (−)-(3<i>R</i>)-inthomycin C. The newly measured [α]_D of pure (−)-(3<i>R</i>)-inthomycin C (98% ee) is −7.9 (<i>c</i> 0.33, CHCl₃) and not −41.5 (<i>c</i> 0.1, CHCl₃) as was previously reported in 2012