Metal-catalyzed cascade rearrangements of 3-alkynyl flavone ethers.

Metal-catalyzed cascade rearrangements of 3-alkynyl flavone ethers.

Organic letters (2013-04-12)

Yuan Xiong, Scott E Schaus, John A Porco

ABSTRACT

Metal-mediated rearrangements of 3-alkynyl flavone ethers are reported. The overall process involves 5-endo enyne cyclization to a platinum-containing spiro-oxocarbenium intermediate which may be trapped with methanol to produce spirodihydrofurans or further rearranged to afford either allenyl chromanediones or benzofuranones.

MATERIALS

Product Number

Brand

Product Description

520799

Sigma-Aldrich

Platinum black, low bulk density, ≥99.9% trace metals basis

298093

Sigma-Aldrich

Platinum, gauze, 100 mesh, 99.9% trace metals basis

444685

Sigma-Aldrich

Platinum, wire, diam. 2.0 mm, 99.9% trace metals basis

349321

Sigma-Aldrich

Platinum, foil, thickness 0.25 mm, 99.99% trace metals basis

349380

Sigma-Aldrich

Platinum, foil, thickness 0.1 mm, 99.9% trace metals basis

520780

Sigma-Aldrich

Platinum black, fuel cell grade, ≥99.9% trace metals basis

357375

Sigma-Aldrich

Platinum, wire, diam. 0.076 mm, ≥99.99% trace metals basis

327484

Sigma-Aldrich

Platinum, shot, ≤3 mm, ≥99.9% trace metals basis

205915

Sigma-Aldrich

Platinum black, black, powder, ≤20 μm, ≥99.95% trace metals basis

267244

Sigma-Aldrich

Platinum, foil, thickness 0.025 mm, 99.9% trace metals basis

349348

Sigma-Aldrich

Platinum, foil, thickness 0.127 mm, 99.99% trace metals basis

267821

Sigma-Aldrich

Platinum, wire, diam. 0.127 mm, 99.9% trace metals basis

349402

Sigma-Aldrich

Platinum, wire, diam. 0.25 mm, 99.9% trace metals basis

357359

Sigma-Aldrich

Platinum, wire, diam. 0.20 mm, ≥99.99% trace metals basis

303798

Sigma-Aldrich

Platinum, foil, thickness 0.05 mm, ≥99.9% trace metals basis

204048

Sigma-Aldrich

Platinum, powder (coarse), 99.99% trace metals basis

298107

Sigma-Aldrich

Platinum, gauze, 52 mesh, 99.9% trace metals basis

204013

Sigma-Aldrich

Platinum, powder, 99.995% trace metals basis

267163

Sigma-Aldrich

Platinum, wire, diam. 0.127 mm, 99.99% trace metals basis

327492

Sigma-Aldrich

Platinum, wire, diam. 1.0 mm, 99.9% trace metals basis

267155

Sigma-Aldrich

Platinum, sponge, ≥99.9% trace metals basis

327476

Sigma-Aldrich

Platinum, powder, ≤10 μm, 99.9% trace metals basis

267228

Sigma-Aldrich

Platinum, wire, diam. 0.5 mm, 99.9% trace metals basis

327433

Sigma-Aldrich

Platinum, foil, thickness 0.125-0.135 mm, 99.9% trace metals basis

357367

Sigma-Aldrich

Platinum, wire, diam. 0.10 mm, 99.99% trace metals basis

327425

Sigma-Aldrich

Platinum, foil, thickness 0.25 mm, 99.9% trace metals basis

267171

Sigma-Aldrich

Platinum, wire, diam. 0.25 mm, 99.99% trace metals basis

267236

Sigma-Aldrich

Platinum, wire, diam. 1.0 mm, 99.99% trace metals basis

685453

Sigma-Aldrich

Platinum, nanopowder, <50 nm particle size (TEM)

349356

Sigma-Aldrich

Platinum, foil, thickness 0.05 mm, 99.99% trace metals basis