A Highly Efficient Synthesis of the FGH Ring of Micrandilactone A. Application of Thioureas as Ligands in the Co-catalyzed Pauson−Khand Reaction and Pd-Catalyzed Carbonylative Annulation

Abstract

The functionalized FGH ring system of micrandilactone A was successfully constructed in high selectivity and good yields. The key reactions in our strategy are the Co-thiourea-catalyzed stereoselective, intramolecular Pauson-Khand reaction and Pd-thiourea-catalyzed stereoselective, intramolecular annulation. [structure: see text]

Transition metals in organic synthesis: Highlights for the year 2005

“…TEMPO [990] and dodecyl methyl sulfide [991] were shown to promote Pauson-Khand reactions. A catalyst system of dicobalt octacarbonyl-tetramethylthiourea and carbon monoxide was reported [992] and used in synthesis toward micrandilactone [993]. Palladium catalyzed Pauson-Khand reactions using tetramethylthiourea and carbon monoxide [994].…”

“…Related reactions of propargylic amines gave (E)-␣-haloalkylidene-␤-lactones [1039]. An intramolecular palladium-catalyzed alkoxy-palladation carbonylations-lactonization of an 1-ene-1,6-diol was used to prepare micrandilactone [993]. Palladium catalyzed a carbonylative cyclization of 5-ynoates to give ␥-alkylidene-␣,␤-unsaturated ␥-lactones (Eq.…”

Four New Dibenzocyclooctadiene Lignans from Schisandra rubriflora

“…The location of the two MeO groups was further confirmed by the ROESY correlations (Fig. 2) observed between HÀC(4) and HÀC (6), and between HÀC(9) and HÀC (11). The only difference to gomisin R was the variety of the substitution pattern in the cyclooctadiene ring.…”

Thiourea and Selenourea and Their Applications

“…Thiourea-based sensors are generally designed to recognize anion through an intermolecular hydrogen bonding [73][74][75][76][77] salts are easily generated in one step from anilines. Regiospecific carbonylate annulation mediated by palladiumthiourea complex generates benzo[b]furan-3-carboxylates or diversified flavones (Scheme 42) [78][79][80][81][82].…”