A new synthesis of dienone lactones using a combination of hypervalent iodine(iii) reagent and heteropoly acid

A thermal decarboxylative Cloke–Wilson rearrangement of dispirocyclopropanes derived from para-quinone methides and bromo-Meldrum's acids: an approach to synthesize spirobutyrolactone para-dienones

An unprecedented approach to synthesize spirobutyrolactone para-dienones from para-quinone methides and bromo-Meldrum's acids has been developed.

Synthesis and Configuration of Natural Dracaenones

Several dracaenones were synthesized in enantiopure forms for the first time. The key chiral center at C-7 was installed with well-defined stereochemistry using either an Evans aldol condensation or a chiral oxidant-mediated asymmetric epoxidation, while and the critical oxidative coupling was achieved under the PIFA/PTA conditions. Comparison of optical rotations for the synthetic and natural samples allowed for unequivocal assignment of the absolute configurations of the natural dracaenones.

Development and application of new oxidation systems utilizing oxometalate catalysts

This review describes our recent efforts in the development and application of new oxidation systems utilizing oxometalate catalysts. The novel use of heteropoly acid (HPA), an acidic oxometalate catalyst, in hypervalent iodine-mediated oxidations provided an effective strategy to generate cation radical species that enables a variety of direct C-H functionalizations of aromatic compounds. This strategy brought a facile biaryl synthesis and new spirodienone syntheses in aromatic oxidation chemistry. Moreover, this strategy opens up a facile synthetic route to morphinandienone alkaloids. On the other hand, the use of oxometalate catalyst together with poly(N-isopropylacrylamide) (PNIPAAm)-based polymer in the development of new solid-phase catalyst provided a novel reaction system in water. Due to the characteristic temperature-responsive intelligence of PNIPAAm, this reaction system brought a remarkable acceleration of the reactivity and ease of catalyst recovering in catalytic oxidation that uses hydrogen peroxide or oxygen gas (O<inf>2</inf>) as primary oxidant. In addition, the recovered solid-phase catalyst could be used for consecutive reactions without any significant loss of its catalytic efficacy.

Synthesis of sulfur-sulfur bond formation from thioamides promoted by 2,3-dichloro-5,6-dicyanobenzoquinone

A mild and efficient synthesis of sulfur-sulfur bond formation from thioformanilides with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) is described. Functionality on the aromatic ring plays a key role in the formation of a sulfur-sulfur bond.

Hypervalent iodine reagents as a new entrance to organocatalysts

The catalytic utilization of hypervalent iodine reagents, largely in consideration of economical and environmental viewpoints, is a most attractive strategy due to their unique features as extremely useful oxidants, with mild, safe, and environmentally friendly characteristics. In addition to a system based on electrochemical reoxidation conditions, new reliable catalytic methods have emerged in recent years that can broaden the scope of the catalytic concept. For these contributions, a catalytic strategy is now available for performing many representative types of oxidative bond-forming reactions and alcohol oxidations mediated by hypervalent iodines, some of which even include key transformations for natural product synthesis. A suitable choice of terminal oxidants, e.g., m-chloroperbenzoic acid (mCPBA) or Oxone, for generation of active hypervalent iodine(iii) or (v) species from iodoarenes in situ, has led to recent rapid expansion in this field. This feature article highlights the historical background and the efforts made to realize the catalytic utilization of these reagents, especially with focus on iodine(iii).

Organoiodine-Catalyzed Oxidative Spirocyclization of Phenols using Peracetic Acid as a Green and Economic Terminal Oxidant

The use of peracetic acid as a green and economical terminal oxidant in fluoroalcohol solvents could provide a practical iodoarene-catalyzed oxidation of phenols to give spirodienones. Acetic acid and water were the only co-products and waste, and thus this catalytic approach utilizing fluoroalcohol media could simplify the reaction workup procedure for product isolation.

Improved procedure for the bimolecular oxidative amidation of phenols

Trifluoroacetic acid (TFA) is an effective promoter of the bimolecular Ritter-like oxidative amidation of 4-substituted phenols induced by PhI(OAc) 2 in MeCN. This suppresses the need for fluoroalcohol cosolvents, increases the yields, and facilitates isolation/purification procedures.