Lactonization oxidative

Cyclic compounds capable of undergoing ring opening (alkylene oxides, lactones, lactams, anhydrides, etc.). 

Hiroi et al. developed a new system for the oxidative lactonization of diols using acetone as cooxidant and catalyzed by the Cp lr complex bearing an... 

Oxidative lactonization of unsaturated diacids (9, 265). Further study of this reaction indicates that it is general and can be controlled to result in cts-addition of two carboxylic oxygens to the double bond. Two experimental conditions are satisfactory (I) treatment of the diacid in CHClj or CII3CN with a large excess of Pb(0Ac)4 and (2) treatment of the tetra-n-butylammonium salt of the diacid in CH3CN with 6 15 equivalents of PbfOAc).,. Yields by the latter procedure are generally higher. 

Coproporphyrin I synthesis, 816 Coronands classification, 919 metal ion complexes, 928,938 Corphins, 855 Coninoids, 983 Corrins, 871-888 demetallation, 882 deuteration, 879 electrophilic reactions, 879 metallation, 882 NMR, 878 nucleophilicity, 886 nucleophilic reactions, 879 oxidation, 879 oxidative lactamization, 880 oxidative lactonization, 880 photochemistry, 887 reactions, 879 at metal, 885 rearrangements, 879 redox chemistry, 888 spectra, 877 synthesis, 878 Corroles, 871-888 demetallation, 874 deuteration, 872 hydrogenation, 872 metallation, 874 reactions, 872 at metal, 875 redox chemistry, 876 synthesis, 871 Corticotropin zinc complexes medical use, 966 Cotton effect anils, 717... 

The cyclizations of halo acetals, introduced by Stork66 and Ueno,67 are among the most popular of all radical methods because the precursors are easy to prepare, the cyclizations are very rapid, and the products can be converted to a variety of different heterocycles. The conversion of (26) to (28 Scheme 17) illustrates the basic procedure.68 Standard bromoacetalization of an alcohol provides the precursor (27). After tin hydride cyclization and acidic oxidation, lactone (28) is formed in excellent yield with 97%... 

The iridium-catalyzed oxidative lactonization of 2-carbaldehyde benzylketones 778 forms isocoumarins in high yield (Scheme 205) <2005BML2583>. 

OXIDATIVE LACTONIZATION Dimethyl sulfoxide-Methanesulfonic anhydride. Lead tetraacetate. 

The retrosynthesis of Aara-e-viniferin (445) by Thomas et al. indicated that the y-butyrolactone (823) was a key intermediate, which later converted from the corresponding stilbene by manganese triacetate-mediated oxidative lactonization (Scheme 18) [407]. In subsequent papers, they described the FeCb-promoted tandem pericyclic synthesis of catechol analogs of restrytisol C. 3,4-Dimethoxy-12-acetoxy stilbene (824), which was synthesized by Heck coupling, was treated with FeCb to give the unnatural stilbene dimers 585 and 586 (Scheme 19) [288]. 

It is claimed that styrene/butadiene diblock polymers bring about an improvement in the hardness, strength, and processability of polybutadiene elastomers (27), as well as an improvement in the ozone resistance of neoprene rubber (28). Styrene diblock polymers have also been made with isoprene, a-methyIstyrene, methyl methacrylate, vinylpyridine, and a-olefins. Block copolymers of ethylene, propylene, and other a-olefins with each other have been made as well. Heteroatom block copolymers based on styrene or other hydrocarbons and alkylene oxides, phenylene oxides, lactones, amides, imides, sulfides, or slloxanes have been prepared. 

Oxidative dearomatization. The modification of a naphthol by oxidative lactonization is critical toward a synthesis of lactonamycin. Lead(IV) acetate fulfills this need. ... 

Oxidation. Lactone formation from lactols based on the (PPhjljRuClj-mediated hydrogen transfer to benzalacetone is efficient. The application of this technique to the process of elaborating a dihydropyran unit into two carbon chains played a crucial role in a synthesis of akuammicine. ... 

Bayer-Villiger oxidation Lactones <99% Increased reactivity and selectivity 2006/[38]... 

The ability of A -heterocyclic carbenes to activate a,p-unsaturated carbonyl compounds via the formation of the corresponding Breslow intermediate, which plays the role of a homoenolate nucleophile, has also been applied to a cascade process involving a formal intramolecular Michael reaction/oxidation/ lactonization, leading to the formation of complex tricyclic carbon frameworks starting from a bifunctional substrate containing an enone and an a,p-unsa-turated aldehyde side chain linked to each other via a benzene tether (Scheme 7.82). The reaction involved a complex multistep mechanism which started with the activation of the enal by the catalyst, forming the Breslow intermediate, which subsequently underwent intramolecular Michael reaction and next the generated enol-type intermediate reacted intramolecularly with the... 

Scheme 7.82 Cascade intramolecular Michael reaction/oxidation/lactonization catalyzed by an iV-heterocyclic carbene.

Ammonium cerium(IV) sulfate Regiospecific Baeyer-Villiger oxidation Lactones from cyclic ketones... 

Suzuki T, Yamada T, Watanabe K, Katoh T (2005) Mdium-catalyzed oxidative lactonization and intramolecular Tishchenko reaction of 6-ketoaldehydes for the synthesis of isocoumarins and 3,4-dihydroisocoumarins. Bioorg Med Chem Lett 15 2583-2585... 

Suzuki T, Morita K, Ikemiyagi H, Watanabe K, Hiroi K, Katoh T (2006) Synthesis of the hemiacetal pheromone of the spined citrus bug biprorulus bibax utilizing an iridium catalyzed oxidative lactonization. Heterocycles 69 457-461... 

Suzuki T, Morita K, Matsuo Y, Hiroi K (2003) Catalytic asymmetric oxidative lactonizations of meso-diols using a chiral iridium complex. Tetrahedron Lett 44 2003-2(X)6... 

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