ChemInform Abstract: Copper‐Catalyzed Intramolecular Aryl‐Bicyclization of Diynes with Diaryliodonium Salts via Vinyl Cations.

A novel protocol for the synthesis of polycyclic compounds from linear diynes and diaryliodonium salts has been realized. The reaction proceeded through Cu-catalyzed arylation of alkynes to generate two vinyl carbocation intermediates that subsequently reacted with arene groups to form fused rings containing diene moieties.

Since the molybdenum and ruthenium carbene complexes 1a and 1b were discovered by Schrock and Grubbs in 1990 and 1992, synthetic organic chemistry has progressed with the use of these complexes as the catalyst for olefin metathesis. It was found that the ruthenium carbene complex was also effective for enyne metathesis, which occurs between an alkene and an alkyne. Intramolecular enyne metathesis gives various cyclic compounds having a 1,3‐diene moiety and cross‐metathesis of an alkene with an alkyne is a useful method for the synthesis of a compound having a diene moiety. Furthermore, dienyne metathesis, ROM of cycloalkenynes or tandem reactions of enyne metathesis have been developed. Using these various enyne metatheses, complicated natural products have been synthesized via novel routes. The syntheses of natural products and related compounds using enyne metathesis are described.

1. A study was made of the decomposition of diaryliodonium salts with antimony powder under various conditions. 2. A method was evolved for synthesis of organoantimony compounds, consisting of decomposing mixture of a diaryliodonium chloride and SbCl3 with antimony powder in boiling acetone. 3. On changing from diphenyliodonium chloride to diphenyliodonium iodide, yield of organoantimony compounds was lowered markedly.

A transition-metal-free synthesis of spiro compounds from 9H-fluoren-9-ols mediated by hypervalent iodine is reported. In this reaction, an unprecedented β-carbon elimination of tertiary alkoxyliodine(III) to form new diaryliodonium salts is proposed. The obtained phenol intermediates undergo oxidative dearomatization to furnish a class of oxo-spiro compounds. This domino reaction significantly increases the complexity of these molecules and shows excellent regio- and stereoselectivity.

Martín Fañanás‐Mastral

A transition‐metal‐free synthesis of spiro compounds from 9H‐fluoren‐9‐ols mediated by hypervalent iodine is reported. In this reaction, an unprecedented β‐carbon elimination of tertiary alkoxyliodine(III) to form new diaryliodonium salts is proposed. The obtained phenol intermediates undergo oxidative dearomatization to furnish a class of oxo‐spiro compounds. This domino reaction significantly increases the complexity of these molecules and shows excellent regio‐ and stereoselectivity.

1. A method was developed for the synthesis of organobismuth compounds via diaryliodonium salts. By this method we prepared the following compounds: triphenylbismuthine, tri-p-tolylbismuthine, tris-p-methoxyphenylbismuthine, tris-p-bromophenylbismuthine, tris-p-chlorophenylbismuthine, tris-p-nitrophenylbismuthlne, and bis[methoxycarbonyl)phenyl]bismuth chloride. 2. The decomposition of iodonium salts with bismuth powder with formation of organobismuth compounds occurs only in presence of bismuth trichloride. 3. It is suggested that the initial products of the decomposition of iodonium salts with bismuth are compounds of the types ArBiCl2 and Ar2BiCl. 4. The decomposition of diphenyliodonium chloride, bromide, and iodide with bismuth powder was carried out in presence of BiCl3. In the case of diphenyliodonium iodide the yield of triphenylbismuthine was considerably lower than in the decomposition of diphenyliodonium chloride.

Synthesis and structural characterization of nitro-functionalized cyclic hypervalent iodine compounds

The Synthesis of Heterocyclic Compounds with Hypervalent Organoiodine Reagents

For Abstract see ChemInform Abstract in Full Text.

Catalytic synthesis of nonracemicP-chiral phosphine derivativesremains a significant challenge. Here we report Cu-catalyzed enantioselectivearylation of secondary phosphine oxides with diaryliodonium saltsfor the synthesis of tertiary phosphine oxides with high enantiomericexcess. The new process is demonstrated on a wide range of substratesand leads to products that are well-established P-chiral catalystsand ligands.

Copper-catalyzed cascade reactions between alkenes or alkynes and diaryliodonium salts form carbocyclic products in a single step. Arylation of the unsaturated functional group is proposed to form a carbocation intermediate that facilitates hydride shift pathways to translocate the positive charge to a remote position and enables ring formation via a Friedel-Crafts-type reaction.

Polycyclic hydrocarbon compounds exhibit a wide variety of biological activities, ranging from antiviral to Parkinson’s disease. Several structures such as the adamantanes have reached clinical status and are used therapeutically to treat, amongst others, neurodegenerative disorders such as Alzheimer’s. Polycyclics have also been utilised as carrier molecules to facilitate entry of drugs into the brain. The synthesis, molecular and crystal structure of a new polycyclic compound, 3-hydroxy-4-aza-8-oxoheptacyclo[9.4.1.02,10.03,14.04,9.09,13.012,15]tetradecane, are reported. NMR spectroscopy was applied for structure elucidation of the novel compound and a rearrangement mechanism is proposed for its formation. This compound crystallises in the orthorhombic system, space group Pbca (no. 61). The unit cell parameters are: a = 12.3763 (7), b = 11.6597 (6), c = 15.0539 (8) A, V = 2172.3 (2) A3 , and Z = 8 molecules in the unit cell. The reported structure was confirmed by X-ray analysis, which showed that the title molecules associate into centrosymmetric dimers via N–H···O hydrogen bonding. The synthesis and structure of a new polycyclic compound, 3-hydroxy-4-aza-8-oxoheptacyclo[9.4.1.02,10.03,14.04,9.09,13.012,15]tetradecane, are reported in this article.

The synthesis of polycyclic heteroaromatic compounds using the reaction of a quinone-methide, generated in situ, with an aromatic amine has been successfully extended using quinone-methides of coumarin and of pyridones. Preliminary studies with the benzenoid quinone-methide (33) have so far proved to give only low yields of the expected acridines. Generation of ‘quinone-methides’ in which the carbonyl is part of an amide group did not lead to polycyclic heteroaromatic compounds.

A general and straightforward new synthesis of polycyclic heteroaromatic compounds has been developed. In the synthesis a putative quinolone-quinone-methide is generated in the presence of an aniline. The ensuing reaction results in a polycyclic heteroaromatic product. In the most useful approach, a hemiacetal (25) is prepared in one step from the parent quinolone and this is heated in the presence of an aromatic amine to produce the polycyclic heteroaromatic compound in good yield. The regiospecificity of the reaction is the opposite to that expected in the Skraup synthesis with respect to the quinone-methide component. With respect to the aniline component, however, regiospecificity is the same as in the Skraup synthesis.