1 -Aryl-2- -2-propen-1 ones

Isoxazole-3-carbaldehyde has been obtained as a minor product from the reaction of acetylene with a mixture of nitric oxide and nitrogen dioxide (61JOC2976). Although 3-aryl-4-formylisoxazoles have been synthesized in good yields from the reaction of benzonitrile Af-oxides with 3-(dimethylamino)-2-propen-l-one (71S433), the parent member of the series, isoxazole-4-carbaldehyde, has never been reported. It may possibly be obtained by the addition of fulminic acid to 3-(dimethylamino)-2-propen-l-one. 

Various alkyl- and aryl-substituted [3]radialenes could be prepared from 1,1-dihaloal-kenes using organometallic pathways. Hexamethyl-[3]radialene (25), the first [3]radialene to be synthesized, was obtained in a very low yield by treatment of l,l-dibromo-2-methyl-1-propene (22) with butyllithium8,9. The lithium carbenoid 23 and the butatriene 24 are likely intermediates of this transformation (Scheme 2), the former being the source of an unsaturated carbene moiety which is transferred onto the latter. However, the outer double bonds of 24 are more readily cyclopropanated than the central one. 

It has been found that treatment of propiophenone with an excess amount of bromobenzene gives rise to l,2,3-triphenyl-2-propen-l-one (Eq. 11) [43]. In this reaction, a-arylation, unsaturation via -hydrogen elimination, and Heck-type arylation occur successively. From the reaction of butyrophenone is obtained the corresponding triarylated product (Eq. 12). The reaction sequence involves a-arylation, unsaturation via p-hydrogen elimination, two times vinyl-ogous arylation (y-arylation), and double bond isomerization. It should be noted that a,p-unsaturated carbonyl compounds are generally arylated at their y position (Eqs. 13 and 14) [54-56]. 

These same compounds (149 R = aryl) have also been prepared from o-hydroxychalcones and ethylenediamine <88MI 906-01 >. 2,3-Dihydro-5,7-dimethyl-l,4-diazepine is obtained in 56% yield on heating 4-phenylsulfonyl-3-penten-2-one with ethylenediamine at 100 °C in the absence of solvent <85JHC405>. This reaction provides an alternative to the vinamidinium route to 5,7-disubstituted-1,4-diazepines described above. The phenylsulfonyl groups of 2,3-bis(phenylsulfonyl)-l-propene (150) both activate the double bond to Michael addition and behave as a leaving group. These... 

Enantioselective imidation of alkyl aryl sulfides with A -alkoxycarbonyl azides as a nitrene precursor is effected by using (OC)Ru(salen) complex as catalyst. The steric and electronic nature of the Af-alkoxycarbonyl group strongly affect the enantioselectivity and the reaction rate. In a systematic and well-executed study of ligand effects on Lewis-acid-catalyzed Diels-Alder reaction, it has been shown that the attachment of aromatic a-amino acid ligands to copper(II) ions leads to an increase in the overall rate of the Diels-Alder reaction between 3-phenyl-l-(2-pyridyl)-2-propene-l-one (Din) and cyclopentadiene... 

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