Taking diazo transfer to water: α-diazo carbonyl compounds from in situ generated mesyl azide

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Cascade reactions of nitrogen-and phosphorus-containing ylides with methyl diazoacetate and in situ generated diazocyclopropane

Reactions of pyridinium or phosphorus ylides with diazo esters are multistep processes. The first step is covalent bonding between the ylide C atom and the terminal N atom. This is followed by elimination of the ylide-forming molecule and successive addition of one or two ylide fragments. Depending on the nature of the starting reagents, this type of transformations leads to novel polyfunctional phosphorus ylides or, with pyridinium ylides, to polyalkyl 3,4(4,5)-diazaalkadienetri-or tetracarboxylates. A reaction of the in situ generated diazocyclopropane with methyl triphenylphosphoranylideneacetate stops at the first step, giving a cyclopropylazo-containing ylide. Reactions of the latter with acyl chlorides yield six-membered heterocyclic betaines with a triphenylphosphonium substituent. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 108–113, January, 2006.     

Total syntheses of zaragozic acids A and C by a carbonyl ylide cycloaddition strategy

A carbonyl ylide cycloaddition approach to the squalene synthase inhibitors zaragozic acids A and C is described. The carbonyl ylide precursor 8 was synthesized starting from di-tert-butyl D-tartrate (47) via an eleven-step sequence involving the regioselective reduction of the mono-MPM (MPM=4-methoxybenzyl) ether 48 with LiBH4 and the diastereoselective addition of sodium tert-butyl diazoacetate to alpha-keto ester 10. The reaction of alpha-diazo ester 8 with 3-butyn-2-one (40) in the presence of a catalytic amount of [Rh2(OAc)4] gave the desired cycloadduct 59 as a single diastereomer. The dihydroxylation of enone 59 followed by sequential transformations permitted the construction of the fully functionalized 2,8-dioxabicyclo[3.2.1]octane core 5. Alkene 79 derived from 5 serves as a common precursor to zaragozic acids A (1) and C (2), since the elongation of the C1 alkyl side chain can be attained by olefin cross-metathesis, especially under the influence of Blechert's catalyst (85).     

A facile synthesis of 1,7-dicarbonyl compounds via three-component Michael addition reactions

A convenient one-pot synthesis of 1,7-dicarbonyl compounds has been accomplished by a three-component Michael addition reaction of nitromethane with two unsymmetric α,β-unsaturated carbonyl compounds in the presence of a base.     

Unusual multiple insertion of diazo carbonyl compounds into (purin-6-yl)benzene derivative

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Extension of the Willgerodt-Kindler reaction: protected carbonyl compounds as efficient substrates for this reaction

Nitrogen derivatives of carbonyl compounds such as oximes, hydrazones, and semicarbazones were found to be excellent candidates for the Willgerodt-Kindler reaction. They can be used directly in a solvent-free reaction, under both classical and microwave conditions, to give the corresponding thiomorpholides in good yields.     

Novel cycloaddition reaction of [60]fullerene with carbonyl ylides generated from epoxides

The thermal reaction of [60]fullerene (C60) with the carbonyl ylides generated in situ from trans-epoxides to give C60-fused tetrahydrofuran derivatives has been investigated. The reaction of C60 with trans-2-benzoyl-3-aryloxiranes afforded only cis-products, while the reaction of C60 with 2-cyano-2-ethoxycarbonyl-3-aryloxiranes gave exclusively or predominantly cis isomers. The isomeric distributions of the latter reactions were drastically affected by the substituent on the phenyl ring.     

Oxidation of diazo compounds by triphenyl phosphite ozonide. Quenching of singlet oxygen by diazo compounds

The reaction of triphenyl phosphite ozonide with various types of diazo compounds results in their oxidation, which is accomplished by singlet oxygen (¹O₂) evolved during thermal decomposition of the ozonide. A decrease in the ionization potential of the substrate results in an increase in the overall rate constant of quenching of¹O₂. In the case of 9-diazofluorene, the main channel of¹O₂ quenching is physical quenching.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1567–1571, September, 1994.The work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 93-03-5231).     

Phosphonylated thiocarbonyl ylides from the reaction of aromatic thioketones with diethyl diazomethylphosphonates

The reaction of diazomethylphosphonates with aromatic thioketones at −65 °C to room temperature yields 2,5-dihydro-1,3,4-thiadiazole-2-phosphonates, which eliminates N₂ to give phosphonylated thiocarbonyl ylides as reactive intermediates. These sulfur-centered 1,3-dipoles undergo typical reactions of thiocarbonyl ylides, i.e., 1,3-dipolar cycloadditions, cyclodimerization, and electrocyclic ring closure, depending on the involved thioketone and, therefore, on the reaction conditions. In the case of the most reactive thiofluorenone, the phsophonylated thiocarbonyl methanide can be intercepted with thiobenzophenone, a phosphonodithioformate, and tetracyanoethylene. In the absence of such reactive dipolarophiles, cyclodimerization occurs to give the corresponding 1,4-dithiane.     

Stereoselective approach to conjugated enone oximes from aliphatic nitro compounds and sulfur ylides

A novel approach to conjugated enone oximes from aliphatic nitro compounds deals with double silylation of N,N-bis(silyloxy) enamines followed by a stereoselective reaction with an ester-stabilized sulfur ylide. The proposed mechanism involves the generation of labile nitrosoalkenes as intermediates, which react with the sulfur ylide to give target enone oximes.     

Dual reactivity of imidic carbonyl ylides in Rh(II)-catalyzed reactions of α-diazocarbonyl compounds with succinimide

Stabilization of imidic carbonyl ylides derived from α-diazocarbonyl compounds and succinimide occurs in two different ways: ylides from diazoesters experience a [1,4]-hydrogen shift to produce the corresponding O-alkylimidates while their analogues with at least one acyl group undergo [1,5]-electrocyclization yielding 1,3-dioxoles.