Reactions of Vinyl Azides

This review is designed to demonstrate the versatility of vinyl azides in organic reactions. The reactive azide function is susceptible to thermolysis, photolysis, cycloadditions, and attack by nucleophiles and electrophiles. The neighboring double bond accentuates the reactivity of the azide function and provides additional intramolecular pathways for reaction. Last but not least, the presence of an appreciable electron density at the β-vinyl carbon makes this class of compounds comparable with enamines in their reactions with electrophiles and 1,3-dipoles.     

Reactions of Halogen Azides

Until recently, the explosive nature of halogen azides made these compounds unsuitable for preparative uses and greatly impeded investigation of their physical properties. Reactions of ClN₃ and BrN₃ with metal halides, metal carbonyls, and organometallic compounds to from metal azide halides, nitride halides, carbonyl azide halides, and alkylmetal azides were reported only very recently. The stability relationships of the halogen azides are discussed.     

Intramolecular and Intermolecular Schmidt Reactions of Alkyl Azides with Aldehydes

Despite recent advances in the use of alkyl azides in ring expansion reactions of ketones, there has been little work done on the corresponding chemistry of aldehydes. In the present study, the Lewis acid-promoted reactions of alkyl azides with aldehydes were studied in both intermolecular and intramolecular contexts. The intramolecular reactions of azidoalkyl aldehydes in which the azide and carbonyl groups were separated by 2-5 carbons were examined. Although the examples having the shortest tether failed (3-azidopropanals), each of the other systems gave good yields of either NH-substituted lactams (resulting from hydride migration in the initially formed azidohydrin adduct) or formamides (alkyl migration). The product formed was dependent on the chain length of the starting azido aldehyde. The intermolecular reactions were less efficient, requiring TiCl₄ promotion for even moderate yields, and in each case gave mixtures of products resulting from hydride and alkyl migration.     

Nitrene Adducts with Oxygen in the Photooxidation Reactions of Organic Azides

The photooxidation of organic azides and the photochemical reduction of nitro compounds include the formation of a common intermediate: the adduct of a nitrene with oxygen. The ground state of the adduct is singlet; the singlet–triplet gap is small and equals 80.2 or 56.7 kJ/mol for HNOO or C₆H₅NOO, respectively. Arguments for the involvement of singlet molecular oxygen, atomic oxygen, hydroxyl radicals, and dioxaziridines in these reactions were given.     

Reaction of Isonitriles with Dibenzoylacetylene Leading to Furan and Difuropyran Derivatives

A mixture of an isocyanide and dibenzoylacetylene in dry CH₂Cl₂ undergoes a smooth addition reaction at ambient temperature to furnish 3‐[5‐(alkylimino)‐3,4‐dibenzoyl‐2‐phenylfuran‐2(2H)‐yl]‐ 1‐phenylprop‐2‐yn‐1‐ones (1 : 2 adduct) and {2,5‐bis(alkylimino)‐4,7,8a‐triphenyl‐5H‐difuro[2,3‐b:3′,4′‐e]pyran‐3(8aH)‐yl}(phenyl)methanones (2 : 2 adduct). Single‐crystal X‐ray analyses conclusively confirmed the structures of the adducts.     

Reactions of Phosphorus Sulfides with Organophosphorus Substances

Abstract

We have found that the reactions of P4SIo and 1,3,2,4-dithiadiphosphetane-2,4-disulfides with phosphites, phosphonites, phosphinites, amidophosphonites, amidophosphinites, trithiophosphites, dithiophosphonites and thiophosphinites proceed under mild conditions via the previous formation of products containing the P(S)-S-P structural fragment which were isolated by column chromatography.     

Reactions of Organic Azides with Half‐sandwich Complexes of Iridium: Preparation of Mono‐ and Bis(imine) Derivatives

Imine complexes [IrCl(η⁵‐C₅Me₅){κ¹‐NH=C(H)Ar}{P(OR)₃}]BPh₄ ( 1 , 2 ) (Ar = C₆H₅, 4‐CH₃C₆H₄; R = Me, Et) were prepared by allowing chloro complexes [IrCl₂(η⁵‐C₅Me₅){P(OR)₃}] to react with benzyl azides ArCH₂N₃. Bis(imine) complexes [Ir(η⁵‐C₅Me₅){κ¹‐NH=C(H)Ar}₂{P(OR)₃}](BPh₄)₂ ( 3 , 4 ) were also prepared by reacting [IrCl₂(η⁵‐C₅Me₅){P(OR)₃}] first with AgOTf and then with benzyl azide. Depending on the experimental conditions, treatment of the dinuclear complex [IrCl₂(η⁵‐C₅Me₅)]₂ with benzyl azide yielded mono‐ [IrCl₂(η⁵‐C₅Me₅){κ¹‐NH=C(H)Ar}] ( 5 ) and bis‐[IrCl(η⁵‐C₅Me₅){κ¹‐NH=C(H)Ar}₂]BPh₄ ( 6 ) imine derivatives. In contrast, treatment of chloro complexes [IrCl₂(η⁵‐C₅Me₅){P(OR)₃}] with phenyl azide C₆H₅N₃ gave amine derivatives [IrCl(η⁵‐C₅Me₅)(C₆H₅NH₂){P(OR)₃}]BPh₄ ( 7 , 8 ). The complexes were characterized spectroscopically (IR, NMR) and by X‐ray crystal structure determination of [IrCl(η⁵‐C₅Me₅){κ¹‐NH=C(H)C₆H₄‐4‐CH₃}{P(OEt)₃}]BPh₄ ( 2b ).     

Dabco-Catalysed Reactions of Salicylaldehydes with Acrylate Derivatives

Treatment of salicylaldehydes with acrylate derivatives in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) has been shown to afford both coumarin and chromene derivatives, and factors influencing the product distributions have been investigated.     

Metal-Free Direct Hydrosulfonylation of Azodicarboxylates with Sulfinic Acids Leading to Sulfonylhydrazine Derivatives

A metal-free direct hydrosulfonylation protocol of azodicarboxylates with sulfinic acids has been developed for the construction of sulfonylhydrazine-1,2-dicarboxylates at room temperature. This methodology provides an efficient and practical approach to prepare various sulfonylhydrazine-1,2-dicarboxylates in good to excellent yields, which has the advantages of operation simplicity, environmental friendliness, high atom economy, and mild reaction conditions.     

Reactions of Bicyclo[2.2.1]hept-5-ene-2,3-dicarboximides with Aromatic Azides

Reactions of N-substituted bicyclo[2.2.1]hept-5-ene-endo-2,endo-3-dicarboximides with o- and p-nitrophenyl azides, as well as with p-nitrophenylsulfonyl azide and p-toluenesulfonyl azide, afforded the corresponding substituted dihydrotriazole (from aryl azides) and arylsulfonylaziridine derivatives (from sulfonyl azides). The exo orientation of the nitrogen-containing cyclic fragments (in keeping with the Alder rule) and endo orientation of the imide ring were confirmed by analysis of the IR and ¹H and ¹³C NMR spectra. The molecular structure of one of the products was examined by X-ray analysis.     

Reactions of Sulfenamides with Compounds of Trivalent Phosphorus

Chloro-dimethylamino-phenyl-p-tolylthio-phosphonium chloride 2 , dimethylamino-diphenyl-p-tolylthio-phosphonium chloride 3 , bis(diethylamino)-dimethylamino-p-tolylthiophosphonium chloride 4 and tert-butyl-dimethylamino-phenyl-p-tolylthio-phosphonium chloride 5 were prepared by the reaction of N,N-dimethylamino-p-tolylsulfenamide 1 with PhPCl₂, Ph₂PCl, (Et₂N)₂PCl and ^tBu(Ph)PCl, respectively. The reaction of N,N′-dimethyl-N,N′-bis(trimethylsilyl)urea 9 and N-methyl-N′-phenyl-N,N′-bis(trimethylsilyl)urea 10 with phenylsulfenyl chloride 6 or p-nitrophenylsulfenyl chloride 8 furnished the N-arylthio-N,N′-diorgano-N′-(trimethylsilyl)-ureas 11 – 14 . The reaction of 11 – 14 and of the previously known compounds 15 and 16 with MePCl₂, ClCH₂PCl₂, ^tBuPCl₂ and PhPCl₂ resulted in the formation of the 2-arylthio-2-chloro-1,2,3-triorgano-1,3,2λ⁵-diazaphosphetidin-4-ones 17 – 26 . 1,3-Dimethyl-2-(1,1,1,3,3,3-hexafluoro-2-propoxy)-2-phenyl-2-phenylthio-1,3,2λ⁵-diazaphosphetidin-4-one 29 and the 2-arylthio-1,3-dimethyl-2-(p-nitrophenoxy)-2-organyl-1,3,2λ⁵-diazaphosphetidin-4-ones 30 – 32 were obtained in the reactions of compounds 17, 24 and 27 with 1,1,1,3,3,3-hexafluoro-2-propanol or p-nitrophenol in the presence of triethylamine. The reaction of compound 21 with thiophenol in the presence of triethylamine resulted in a mixture of products, from which 1,3,4,5,7-pentamethyl-1,3,5,7-tetraaza-4λ⁵-phosphaspiro[3.3]heptan-2,6-dione 33 was isolated. The identity and structure of all the new compounds were established by ¹H-, ¹³C- and ³¹P-NMR spectroscopy and by elemental analysis. A possible mechanism of reaction of sulfenamides with compounds of trivalent phosphorus is discussed. For the compounds 5a, 32 and 33 X-ray structure analyses were conducted. The cation of compound 5a involves four-coordinate phosphorus (essentially tetrahedral geometry) and is a rare example of a P–S single bond in such a system (P–S 207.37(9) pm). In 32 the geometry at phosphorus is distorted trigonal bipyramidal, with axial positions occupied by oxygen and nitrogen atoms. In the spirophosphorane 33 the geometry at phosphorus is intermediate between trigonal bipyramidal and square pyramidal, with essentially planar four-membered rings.     

Regioselective Synthesis of Phosphonylated Sugars from Reactions of Glycals with Diphenylphosphenium Cation

Reaction of methyl 4,6‐di‐O‐acetyl‐2,3‐dideoxy‐d‐erythro‐hex‐2‐enopyranoside 1 with two equivalents of diphenylphosphenium cation at 0°C gave the 1‐phosphonylated 2‐enopyranosides 3α and 3β as major products. Similarly, reaction of diphenylphosphenium cation with tri‐O‐acetylglycal afforded the same products in a similar ratio. In contrast, a reaction with tri‐O‐benzylglucal at reflux temperature of dichloromethane afforded the 3‐phosphonylated sugar 13 as a major product. These reactions may proceed via stable allyl cations.     

Triphenylphosphonium Trifluoromethanesulfonate in Reactions with Epoxy Derivatives

Russian Journal of Organic Chemistry -     

Interaction of Phosphorus Acid Derivatives with Polycentric Nucleophiles

Abstract

In the present communication we consider some data on the chemical interaction of various phosphorus reagents witn unsaturated organic substrates having “n” or “Π” centres, some pyranes and guanidines.     

Reactions of Furfuryl Alcohol Derivatives with Benzeneselenenyl Chloride

During studies on furanoselenium compounds of furfuryl alcohol derivatives with benzeneselenenyl chloride^1,2 two new rearrangements were observed (Schemes I and II).