The reaction of N-isopropylallenimine (1) with several organic azides has been examined. Phenyl azide gives a mixture of triazole 3 and amidine 7. p-Toluenesulfonyl azide reacts with 1 to give only amidine 11; likewise tertbutyl and ethyl azidoformate give 12 and 13, respectively. Reaction of 12 with dry HCl gives N-isopropyl-P-lactamimide (14). The formation of the amidines and triazole 3 is rationalized in terms of triazoline intermediates.We have recently reported on the highly strained l-azaspiropentane s t r u c t~r e .~~~ This novel heterocyclic system was obtained by photochemical decomposition of triazoline precursors derived from thermal cycloaddition of phenyl azide t o methylenecyclopropanes (see eq 1). We now report on our attempts to extend this synthetic sequence to allenimine 1 in hopes of effecting conversion to a 1,4-diazaspiropentane (2).N-Isopropylallenimine (1) reacts slowly with phenyl azide to yield l-phenyl-5-(N-isopropylaminomethyl)-1,2,3-triazole (3) as the major product. The NMR of 3 shows, among other features, a sharp singlet for the aliphatic methylene group and a one-proton singlet a t 6 7.66 for the triazole ring proton. The uv spectrum of 3 displays a maximum a t 228 nm, supporting assignment as a &substi-tuted l-phenyl-1,2,3-triazole. Substitution at the 4 position of the triazole ring is known to shift the uv maximum of the parent l-phenyl-1,2,3-triazole (4) (248 nm) to longer wavelength, whereas substitution at the 5 position causes a shift to shorter ~a v e l e n g t h .~ l3C NMR confirms the 5-substituted l-phenyl-1.2,3-triazole structure for 3; the chemical shifts of the triazole and phenyl carbons of 3 and 4 are listed in Table I. The C-5 carbon of the triazole ring in 3 is shifted downfield 14.5 ppm relative to 4, indicating substitution a t that position, whereas the C-4 carbon experiences only a slight upfield shift. An important indicator of substitution a t the 5 position of 3 is the ca. 4.5-ppm downfield shift of the phenyl ortho carbons relative to 4. This is an effect seen in 5-substituted t r i a~o l e s ,~ presumably resulting from steric interaction between the substituents. Table I I3C Spectra of Triazolesa Compd C -4 c-5 N-Ph o-Ph m-Ph b-Ph 3 133.3 136.3 136.6 124.7 129.3 129.3 4 134.0 121.7 136.6 120.2 129.4 128.4 a Chemical shifts in parts per million relative to internal Mersi.An authentic sample of 3 was obtained by independent synthesis. Phenyl azide reacts with N-isopropylpropargylamine to yield a 60:40 mixture of 4-and 5-(N-isopropylaminornethyl)-l-phenyl-1,2,3-triazole (5 and 3). Each of the NMR signals of the major isomer appears a t lower field than the corresponding one of the minor isomer. The triazole ring protons are particularly characteristic of th'is, appearing at 6 7.85 for 5 and S 7.66 for 3. A sample of pure 3 was obtained by column chromatography and shown to be identical with the product obtained from the reaction of 1 with phenyl azide. The formation of 3 is rationalized by the addition of phenyl azide to 1 to give triazoline 6 as shown in...
The details of the previously observed lithium diethylamide isomerization of 2,3-epoxybicyclo [2.2.1] heptane to nortricyclanol have been examined. By deuterium labeling methods, it has been shown that reversible metalation occurs a t the epoxide ring and that base attack does not remove the ex0 hydrogens of the transannular bridge.The endo-5-methyl derivative 5 is transformed into the analogous tricyclic alcohol 7, whereas epoxide 6, with both transannular endo positions blocked with methyl groups, isomerizes to bicyclic ketone 9. Bornylene oxide gives camphor, epicamphor, and tricyclic alcohols 13 and 14. 2,3-Epoxybicyclo [2.2.2]octane gives ketone 19 along with minor amounts of tricyclic alcohol 20. 2,3-Epoxybicyclo[3.3.0]octane yields allylic alcohol 25 as well as lesser amounts of ketones 23 and 24. These results are used to outline the scope of the base-promoted isomerization of epoxides as a source of products derived from carbenoid insertion into transannular C-H bonds.These observations support a carbenoid mechanism for the rearrangement.
The reaction of JV-phenyldimethylketenimine (1) with peracids gives acetone, phenyl isocyanide, and a-acyloxyamide 2. Treatment of 1 with ozone also yields the first two of these products. These observations are rationalized in terms of reactive heterocyclic intermediate 3. The reaction of 1 with dimethylsulfonium ylide gives imine 5, whereas dimethyloxosulfonium ylide converts 1 to imine 6. These products are thought to be derived from 2,3-sigmatropic rearrangements of intermediates 8 and 10, formed by nucleophilic attack of the respective ylides on 1. Reaction of amide 12 with dibromotriphenylphosphorane leads to bromoketenimine 13. Ozone converts 13 to pivaloyl bromide and tert-butyl isocyanide. Reaction of 13 with MCPBA gives 15, as does its reaction with m-chlorobenzoic acid.
Die Umlagerung zahlreicher Bicyclo(2,2,l )hepten‐ und Bicyclo(2,2,2)octenoxide, die aus den entsprechenden Olefinen mit Persäure erhalten wurden, in Gegenwart von Li‐amiden liefert neben Ketonen unter Cyclisierung Nortricyclanole und deren Homoverbindungen (siehe Formelschema).
N‐Isopropyl‐allenirnin (I) reagiert mit Phenylazid (II) über (III) zum Triazol (IV).
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