ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The purely aliphatic 2,3-dipropyl-2H-azirine (1) reacts on irradiation with a mercury high-pressure lamp through a Vycor filter with methyl trifluoroacetate or acetone to form 3-oxazolines 3a, b (65%) resp. 4 (14%) (Scheme 1). 9-Azabicyclo[6.1.0]non-1(9)-ene (5) on irradiation in the presence of the dipolarophiles methyl trifluoroacetate, methyl difluoroacetate, 1,1,1-trifluoro-propanone and acetone behaves in a similar way, whereby the corresponding bicyclic 3-oxazolines 7-10 result in yields of 60-20% (Scheme 2).By analogy with the photochemical behaviour of 3-aryl-2H-azirines it is assumed that nitrile-ylides 2 resp. 6 represent intermediates. In fact irradiation of 2,3-dipropyl-2H-azirine (1, λmax 239 nm, ∊ 240) at -196° with light of wavelength 245 nm in a hydrocarbonglass gives rise to a pronounced maximum at 280 nm, for which an ∊ of ≥ 15000 can be estimated. The quantum yield for the formation of nitrile-methylide 2 is 0,8. Irradiation of the dipole 2 at -196° or warming to -150° causes the maximum at 280 nm to disappear.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19740570841
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