Rearrangements during Oxidations of the 9-Phosphabicyclo[6.1.0]nona-2,4,6-triene System: Formation of Phosphonin Oxides
P-Phenyl and P-tert-butyl derivatives of the title compound react with hydrogen peroxide or tert-butyl hydroperoxide at -15 °C; the C-C bond of the three-membered ring is opened, and the first observable product is the cis,cis,cis,trans-phosphonin oxide. When this oxide warms to room temperature, intramolecular cycloaddition occurs to form the trans-3a,7a-dihydro-phosphindole oxide system. The products of both processes have the stereochemistry predicted from orbital symmetry rules; their structures were established by 31P, 1H, and 13C NMR studies, as well as by conversion to known derivatives. When oxygen was used as the oxidizing agent, a different product (anti-9-phenyl-9-phosphabicydo[4.2.1]nona-2,4,7-triene 9-oxide) was formed and was useful as a precursor, on ultraviolet irradiation, of syn-9-phenyl-9-phosphatricyclo[4.2.1.02,5]nona-3,7-diene oxide. This compound was also obtained by isomerization of the anti 9-phenyl derivative with water. These oxides were reduced to the phosphines, which were characterized by NMR techniques; the syn phenyl product, however, was unstable in concentrated media and unlike the anti isomer could not be isolated. The X-ray crystallographic analysis of syn-9-phenyl-9-phosphabi-cyclo[4.2.1]nona-2,4,7-triene confirmed the stereochemical assignment and provided a structural basis for other derivatives. © 1986, American Chemical Society. All rights reserved.
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Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- General Chemistry
- 40 Engineering
- 34 Chemical sciences
- 03 Chemical Sciences