ISSN:
0170-2041
Keywords:
1,2-Oxazines, transformations of
;
Pyrroles
;
Molybdenum, hexacarbonyl-
;
1,4-Dicarbonyl compounds
;
Oximes
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A variety of 6-siloxy-substituted 5,6-dihydro-4H-1,2-oxazines (abbreviation: 1,2-oxazines) 1, 3 could be transformed into di- and trisubstituted pyrroles 2, 4 by means of molybdenum hexacarbonyl. The mechanism of this deoxygenating ring contraction is discussed. With two bicyclic 1,2-oxazines an acid-catalyzed fragmentation affording α-methylenecycloalkanones 7 has been observed, while other 1,2-oxazines rearrange in methanolic acid to give nitrones 9, 10. The desilylation of 6-siloxy-substituted 1,2-oxazines 1, 3 employing NEt3 · 3 HF is a very general and smooth process providing 6-hydroxy-1,2-oxazines 11, 12 or their corresponding acyclic tautomers 13, 14 in high yields. For two examples of 11 deoximations by use of formalin could be achieved with moderate efficiency giving 1,4-dicarbonyl compounds 15.
Additional Material:
6 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199019900189
